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3 Commits

Author SHA1 Message Date
Subhrodip Mohanta
a163a46e03
Merge branch 'master' into business-delegate-explanation 2021-03-22 11:46:53 +05:30
Subhrodip Mohanta
964f2c56ad
Merge branch 'master' into business-delegate-explanation 2021-03-22 11:18:16 +05:30
Ilkka Seppälä
e0f1376bd0
#590 refactor and add explanation for business delegate 2021-03-20 21:37:53 +02:00
700 changed files with 7365 additions and 26163 deletions

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@ -16,17 +16,6 @@
"content" "content"
] ]
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"profile": "http://subho.xyz",
"contributions": [
"code",
"review",
"maintenance"
]
},
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"login": "amit1307", "login": "amit1307",
"name": "amit1307", "name": "amit1307",
@ -1136,6 +1125,16 @@
"ideas" "ideas"
] ]
}, },
{
"login": "ohbus",
"name": "Subhrodip Mohanta",
"avatar_url": "https://avatars0.githubusercontent.com/u/13291222?v=4",
"profile": "http://subho.xyz",
"contributions": [
"code",
"review"
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"name": "Bethan Palmer", "name": "Bethan Palmer",
@ -1441,372 +1440,9 @@
"contributions": [ "contributions": [
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] ]
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@ -24,9 +24,6 @@
# This workflow will build a Java project with Maven # This workflow will build a Java project with Maven
# For more information see: https://help.github.com/actions/language-and-framework-guides/building-and-testing-java-with-maven # For more information see: https://help.github.com/actions/language-and-framework-guides/building-and-testing-java-with-maven
# We are using two jobs here for testing our code on the latest JDK 11 build as well as a more satble build version of 11.0.3
# You can see the full discussion here https://github.com/iluwatar/java-design-patterns/pull/1868#issue-1029459688
name: Java CI name: Java CI
on: on:
@ -36,34 +33,38 @@ on:
jobs: jobs:
# This Workflow Job will build this project and run Sonar analysis using JDK 11.0.3 build:
build-and-analyze:
name: Build and Run Sonar analysis on JDK 11.0.3
runs-on: ubuntu-20.04 runs-on: ubuntu-20.04
steps: steps:
- name: Checkout Code - name: Checkout Code
uses: actions/checkout@v2 uses: actions/checkout@master
with: with:
# Disabling shallow clone for improving relevancy of SonarQube reporting # Disabling shallow clone for improving relevancy of SonarQube reporting
fetch-depth: 0 fetch-depth: 0
- name: Set up JDK 11.0.3 - name: Set up JDK 11
uses: actions/setup-java@v2 uses: actions/setup-java@master
with: with:
java-version: 11.0.3 java-version: 11
distribution: 'zulu'
cache: 'maven'
# Cache Sonar packages which as used to run anaylysis and collect metrics
- name: Cache SonarCloud packages - name: Cache SonarCloud packages
uses: actions/cache@v2 uses: actions/cache@master
with: with:
path: ~/.sonar/cache path: ~/.sonar/cache
key: ${{ runner.os }}-sonar key: ${{ runner.os }}-sonar
restore-keys: ${{ runner.os }}-sonar restore-keys: ${{ runner.os }}-sonar
- name: Cache Maven dependencies
uses: actions/cache@master
with:
path: ~/.m2/repository
key: ${{ runner.os }}-maven-${{ hashFiles('**/pom.xml') }}
restore-keys: |
${{ runner.os }}-maven-
# Some tests need screen access # Some tests need screen access
- name: Install xvfb - name: Install xvfb
run: sudo apt-get install -y xvfb run: sudo apt-get install -y xvfb
@ -74,28 +75,3 @@ jobs:
# These two env variables are needed for sonar analysis # These two env variables are needed for sonar analysis
GITHUB_TOKEN: ${{ secrets.GITHUB_TOKEN }} GITHUB_TOKEN: ${{ secrets.GITHUB_TOKEN }}
SONAR_TOKEN: ${{ secrets.SONAR_TOKEN }} SONAR_TOKEN: ${{ secrets.SONAR_TOKEN }}
# This Workflow Job is going to build the project on the latest stable JDK 11
build:
name: Build and Test on JDK 11
runs-on: ubuntu-20.04
steps:
- name: Checkout Code
uses: actions/checkout@v2
- name: Set up JDK 11 (Latest)
uses: actions/setup-java@v2
with:
java-version: 11
distribution: 'zulu'
cache: 'maven'
# Some tests need screen access
- name: Install xvfb
run: sudo apt-get install -y xvfb
- name: Build with Maven
run: xvfb-run ./mvnw clean verify

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@ -29,27 +29,29 @@ name: Java PR Builder
on: on:
pull_request: pull_request:
branches: [ master ] branches: [ master ]
types: [ opened, reopened, synchronize ] types: [ opened, reopened, synchronize, labeled, unlabeled ]
jobs: jobs:
build: build:
name: Build JDP
runs-on: ubuntu-20.04 runs-on: ubuntu-20.04
strategy:
matrix:
java-version: [ 11.0.3, 11 ]
steps: steps:
- name: Checkout Code - name: Checkout Code
uses: actions/checkout@v2 uses: actions/checkout@master
- name: Set up JDK ${{ matrix.java-version }} - name: Set up JDK 11
uses: actions/setup-java@v2 uses: actions/setup-java@master
with: with:
java-version: ${{ matrix.java-version }} java-version: 11
distribution: 'zulu'
cache: 'maven' - name: Cache Maven Dependecies
uses: actions/cache@master
with:
path: ~/.m2/repository
key: ${{ runner.os }}-maven-${{ hashFiles('**/pom.xml') }}
restore-keys: |
${{ runner.os }}-maven-
# Some tests need screen access # Some tests need screen access
- name: Install xvfb - name: Install xvfb

1
.gitignore vendored
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@ -12,7 +12,6 @@ tmp/
local.properties local.properties
.loadpath .loadpath
.recommenders .recommenders
.DS_Store
####### Java annotation processor (APT) ######## ####### Java annotation processor (APT) ########
.factorypath .factorypath

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@ -1,18 +1,25 @@
# Licensed to the Apache Software Foundation (ASF) under one #
# or more contributor license agreements. See the NOTICE file # The MIT License
# distributed with this work for additional information # Copyright © 2014-2021 Ilkka Seppälä
# regarding copyright ownership. The ASF licenses this file #
# to you under the Apache License, Version 2.0 (the # Permission is hereby granted, free of charge, to any person obtaining a copy
# "License"); you may not use this file except in compliance # of this software and associated documentation files (the "Software"), to deal
# with the License. You may obtain a copy of the License at # in the Software without restriction, including without limitation the rights
# # to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
# http://www.apache.org/licenses/LICENSE-2.0 # copies of the Software, and to permit persons to whom the Software is
# # furnished to do so, subject to the following conditions:
# Unless required by applicable law or agreed to in writing, #
# software distributed under the License is distributed on an # The above copyright notice and this permission notice shall be included in
# "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY # all copies or substantial portions of the Software.
# KIND, either express or implied. See the License for the #
# specific language governing permissions and limitations # THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
# under the License. # IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
distributionUrl=https://repo.maven.apache.org/maven2/org/apache/maven/apache-maven/3.8.4/apache-maven-3.8.4-bin.zip # FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
wrapperUrl=https://repo.maven.apache.org/maven2/org/apache/maven/wrapper/maven-wrapper/3.1.0/maven-wrapper-3.1.0.jar # AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
# LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
# OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
# THE SOFTWARE.
#
distributionUrl=https://repo.maven.apache.org/maven2/org/apache/maven/apache-maven/3.6.3/apache-maven-3.6.3-bin.zip
wrapperUrl=https://repo.maven.apache.org/maven2/io/takari/maven-wrapper/0.5.6/maven-wrapper-0.5.6.jar

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@ -1,6 +1,6 @@
The MIT License (MIT) The MIT License (MIT)
Copyright © 2014-2021 Ilkka Seppälä Copyright (c) 2014-2021 Ilkka Seppälä
Permission is hereby granted, free of charge, to any person obtaining a copy Permission is hereby granted, free of charge, to any person obtaining a copy
of this software and associated documentation files (the "Software"), to deal of this software and associated documentation files (the "Software"), to deal
@ -19,6 +19,3 @@ AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
SOFTWARE. SOFTWARE.
Module Model-view-viewmodel is using ZK framework
ZK framework is licensed under LGPL and the license can be found at lgpl-3.0.txt

162
README.md
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@ -6,22 +6,22 @@
![Java CI](https://github.com/iluwatar/java-design-patterns/workflows/Java%20CI/badge.svg) ![Java CI](https://github.com/iluwatar/java-design-patterns/workflows/Java%20CI/badge.svg)
[![License MIT](https://img.shields.io/badge/license-MIT-blue.svg)](https://raw.githubusercontent.com/iluwatar/java-design-patterns/master/LICENSE.md) [![License MIT](https://img.shields.io/badge/license-MIT-blue.svg)](https://raw.githubusercontent.com/iluwatar/java-design-patterns/master/LICENSE.md)
[![Lines of Code](https://sonarcloud.io/api/project_badges/measure?project=iluwatar_java-design-patterns&metric=ncloc)](https://sonarcloud.io/dashboard?id=iluwatar_java-design-patterns) [![Lines of Code](https://sonarcloud.io/api/project_badges/measure?project=iluwatar_java-design-patterns&metric=ncloc)](https://sonarcloud.io/dashboard?id=iluwatar_java-design-patterns)
[![Coverage](https://sonarcloud.io/api/project_badges/measure?project=iluwatar_java-design-patterns&metric=coverage)](https://sonarcloud.io/dashboard?id=iluwatar_java-design-patterns) [![Coverage](https://sonarcloud.io/api/project_badges/measure?project=iluwatar_java-design-patterns&metric=coverage)](https://sonarcloud.io/dashboard?id=iluwatar_java-design-patterns)
[![Join the chat at https://gitter.im/iluwatar/java-design-patterns](https://badges.gitter.im/Join%20Chat.svg)](https://gitter.im/iluwatar/java-design-patterns?utm_source=badge&utm_medium=badge&utm_campaign=pr-badge&utm_content=badge) [![Join the chat at https://gitter.im/iluwatar/java-design-patterns](https://badges.gitter.im/Join%20Chat.svg)](https://gitter.im/iluwatar/java-design-patterns?utm_source=badge&utm_medium=badge&utm_campaign=pr-badge&utm_content=badge)
<!-- ALL-CONTRIBUTORS-BADGE:START - Do not remove or modify this section --> <!-- ALL-CONTRIBUTORS-BADGE:START - Do not remove or modify this section -->
[![All Contributors](https://img.shields.io/badge/all_contributors-198-orange.svg?style=flat-square)](#contributors-) [![All Contributors](https://img.shields.io/badge/all_contributors-158-orange.svg?style=flat-square)](#contributors-)
<!-- ALL-CONTRIBUTORS-BADGE:END --> <!-- ALL-CONTRIBUTORS-BADGE:END -->
<br/> <br/>
Read in different language : [**zh**](localization/zh/README.md), [**ko**](localization/ko/README.md), [**fr**](localization/fr/README.md), [**tr**](localization/tr/README.md), [**ar**](localization/ar/README.md), [**es**](localization/es/README.md), [**pt**](localization/pt/README.md), [**id**](localization/id/README.md), [**ru**](localization/ru/README.md), [**de**](localization/de/README.md), [**ja**](localization/ja/README.md) Read in different language : [![CN](/assets/flags/CN.png)**CN**](/zh/README.md), [![KR](/assets/flags/KR.png)**KR**](/ko/README.md), [![FR](/assets/flags/FR.png)**FR**](/fr/README.md), [![TR](/assets/flags/TR.png)**TR**](/tr/README.md), [![AR](/assets/flags/AR.png)**AR**](/ar/README.md)
<br/> <br/>
# Introduction # Introduction
Design patterns are the best, formalized practices a programmer can use to Design patterns are the best formalized practices a programmer can use to
solve common problems when designing an application or system. solve common problems when designing an application or system.
Design patterns can speed up the development process by providing tested, proven Design patterns can speed up the development process by providing tested, proven
@ -34,11 +34,11 @@ are familiar with the patterns.
# Getting started # Getting started
This site showcases Java Design Patterns. The solutions have been developed by This site showcases Java Design Patterns. The solutions have been developed by
experienced programmers and architects from the open-source community. The experienced programmers and architects from the open source community. The
patterns can be browsed by their high-level descriptions or by looking at their patterns can be browsed by their high level descriptions or by looking at their
source code. The source code examples are well commented and can be thought of as source code. The source code examples are well commented and can be thought as
programming tutorials on how to implement a specific pattern. We use the most programming tutorials on how to implement a specific pattern. We use the most
popular battle-proven open-source Java technologies. popular battle-proven open source Java technologies.
Before you dive into the material, you should be familiar with various Before you dive into the material, you should be familiar with various
[Software Design Principles](https://java-design-patterns.com/principles/). [Software Design Principles](https://java-design-patterns.com/principles/).
@ -49,20 +49,20 @@ patterns should only be introduced when they are needed for practical
extensibility. extensibility.
Once you are familiar with these concepts you can start drilling down into the Once you are familiar with these concepts you can start drilling down into the
[available design patterns](https://java-design-patterns.com/patterns/) by any [available design patterns](https://java-design-patterns.com/patterns/) by any
of the following approaches of the following approaches
- Search for a specific pattern by name. Can't find one? Please report a new pattern [here](https://github.com/iluwatar/java-design-patterns/issues). - Search for a specific pattern by name. Can't find one? Please report a new pattern [here](https://github.com/iluwatar/java-design-patterns/issues).
- Using tags such as `Performance`, `Gang of Four` or `Data access`. - Using tags such as `Performance`, `Gang of Four` or `Data access`.
- Using pattern categories, `Creational`, `Behavioral`, and others. - Using pattern categories, `Creational`, `Behavioral`, and others.
Hopefully, you find the object-oriented solutions presented on this site useful Hopefully you find the object oriented solutions presented on this site useful
in your architectures and have as much fun learning them as we had while developing them. in your architectures and have as much fun learning them as we had developing them.
# How to contribute # How to contribute
If you are willing to contribute to the project you will find the relevant information in If you are willing to contribute to the project you will find the relevant information in
our [developer wiki](https://github.com/iluwatar/java-design-patterns/wiki). We will help our [developer wiki](https://github.com/iluwatar/java-design-patterns/wiki). We will help
you and answer your questions in the [Gitter chatroom](https://gitter.im/iluwatar/java-design-patterns). you and answer your questions in the [Gitter chatroom](https://gitter.im/iluwatar/java-design-patterns).
# License # License
@ -77,26 +77,29 @@ This project is licensed under the terms of the MIT license.
<table> <table>
<tr> <tr>
<td align="center"><a href="https://github.com/iluwatar"><img src="https://avatars1.githubusercontent.com/u/582346?v=4?s=100" width="100px;" alt=""/><br /><sub><b>Ilkka Seppälä</b></sub></a><br /><a href="#projectManagement-iluwatar" title="Project Management">📆</a> <a href="#maintenance-iluwatar" title="Maintenance">🚧</a> <a href="#content-iluwatar" title="Content">🖋</a></td> <td align="center"><a href="https://github.com/iluwatar"><img src="https://avatars1.githubusercontent.com/u/582346?v=4?s=100" width="100px;" alt=""/><br /><sub><b>Ilkka Seppälä</b></sub></a><br /><a href="#projectManagement-iluwatar" title="Project Management">📆</a> <a href="#maintenance-iluwatar" title="Maintenance">🚧</a> <a href="#content-iluwatar" title="Content">🖋</a></td>
<td align="center"><a href="http://subho.xyz"><img src="https://avatars0.githubusercontent.com/u/13291222?v=4?s=100" width="100px;" alt=""/><br /><sub><b>Subhrodip Mohanta</b></sub></a><br /><a href="https://github.com/iluwatar/java-design-patterns/commits?author=ohbus" title="Code">💻</a> <a href="https://github.com/iluwatar/java-design-patterns/pulls?q=is%3Apr+reviewed-by%3Aohbus" title="Reviewed Pull Requests">👀</a> <a href="#maintenance-ohbus" title="Maintenance">🚧</a></td>
<td align="center"><a href="https://github.com/amit1307"><img src="https://avatars0.githubusercontent.com/u/23420222?v=4?s=100" width="100px;" alt=""/><br /><sub><b>amit1307</b></sub></a><br /><a href="https://github.com/iluwatar/java-design-patterns/commits?author=amit1307" title="Code">💻</a></td> <td align="center"><a href="https://github.com/amit1307"><img src="https://avatars0.githubusercontent.com/u/23420222?v=4?s=100" width="100px;" alt=""/><br /><sub><b>amit1307</b></sub></a><br /><a href="https://github.com/iluwatar/java-design-patterns/commits?author=amit1307" title="Code">💻</a></td>
<td align="center"><a href="https://github.com/npathai"><img src="https://avatars2.githubusercontent.com/u/1792515?v=4?s=100" width="100px;" alt=""/><br /><sub><b>Narendra Pathai</b></sub></a><br /><a href="https://github.com/iluwatar/java-design-patterns/commits?author=npathai" title="Code">💻</a> <a href="#ideas-npathai" title="Ideas, Planning, & Feedback">🤔</a> <a href="https://github.com/iluwatar/java-design-patterns/pulls?q=is%3Apr+reviewed-by%3Anpathai" title="Reviewed Pull Requests">👀</a></td> <td align="center"><a href="https://github.com/npathai"><img src="https://avatars2.githubusercontent.com/u/1792515?v=4?s=100" width="100px;" alt=""/><br /><sub><b>Narendra Pathai</b></sub></a><br /><a href="https://github.com/iluwatar/java-design-patterns/commits?author=npathai" title="Code">💻</a> <a href="#ideas-npathai" title="Ideas, Planning, & Feedback">🤔</a> <a href="https://github.com/iluwatar/java-design-patterns/pulls?q=is%3Apr+reviewed-by%3Anpathai" title="Reviewed Pull Requests">👀</a></td>
<td align="center"><a href="https://github.com/fluxw42"><img src="https://avatars1.githubusercontent.com/u/1545460?v=4?s=100" width="100px;" alt=""/><br /><sub><b>Jeroen Meulemeester</b></sub></a><br /><a href="https://github.com/iluwatar/java-design-patterns/commits?author=fluxw42" title="Code">💻</a></td> <td align="center"><a href="https://github.com/fluxw42"><img src="https://avatars1.githubusercontent.com/u/1545460?v=4?s=100" width="100px;" alt=""/><br /><sub><b>Jeroen Meulemeester</b></sub></a><br /><a href="https://github.com/iluwatar/java-design-patterns/commits?author=fluxw42" title="Code">💻</a></td>
<td align="center"><a href="http://www.joemccarthy.co.uk"><img src="https://avatars0.githubusercontent.com/u/4526195?v=4?s=100" width="100px;" alt=""/><br /><sub><b>Joseph McCarthy</b></sub></a><br /><a href="https://github.com/iluwatar/java-design-patterns/commits?author=mikulucky" title="Code">💻</a></td>
<td align="center"><a href="https://github.com/thomasoss"><img src="https://avatars1.githubusercontent.com/u/22516154?v=4?s=100" width="100px;" alt=""/><br /><sub><b>Thomas</b></sub></a><br /><a href="https://github.com/iluwatar/java-design-patterns/commits?author=thomasoss" title="Code">💻</a></td>
</tr> </tr>
<tr> <tr>
<td align="center"><a href="http://www.joemccarthy.co.uk"><img src="https://avatars0.githubusercontent.com/u/4526195?v=4?s=100" width="100px;" alt=""/><br /><sub><b>Joseph McCarthy</b></sub></a><br /><a href="https://github.com/iluwatar/java-design-patterns/commits?author=mikulucky" title="Code">💻</a></td>
<td align="center"><a href="https://github.com/thomasoss"><img src="https://avatars1.githubusercontent.com/u/22516154?v=4?s=100" width="100px;" alt=""/><br /><sub><b>Thomas</b></sub></a><br /><a href="https://github.com/iluwatar/java-design-patterns/commits?author=thomasoss" title="Code">💻</a></td>
<td align="center"><a href="https://github.com/anuragagarwal561994"><img src="https://avatars1.githubusercontent.com/u/6075379?v=4?s=100" width="100px;" alt=""/><br /><sub><b>Anurag Agarwal</b></sub></a><br /><a href="https://github.com/iluwatar/java-design-patterns/commits?author=anuragagarwal561994" title="Code">💻</a></td> <td align="center"><a href="https://github.com/anuragagarwal561994"><img src="https://avatars1.githubusercontent.com/u/6075379?v=4?s=100" width="100px;" alt=""/><br /><sub><b>Anurag Agarwal</b></sub></a><br /><a href="https://github.com/iluwatar/java-design-patterns/commits?author=anuragagarwal561994" title="Code">💻</a></td>
<td align="center"><a href="https://markusmo3.github.io"><img src="https://avatars1.githubusercontent.com/u/3317416?v=4?s=100" width="100px;" alt=""/><br /><sub><b>Markus Moser</b></sub></a><br /><a href="#design-markusmo3" title="Design">🎨</a> <a href="https://github.com/iluwatar/java-design-patterns/commits?author=markusmo3" title="Code">💻</a> <a href="#ideas-markusmo3" title="Ideas, Planning, & Feedback">🤔</a></td> <td align="center"><a href="https://markusmo3.github.io"><img src="https://avatars1.githubusercontent.com/u/3317416?v=4?s=100" width="100px;" alt=""/><br /><sub><b>Markus Moser</b></sub></a><br /><a href="#design-markusmo3" title="Design">🎨</a> <a href="https://github.com/iluwatar/java-design-patterns/commits?author=markusmo3" title="Code">💻</a> <a href="#ideas-markusmo3" title="Ideas, Planning, & Feedback">🤔</a></td>
</tr>
<tr>
<td align="center"><a href="https://twitter.com/i_sabiq"><img src="https://avatars1.githubusercontent.com/u/19510920?v=4?s=100" width="100px;" alt=""/><br /><sub><b>Sabiq Ihab</b></sub></a><br /><a href="https://github.com/iluwatar/java-design-patterns/commits?author=isabiq" title="Code">💻</a></td> <td align="center"><a href="https://twitter.com/i_sabiq"><img src="https://avatars1.githubusercontent.com/u/19510920?v=4?s=100" width="100px;" alt=""/><br /><sub><b>Sabiq Ihab</b></sub></a><br /><a href="https://github.com/iluwatar/java-design-patterns/commits?author=isabiq" title="Code">💻</a></td>
<td align="center"><a href="http://inbravo.github.io"><img src="https://avatars3.githubusercontent.com/u/5253764?v=4?s=100" width="100px;" alt=""/><br /><sub><b>Amit Dixit</b></sub></a><br /><a href="https://github.com/iluwatar/java-design-patterns/commits?author=inbravo" title="Code">💻</a></td> <td align="center"><a href="http://inbravo.github.io"><img src="https://avatars3.githubusercontent.com/u/5253764?v=4?s=100" width="100px;" alt=""/><br /><sub><b>Amit Dixit</b></sub></a><br /><a href="https://github.com/iluwatar/java-design-patterns/commits?author=inbravo" title="Code">💻</a></td>
<td align="center"><a href="https://github.com/piyushchaudhari04"><img src="https://avatars3.githubusercontent.com/u/10268029?v=4?s=100" width="100px;" alt=""/><br /><sub><b>Piyush Kailash Chaudhari</b></sub></a><br /><a href="https://github.com/iluwatar/java-design-patterns/commits?author=piyushchaudhari04" title="Code">💻</a></td> <td align="center"><a href="https://github.com/piyushchaudhari04"><img src="https://avatars3.githubusercontent.com/u/10268029?v=4?s=100" width="100px;" alt=""/><br /><sub><b>Piyush Kailash Chaudhari</b></sub></a><br /><a href="https://github.com/iluwatar/java-design-patterns/commits?author=piyushchaudhari04" title="Code">💻</a></td>
<td align="center"><a href="https://github.com/joshzambales"><img src="https://avatars1.githubusercontent.com/u/8704552?v=4?s=100" width="100px;" alt=""/><br /><sub><b>joshzambales</b></sub></a><br /><a href="https://github.com/iluwatar/java-design-patterns/commits?author=joshzambales" title="Code">💻</a></td> <td align="center"><a href="https://github.com/joshzambales"><img src="https://avatars1.githubusercontent.com/u/8704552?v=4?s=100" width="100px;" alt=""/><br /><sub><b>joshzambales</b></sub></a><br /><a href="https://github.com/iluwatar/java-design-patterns/commits?author=joshzambales" title="Code">💻</a></td>
<td align="center"><a href="https://github.com/Crossy147"><img src="https://avatars2.githubusercontent.com/u/7272996?v=4?s=100" width="100px;" alt=""/><br /><sub><b>Kamil Pietruszka</b></sub></a><br /><a href="https://github.com/iluwatar/java-design-patterns/commits?author=Crossy147" title="Code">💻</a></td>
</tr> </tr>
<tr> <tr>
<td align="center"><a href="https://github.com/Crossy147"><img src="https://avatars2.githubusercontent.com/u/7272996?v=4?s=100" width="100px;" alt=""/><br /><sub><b>Kamil Pietruszka</b></sub></a><br /><a href="https://github.com/iluwatar/java-design-patterns/commits?author=Crossy147" title="Code">💻</a></td>
<td align="center"><a href="http://cs.joensuu.fi/~zkhayda"><img src="https://avatars2.githubusercontent.com/u/660742?v=4?s=100" width="100px;" alt=""/><br /><sub><b>Zafar Khaydarov</b></sub></a><br /><a href="https://github.com/iluwatar/java-design-patterns/commits?author=zafarella" title="Code">💻</a> <a href="https://github.com/iluwatar/java-design-patterns/commits?author=zafarella" title="Documentation">📖</a></td> <td align="center"><a href="http://cs.joensuu.fi/~zkhayda"><img src="https://avatars2.githubusercontent.com/u/660742?v=4?s=100" width="100px;" alt=""/><br /><sub><b>Zafar Khaydarov</b></sub></a><br /><a href="https://github.com/iluwatar/java-design-patterns/commits?author=zafarella" title="Code">💻</a> <a href="https://github.com/iluwatar/java-design-patterns/commits?author=zafarella" title="Documentation">📖</a></td>
<td align="center"><a href="https://kemitix.github.io/"><img src="https://avatars1.githubusercontent.com/u/1147749?v=4?s=100" width="100px;" alt=""/><br /><sub><b>Paul Campbell</b></sub></a><br /><a href="https://github.com/iluwatar/java-design-patterns/commits?author=kemitix" title="Code">💻</a></td> <td align="center"><a href="https://kemitix.github.io/"><img src="https://avatars1.githubusercontent.com/u/1147749?v=4?s=100" width="100px;" alt=""/><br /><sub><b>Paul Campbell</b></sub></a><br /><a href="https://github.com/iluwatar/java-design-patterns/commits?author=kemitix" title="Code">💻</a></td>
<td align="center"><a href="https://github.com/Argyro-Sioziou"><img src="https://avatars0.githubusercontent.com/u/22822639?v=4?s=100" width="100px;" alt=""/><br /><sub><b>Argyro Sioziou</b></sub></a><br /><a href="https://github.com/iluwatar/java-design-patterns/commits?author=Argyro-Sioziou" title="Code">💻</a></td> <td align="center"><a href="https://github.com/Argyro-Sioziou"><img src="https://avatars0.githubusercontent.com/u/22822639?v=4?s=100" width="100px;" alt=""/><br /><sub><b>Argyro Sioziou</b></sub></a><br /><a href="https://github.com/iluwatar/java-design-patterns/commits?author=Argyro-Sioziou" title="Code">💻</a></td>
</tr>
<tr>
<td align="center"><a href="https://github.com/TylerMcConville"><img src="https://avatars0.githubusercontent.com/u/4946449?v=4?s=100" width="100px;" alt=""/><br /><sub><b>TylerMcConville</b></sub></a><br /><a href="https://github.com/iluwatar/java-design-patterns/commits?author=TylerMcConville" title="Code">💻</a></td> <td align="center"><a href="https://github.com/TylerMcConville"><img src="https://avatars0.githubusercontent.com/u/4946449?v=4?s=100" width="100px;" alt=""/><br /><sub><b>TylerMcConville</b></sub></a><br /><a href="https://github.com/iluwatar/java-design-patterns/commits?author=TylerMcConville" title="Code">💻</a></td>
<td align="center"><a href="https://github.com/saksham93"><img src="https://avatars1.githubusercontent.com/u/37399540?v=4?s=100" width="100px;" alt=""/><br /><sub><b>saksham93</b></sub></a><br /><a href="https://github.com/iluwatar/java-design-patterns/commits?author=saksham93" title="Code">💻</a></td> <td align="center"><a href="https://github.com/saksham93"><img src="https://avatars1.githubusercontent.com/u/37399540?v=4?s=100" width="100px;" alt=""/><br /><sub><b>saksham93</b></sub></a><br /><a href="https://github.com/iluwatar/java-design-patterns/commits?author=saksham93" title="Code">💻</a></td>
<td align="center"><a href="https://github.com/nikhilbarar"><img src="https://avatars2.githubusercontent.com/u/37332144?v=4?s=100" width="100px;" alt=""/><br /><sub><b>nikhilbarar</b></sub></a><br /><a href="https://github.com/iluwatar/java-design-patterns/commits?author=nikhilbarar" title="Code">💻</a></td> <td align="center"><a href="https://github.com/nikhilbarar"><img src="https://avatars2.githubusercontent.com/u/37332144?v=4?s=100" width="100px;" alt=""/><br /><sub><b>nikhilbarar</b></sub></a><br /><a href="https://github.com/iluwatar/java-design-patterns/commits?author=nikhilbarar" title="Code">💻</a></td>
@ -107,32 +110,38 @@ This project is licensed under the terms of the MIT license.
<td align="center"><a href="https://github.com/JuhoKang"><img src="https://avatars1.githubusercontent.com/u/4745294?v=4?s=100" width="100px;" alt=""/><br /><sub><b>Juho Kang</b></sub></a><br /><a href="https://github.com/iluwatar/java-design-patterns/commits?author=JuhoKang" title="Code">💻</a></td> <td align="center"><a href="https://github.com/JuhoKang"><img src="https://avatars1.githubusercontent.com/u/4745294?v=4?s=100" width="100px;" alt=""/><br /><sub><b>Juho Kang</b></sub></a><br /><a href="https://github.com/iluwatar/java-design-patterns/commits?author=JuhoKang" title="Code">💻</a></td>
<td align="center"><a href="https://github.com/dheeraj-mummareddy"><img src="https://avatars2.githubusercontent.com/u/7002230?v=4?s=100" width="100px;" alt=""/><br /><sub><b>Dheeraj Mummareddy</b></sub></a><br /><a href="https://github.com/iluwatar/java-design-patterns/commits?author=dheeraj-mummareddy" title="Code">💻</a></td> <td align="center"><a href="https://github.com/dheeraj-mummareddy"><img src="https://avatars2.githubusercontent.com/u/7002230?v=4?s=100" width="100px;" alt=""/><br /><sub><b>Dheeraj Mummareddy</b></sub></a><br /><a href="https://github.com/iluwatar/java-design-patterns/commits?author=dheeraj-mummareddy" title="Code">💻</a></td>
<td align="center"><a href="https://www.bernardosulzbach.com"><img src="https://avatars0.githubusercontent.com/u/8271090?v=4?s=100" width="100px;" alt=""/><br /><sub><b>Bernardo Sulzbach</b></sub></a><br /><a href="https://github.com/iluwatar/java-design-patterns/commits?author=bernardosulzbach" title="Code">💻</a></td> <td align="center"><a href="https://www.bernardosulzbach.com"><img src="https://avatars0.githubusercontent.com/u/8271090?v=4?s=100" width="100px;" alt=""/><br /><sub><b>Bernardo Sulzbach</b></sub></a><br /><a href="https://github.com/iluwatar/java-design-patterns/commits?author=bernardosulzbach" title="Code">💻</a></td>
</tr>
<tr>
<td align="center"><a href="https://github.com/4lexis"><img src="https://avatars0.githubusercontent.com/u/19871727?v=4?s=100" width="100px;" alt=""/><br /><sub><b>Aleksandar Dudukovic</b></sub></a><br /><a href="https://github.com/iluwatar/java-design-patterns/commits?author=4lexis" title="Code">💻</a></td> <td align="center"><a href="https://github.com/4lexis"><img src="https://avatars0.githubusercontent.com/u/19871727?v=4?s=100" width="100px;" alt=""/><br /><sub><b>Aleksandar Dudukovic</b></sub></a><br /><a href="https://github.com/iluwatar/java-design-patterns/commits?author=4lexis" title="Code">💻</a></td>
<td align="center"><a href="https://www.yusufaytas.com"><img src="https://avatars2.githubusercontent.com/u/1049483?v=4?s=100" width="100px;" alt=""/><br /><sub><b>Yusuf Aytaş</b></sub></a><br /><a href="https://github.com/iluwatar/java-design-patterns/commits?author=yusufaytas" title="Code">💻</a></td> <td align="center"><a href="https://www.yusufaytas.com"><img src="https://avatars2.githubusercontent.com/u/1049483?v=4?s=100" width="100px;" alt=""/><br /><sub><b>Yusuf Aytaş</b></sub></a><br /><a href="https://github.com/iluwatar/java-design-patterns/commits?author=yusufaytas" title="Code">💻</a></td>
<td align="center"><a href="http://futurehomes.hu"><img src="https://avatars2.githubusercontent.com/u/1001491?v=4?s=100" width="100px;" alt=""/><br /><sub><b>Mihály Kuprivecz</b></sub></a><br /><a href="https://github.com/iluwatar/java-design-patterns/commits?author=qpi" title="Code">💻</a></td> <td align="center"><a href="http://futurehomes.hu"><img src="https://avatars2.githubusercontent.com/u/1001491?v=4?s=100" width="100px;" alt=""/><br /><sub><b>Mihály Kuprivecz</b></sub></a><br /><a href="https://github.com/iluwatar/java-design-patterns/commits?author=qpi" title="Code">💻</a></td>
<td align="center"><a href="https://github.com/kapinuss"><img src="https://avatars0.githubusercontent.com/u/17639945?v=4?s=100" width="100px;" alt=""/><br /><sub><b>Stanislav Kapinus</b></sub></a><br /><a href="https://github.com/iluwatar/java-design-patterns/commits?author=kapinuss" title="Code">💻</a></td>
</tr> </tr>
<tr> <tr>
<td align="center"><a href="https://github.com/kapinuss"><img src="https://avatars0.githubusercontent.com/u/17639945?v=4?s=100" width="100px;" alt=""/><br /><sub><b>Stanislav Kapinus</b></sub></a><br /><a href="https://github.com/iluwatar/java-design-patterns/commits?author=kapinuss" title="Code">💻</a></td>
<td align="center"><a href="https://github.com/gvsharma"><img src="https://avatars1.githubusercontent.com/u/6648152?v=4?s=100" width="100px;" alt=""/><br /><sub><b>GVSharma</b></sub></a><br /><a href="https://github.com/iluwatar/java-design-patterns/commits?author=gvsharma" title="Code">💻</a></td> <td align="center"><a href="https://github.com/gvsharma"><img src="https://avatars1.githubusercontent.com/u/6648152?v=4?s=100" width="100px;" alt=""/><br /><sub><b>GVSharma</b></sub></a><br /><a href="https://github.com/iluwatar/java-design-patterns/commits?author=gvsharma" title="Code">💻</a></td>
<td align="center"><a href="https://github.com/SrdjanPaunovic"><img src="https://avatars1.githubusercontent.com/u/22815104?v=4?s=100" width="100px;" alt=""/><br /><sub><b>Srđan Paunović</b></sub></a><br /><a href="https://github.com/iluwatar/java-design-patterns/commits?author=SrdjanPaunovic" title="Code">💻</a></td> <td align="center"><a href="https://github.com/SrdjanPaunovic"><img src="https://avatars1.githubusercontent.com/u/22815104?v=4?s=100" width="100px;" alt=""/><br /><sub><b>Srđan Paunović</b></sub></a><br /><a href="https://github.com/iluwatar/java-design-patterns/commits?author=SrdjanPaunovic" title="Code">💻</a></td>
<td align="center"><a href="https://sideris.xyz/"><img src="https://avatars3.githubusercontent.com/u/5484694?v=4?s=100" width="100px;" alt=""/><br /><sub><b>Petros G. Sideris</b></sub></a><br /><a href="https://github.com/iluwatar/java-design-patterns/commits?author=sideris" title="Code">💻</a></td> <td align="center"><a href="https://sideris.xyz/"><img src="https://avatars3.githubusercontent.com/u/5484694?v=4?s=100" width="100px;" alt=""/><br /><sub><b>Petros G. Sideris</b></sub></a><br /><a href="https://github.com/iluwatar/java-design-patterns/commits?author=sideris" title="Code">💻</a></td>
<td align="center"><a href="https://www.linkedin.com/in/pramodgupta3/"><img src="https://avatars1.githubusercontent.com/u/2184241?v=4?s=100" width="100px;" alt=""/><br /><sub><b>Pramod Gupta</b></sub></a><br /><a href="https://github.com/iluwatar/java-design-patterns/pulls?q=is%3Apr+reviewed-by%3AIAmPramod" title="Reviewed Pull Requests">👀</a></td> <td align="center"><a href="https://www.linkedin.com/in/pramodgupta3/"><img src="https://avatars1.githubusercontent.com/u/2184241?v=4?s=100" width="100px;" alt=""/><br /><sub><b>Pramod Gupta</b></sub></a><br /><a href="https://github.com/iluwatar/java-design-patterns/pulls?q=is%3Apr+reviewed-by%3AIAmPramod" title="Reviewed Pull Requests">👀</a></td>
<td align="center"><a href="https://amarnath510.github.io/portfolio"><img src="https://avatars0.githubusercontent.com/u/4599623?v=4?s=100" width="100px;" alt=""/><br /><sub><b>Amarnath Chandana</b></sub></a><br /><a href="https://github.com/iluwatar/java-design-patterns/commits?author=Amarnath510" title="Code">💻</a></td>
<td align="center"><a href="https://github.com/Anurag870"><img src="https://avatars1.githubusercontent.com/u/6295975?v=4?s=100" width="100px;" alt=""/><br /><sub><b>Anurag870</b></sub></a><br /><a href="https://github.com/iluwatar/java-design-patterns/commits?author=Anurag870" title="Code">💻</a> <a href="https://github.com/iluwatar/java-design-patterns/commits?author=Anurag870" title="Documentation">📖</a></td>
</tr> </tr>
<tr> <tr>
<td align="center"><a href="https://amarnath510.github.io/portfolio"><img src="https://avatars0.githubusercontent.com/u/4599623?v=4?s=100" width="100px;" alt=""/><br /><sub><b>Amarnath Chandana</b></sub></a><br /><a href="https://github.com/iluwatar/java-design-patterns/commits?author=Amarnath510" title="Code">💻</a></td>
<td align="center"><a href="https://github.com/Anurag870"><img src="https://avatars1.githubusercontent.com/u/6295975?v=4?s=100" width="100px;" alt=""/><br /><sub><b>Anurag870</b></sub></a><br /><a href="https://github.com/iluwatar/java-design-patterns/commits?author=Anurag870" title="Code">💻</a> <a href="https://github.com/iluwatar/java-design-patterns/commits?author=Anurag870" title="Documentation">📖</a></td>
<td align="center"><a href="http://theerroris.me"><img src="https://avatars0.githubusercontent.com/u/1685953?v=4?s=100" width="100px;" alt=""/><br /><sub><b>Wes Gilleland</b></sub></a><br /><a href="https://github.com/iluwatar/java-design-patterns/commits?author=Deathnerd" title="Code">💻</a></td> <td align="center"><a href="http://theerroris.me"><img src="https://avatars0.githubusercontent.com/u/1685953?v=4?s=100" width="100px;" alt=""/><br /><sub><b>Wes Gilleland</b></sub></a><br /><a href="https://github.com/iluwatar/java-design-patterns/commits?author=Deathnerd" title="Code">💻</a></td>
<td align="center"><a href="https://github.com/Harshrajsinh"><img src="https://avatars2.githubusercontent.com/u/22811531?v=4?s=100" width="100px;" alt=""/><br /><sub><b>Harshraj Thakor</b></sub></a><br /><a href="https://github.com/iluwatar/java-design-patterns/commits?author=Harshrajsinh" title="Code">💻</a></td> <td align="center"><a href="https://github.com/Harshrajsinh"><img src="https://avatars2.githubusercontent.com/u/22811531?v=4?s=100" width="100px;" alt=""/><br /><sub><b>Harshraj Thakor</b></sub></a><br /><a href="https://github.com/iluwatar/java-design-patterns/commits?author=Harshrajsinh" title="Code">💻</a></td>
</tr>
<tr>
<td align="center"><a href="https://github.com/MaVdbussche"><img src="https://avatars1.githubusercontent.com/u/26136934?v=4?s=100" width="100px;" alt=""/><br /><sub><b>Martin Vandenbussche</b></sub></a><br /><a href="https://github.com/iluwatar/java-design-patterns/commits?author=MaVdbussche" title="Code">💻</a></td> <td align="center"><a href="https://github.com/MaVdbussche"><img src="https://avatars1.githubusercontent.com/u/26136934?v=4?s=100" width="100px;" alt=""/><br /><sub><b>Martin Vandenbussche</b></sub></a><br /><a href="https://github.com/iluwatar/java-design-patterns/commits?author=MaVdbussche" title="Code">💻</a></td>
<td align="center"><a href="https://alexsomai.com"><img src="https://avatars1.githubusercontent.com/u/5720977?v=4?s=100" width="100px;" alt=""/><br /><sub><b>Alexandru Somai</b></sub></a><br /><a href="https://github.com/iluwatar/java-design-patterns/commits?author=alexsomai" title="Code">💻</a></td> <td align="center"><a href="https://alexsomai.com"><img src="https://avatars1.githubusercontent.com/u/5720977?v=4?s=100" width="100px;" alt=""/><br /><sub><b>Alexandru Somai</b></sub></a><br /><a href="https://github.com/iluwatar/java-design-patterns/commits?author=alexsomai" title="Code">💻</a></td>
<td align="center"><a href="https://github.com/amogozov"><img src="https://avatars3.githubusercontent.com/u/7372215?v=4?s=100" width="100px;" alt=""/><br /><sub><b>Artur Mogozov</b></sub></a><br /><a href="https://github.com/iluwatar/java-design-patterns/commits?author=amogozov" title="Code">💻</a></td> <td align="center"><a href="https://github.com/amogozov"><img src="https://avatars3.githubusercontent.com/u/7372215?v=4?s=100" width="100px;" alt=""/><br /><sub><b>Artur Mogozov</b></sub></a><br /><a href="https://github.com/iluwatar/java-design-patterns/commits?author=amogozov" title="Code">💻</a></td>
<td align="center"><a href="https://github.com/anthonycampbell"><img src="https://avatars3.githubusercontent.com/u/10249255?v=4?s=100" width="100px;" alt=""/><br /><sub><b>anthony</b></sub></a><br /><a href="https://github.com/iluwatar/java-design-patterns/commits?author=anthonycampbell" title="Code">💻</a></td> <td align="center"><a href="https://github.com/anthonycampbell"><img src="https://avatars3.githubusercontent.com/u/10249255?v=4?s=100" width="100px;" alt=""/><br /><sub><b>anthony</b></sub></a><br /><a href="https://github.com/iluwatar/java-design-patterns/commits?author=anthonycampbell" title="Code">💻</a></td>
<td align="center"><a href="http://ccygnus.com/"><img src="https://avatars1.githubusercontent.com/u/9342724?v=4?s=100" width="100px;" alt=""/><br /><sub><b>Christian Cygnus</b></sub></a><br /><a href="https://github.com/iluwatar/java-design-patterns/commits?author=christophercolumbusdog" title="Code">💻</a></td>
</tr> </tr>
<tr> <tr>
<td align="center"><a href="http://ccygnus.com/"><img src="https://avatars1.githubusercontent.com/u/9342724?v=4?s=100" width="100px;" alt=""/><br /><sub><b>Christian Cygnus</b></sub></a><br /><a href="https://github.com/iluwatar/java-design-patterns/commits?author=christophercolumbusdog" title="Code">💻</a></td>
<td align="center"><a href="https://about.me/dzmitryh"><img src="https://avatars2.githubusercontent.com/u/5390492?v=4?s=100" width="100px;" alt=""/><br /><sub><b>Dima Gubin</b></sub></a><br /><a href="https://github.com/iluwatar/java-design-patterns/commits?author=dzmitryh" title="Code">💻</a></td> <td align="center"><a href="https://about.me/dzmitryh"><img src="https://avatars2.githubusercontent.com/u/5390492?v=4?s=100" width="100px;" alt=""/><br /><sub><b>Dima Gubin</b></sub></a><br /><a href="https://github.com/iluwatar/java-design-patterns/commits?author=dzmitryh" title="Code">💻</a></td>
<td align="center"><a href="https://github.com/jjjimenez100"><img src="https://avatars3.githubusercontent.com/u/22243493?v=4?s=100" width="100px;" alt=""/><br /><sub><b>Joshua Jimenez</b></sub></a><br /><a href="https://github.com/iluwatar/java-design-patterns/commits?author=jjjimenez100" title="Code">💻</a></td> <td align="center"><a href="https://github.com/jjjimenez100"><img src="https://avatars3.githubusercontent.com/u/22243493?v=4?s=100" width="100px;" alt=""/><br /><sub><b>Joshua Jimenez</b></sub></a><br /><a href="https://github.com/iluwatar/java-design-patterns/commits?author=jjjimenez100" title="Code">💻</a></td>
<td align="center"><a href="http://about.me/kaiwinter"><img src="https://avatars0.githubusercontent.com/u/110982?v=4?s=100" width="100px;" alt=""/><br /><sub><b>Kai Winter</b></sub></a><br /><a href="https://github.com/iluwatar/java-design-patterns/commits?author=kaiwinter" title="Code">💻</a></td> <td align="center"><a href="http://about.me/kaiwinter"><img src="https://avatars0.githubusercontent.com/u/110982?v=4?s=100" width="100px;" alt=""/><br /><sub><b>Kai Winter</b></sub></a><br /><a href="https://github.com/iluwatar/java-design-patterns/commits?author=kaiwinter" title="Code">💻</a></td>
</tr>
<tr>
<td align="center"><a href="https://github.com/lbroman"><img src="https://avatars1.githubusercontent.com/u/86007?v=4?s=100" width="100px;" alt=""/><br /><sub><b>lbroman</b></sub></a><br /><a href="https://github.com/iluwatar/java-design-patterns/commits?author=lbroman" title="Code">💻</a></td> <td align="center"><a href="https://github.com/lbroman"><img src="https://avatars1.githubusercontent.com/u/86007?v=4?s=100" width="100px;" alt=""/><br /><sub><b>lbroman</b></sub></a><br /><a href="https://github.com/iluwatar/java-design-patterns/commits?author=lbroman" title="Code">💻</a></td>
<td align="center"><a href="https://przemeknowak.com"><img src="https://avatars1.githubusercontent.com/u/3254609?v=4?s=100" width="100px;" alt=""/><br /><sub><b>Przemek</b></sub></a><br /><a href="https://github.com/iluwatar/java-design-patterns/commits?author=pnowy" title="Code">💻</a></td> <td align="center"><a href="https://przemeknowak.com"><img src="https://avatars1.githubusercontent.com/u/3254609?v=4?s=100" width="100px;" alt=""/><br /><sub><b>Przemek</b></sub></a><br /><a href="https://github.com/iluwatar/java-design-patterns/commits?author=pnowy" title="Code">💻</a></td>
<td align="center"><a href="https://github.com/prafful1"><img src="https://avatars0.githubusercontent.com/u/14350274?v=4?s=100" width="100px;" alt=""/><br /><sub><b>Prafful Agarwal</b></sub></a><br /><a href="#content-prafful1" title="Content">🖋</a></td> <td align="center"><a href="https://github.com/prafful1"><img src="https://avatars0.githubusercontent.com/u/14350274?v=4?s=100" width="100px;" alt=""/><br /><sub><b>Prafful Agarwal</b></sub></a><br /><a href="#content-prafful1" title="Content">🖋</a></td>
@ -143,32 +152,38 @@ This project is licensed under the terms of the MIT license.
<td align="center"><a href="https://github.com/valdar-hu"><img src="https://avatars3.githubusercontent.com/u/17962817?v=4?s=100" width="100px;" alt=""/><br /><sub><b>Krisztián Nagy</b></sub></a><br /><a href="https://github.com/iluwatar/java-design-patterns/commits?author=valdar-hu" title="Code">💻</a></td> <td align="center"><a href="https://github.com/valdar-hu"><img src="https://avatars3.githubusercontent.com/u/17962817?v=4?s=100" width="100px;" alt=""/><br /><sub><b>Krisztián Nagy</b></sub></a><br /><a href="https://github.com/iluwatar/java-design-patterns/commits?author=valdar-hu" title="Code">💻</a></td>
<td align="center"><a href="https://www.vanogrid.com"><img src="https://avatars0.githubusercontent.com/u/4307918?v=4?s=100" width="100px;" alt=""/><br /><sub><b>Alexander Ivanov</b></sub></a><br /><a href="https://github.com/iluwatar/java-design-patterns/commits?author=vanogrid" title="Code">💻</a></td> <td align="center"><a href="https://www.vanogrid.com"><img src="https://avatars0.githubusercontent.com/u/4307918?v=4?s=100" width="100px;" alt=""/><br /><sub><b>Alexander Ivanov</b></sub></a><br /><a href="https://github.com/iluwatar/java-design-patterns/commits?author=vanogrid" title="Code">💻</a></td>
<td align="center"><a href="https://github.com/yosfik"><img src="https://avatars3.githubusercontent.com/u/4850270?v=4?s=100" width="100px;" alt=""/><br /><sub><b>Yosfik Alqadri</b></sub></a><br /><a href="https://github.com/iluwatar/java-design-patterns/commits?author=yosfik" title="Code">💻</a></td> <td align="center"><a href="https://github.com/yosfik"><img src="https://avatars3.githubusercontent.com/u/4850270?v=4?s=100" width="100px;" alt=""/><br /><sub><b>Yosfik Alqadri</b></sub></a><br /><a href="https://github.com/iluwatar/java-design-patterns/commits?author=yosfik" title="Code">💻</a></td>
</tr>
<tr>
<td align="center"><a href="https://github.com/7agustibm"><img src="https://avatars0.githubusercontent.com/u/8149332?v=4?s=100" width="100px;" alt=""/><br /><sub><b>Agustí Becerra Milà</b></sub></a><br /><a href="https://github.com/iluwatar/java-design-patterns/commits?author=7agustibm" title="Code">💻</a></td> <td align="center"><a href="https://github.com/7agustibm"><img src="https://avatars0.githubusercontent.com/u/8149332?v=4?s=100" width="100px;" alt=""/><br /><sub><b>Agustí Becerra Milà</b></sub></a><br /><a href="https://github.com/iluwatar/java-design-patterns/commits?author=7agustibm" title="Code">💻</a></td>
<td align="center"><a href="https://github.com/Juaanma"><img src="https://avatars3.githubusercontent.com/u/7390500?v=4?s=100" width="100px;" alt=""/><br /><sub><b>Juan Manuel Suárez</b></sub></a><br /><a href="https://github.com/iluwatar/java-design-patterns/commits?author=Juaanma" title="Code">💻</a></td> <td align="center"><a href="https://github.com/Juaanma"><img src="https://avatars3.githubusercontent.com/u/7390500?v=4?s=100" width="100px;" alt=""/><br /><sub><b>Juan Manuel Suárez</b></sub></a><br /><a href="https://github.com/iluwatar/java-design-patterns/commits?author=Juaanma" title="Code">💻</a></td>
<td align="center"><a href="http://www.devsedge.net/"><img src="https://avatars0.githubusercontent.com/u/9956006?v=4?s=100" width="100px;" alt=""/><br /><sub><b>Luigi Cortese</b></sub></a><br /><a href="https://github.com/iluwatar/java-design-patterns/commits?author=LuigiCortese" title="Code">💻</a></td> <td align="center"><a href="http://www.devsedge.net/"><img src="https://avatars0.githubusercontent.com/u/9956006?v=4?s=100" width="100px;" alt=""/><br /><sub><b>Luigi Cortese</b></sub></a><br /><a href="https://github.com/iluwatar/java-design-patterns/commits?author=LuigiCortese" title="Code">💻</a></td>
<td align="center"><a href="https://github.com/Rzeposlaw"><img src="https://avatars2.githubusercontent.com/u/18425745?v=4?s=100" width="100px;" alt=""/><br /><sub><b>Katarzyna Rzepecka</b></sub></a><br /><a href="https://github.com/iluwatar/java-design-patterns/commits?author=Rzeposlaw" title="Code">💻</a></td>
</tr> </tr>
<tr> <tr>
<td align="center"><a href="https://github.com/Rzeposlaw"><img src="https://avatars2.githubusercontent.com/u/18425745?v=4?s=100" width="100px;" alt=""/><br /><sub><b>Katarzyna Rzepecka</b></sub></a><br /><a href="https://github.com/iluwatar/java-design-patterns/commits?author=Rzeposlaw" title="Code">💻</a></td>
<td align="center"><a href="http://adamski.pro"><img src="https://avatars1.githubusercontent.com/u/6537430?v=4?s=100" width="100px;" alt=""/><br /><sub><b>adamski.pro</b></sub></a><br /><a href="https://github.com/iluwatar/java-design-patterns/commits?author=akrystian" title="Code">💻</a></td> <td align="center"><a href="http://adamski.pro"><img src="https://avatars1.githubusercontent.com/u/6537430?v=4?s=100" width="100px;" alt=""/><br /><sub><b>adamski.pro</b></sub></a><br /><a href="https://github.com/iluwatar/java-design-patterns/commits?author=akrystian" title="Code">💻</a></td>
<td align="center"><a href="https://github.com/baislsl"><img src="https://avatars0.githubusercontent.com/u/17060584?v=4?s=100" width="100px;" alt=""/><br /><sub><b>Shengli Bai</b></sub></a><br /><a href="https://github.com/iluwatar/java-design-patterns/commits?author=baislsl" title="Code">💻</a></td> <td align="center"><a href="https://github.com/baislsl"><img src="https://avatars0.githubusercontent.com/u/17060584?v=4?s=100" width="100px;" alt=""/><br /><sub><b>Shengli Bai</b></sub></a><br /><a href="https://github.com/iluwatar/java-design-patterns/commits?author=baislsl" title="Code">💻</a></td>
<td align="center"><a href="https://github.com/besok"><img src="https://avatars2.githubusercontent.com/u/29834592?v=4?s=100" width="100px;" alt=""/><br /><sub><b>Boris</b></sub></a><br /><a href="https://github.com/iluwatar/java-design-patterns/commits?author=besok" title="Code">💻</a></td> <td align="center"><a href="https://github.com/besok"><img src="https://avatars2.githubusercontent.com/u/29834592?v=4?s=100" width="100px;" alt=""/><br /><sub><b>Boris</b></sub></a><br /><a href="https://github.com/iluwatar/java-design-patterns/commits?author=besok" title="Code">💻</a></td>
<td align="center"><a href="https://github.com/dmitraver"><img src="https://avatars3.githubusercontent.com/u/1798156?v=4?s=100" width="100px;" alt=""/><br /><sub><b>Dmitry Avershin</b></sub></a><br /><a href="https://github.com/iluwatar/java-design-patterns/commits?author=dmitraver" title="Code">💻</a></td> <td align="center"><a href="https://github.com/dmitraver"><img src="https://avatars3.githubusercontent.com/u/1798156?v=4?s=100" width="100px;" alt=""/><br /><sub><b>Dmitry Avershin</b></sub></a><br /><a href="https://github.com/iluwatar/java-design-patterns/commits?author=dmitraver" title="Code">💻</a></td>
<td align="center"><a href="https://github.com/fanofxiaofeng"><img src="https://avatars0.githubusercontent.com/u/3983683?v=4?s=100" width="100px;" alt=""/><br /><sub><b>靳阳</b></sub></a><br /><a href="https://github.com/iluwatar/java-design-patterns/commits?author=fanofxiaofeng" title="Code">💻</a></td>
<td align="center"><a href="https://github.com/hoangnam2261"><img src="https://avatars2.githubusercontent.com/u/31692990?v=4?s=100" width="100px;" alt=""/><br /><sub><b>hoangnam2261</b></sub></a><br /><a href="https://github.com/iluwatar/java-design-patterns/commits?author=hoangnam2261" title="Code">💻</a></td>
</tr> </tr>
<tr> <tr>
<td align="center"><a href="https://github.com/fanofxiaofeng"><img src="https://avatars0.githubusercontent.com/u/3983683?v=4?s=100" width="100px;" alt=""/><br /><sub><b>靳阳</b></sub></a><br /><a href="https://github.com/iluwatar/java-design-patterns/commits?author=fanofxiaofeng" title="Code">💻</a></td>
<td align="center"><a href="https://github.com/hoangnam2261"><img src="https://avatars2.githubusercontent.com/u/31692990?v=4?s=100" width="100px;" alt=""/><br /><sub><b>hoangnam2261</b></sub></a><br /><a href="https://github.com/iluwatar/java-design-patterns/commits?author=hoangnam2261" title="Code">💻</a></td>
<td align="center"><a href="https://github.com/jarpit96"><img src="https://avatars2.githubusercontent.com/u/10098713?v=4?s=100" width="100px;" alt=""/><br /><sub><b>Arpit Jain</b></sub></a><br /><a href="https://github.com/iluwatar/java-design-patterns/commits?author=jarpit96" title="Code">💻</a></td> <td align="center"><a href="https://github.com/jarpit96"><img src="https://avatars2.githubusercontent.com/u/10098713?v=4?s=100" width="100px;" alt=""/><br /><sub><b>Arpit Jain</b></sub></a><br /><a href="https://github.com/iluwatar/java-design-patterns/commits?author=jarpit96" title="Code">💻</a></td>
<td align="center"><a href="http://joningi.net"><img src="https://avatars2.githubusercontent.com/u/6115148?v=4?s=100" width="100px;" alt=""/><br /><sub><b>Jón Ingi Sveinbjörnsson</b></sub></a><br /><a href="https://github.com/iluwatar/java-design-patterns/commits?author=joningiwork" title="Code">💻</a></td> <td align="center"><a href="http://joningi.net"><img src="https://avatars2.githubusercontent.com/u/6115148?v=4?s=100" width="100px;" alt=""/><br /><sub><b>Jón Ingi Sveinbjörnsson</b></sub></a><br /><a href="https://github.com/iluwatar/java-design-patterns/commits?author=joningiwork" title="Code">💻</a></td>
</tr>
<tr>
<td align="center"><a href="https://github.com/kirill-vlasov"><img src="https://avatars3.githubusercontent.com/u/16112495?v=4?s=100" width="100px;" alt=""/><br /><sub><b>Kirill Vlasov</b></sub></a><br /><a href="https://github.com/iluwatar/java-design-patterns/commits?author=kirill-vlasov" title="Code">💻</a></td> <td align="center"><a href="https://github.com/kirill-vlasov"><img src="https://avatars3.githubusercontent.com/u/16112495?v=4?s=100" width="100px;" alt=""/><br /><sub><b>Kirill Vlasov</b></sub></a><br /><a href="https://github.com/iluwatar/java-design-patterns/commits?author=kirill-vlasov" title="Code">💻</a></td>
<td align="center"><a href="http://mitchell-irvin.com"><img src="https://avatars0.githubusercontent.com/u/16233245?v=4?s=100" width="100px;" alt=""/><br /><sub><b>Mitchell Irvin</b></sub></a><br /><a href="https://github.com/iluwatar/java-design-patterns/commits?author=mitchellirvin" title="Code">💻</a></td> <td align="center"><a href="http://mitchell-irvin.com"><img src="https://avatars0.githubusercontent.com/u/16233245?v=4?s=100" width="100px;" alt=""/><br /><sub><b>Mitchell Irvin</b></sub></a><br /><a href="https://github.com/iluwatar/java-design-patterns/commits?author=mitchellirvin" title="Code">💻</a></td>
<td align="center"><a href="https://ranjeet-floyd.github.io"><img src="https://avatars0.githubusercontent.com/u/1992972?v=4?s=100" width="100px;" alt=""/><br /><sub><b>Ranjeet</b></sub></a><br /><a href="https://github.com/iluwatar/java-design-patterns/commits?author=ranjeet-floyd" title="Code">💻</a></td> <td align="center"><a href="https://ranjeet-floyd.github.io"><img src="https://avatars0.githubusercontent.com/u/1992972?v=4?s=100" width="100px;" alt=""/><br /><sub><b>Ranjeet</b></sub></a><br /><a href="https://github.com/iluwatar/java-design-patterns/commits?author=ranjeet-floyd" title="Code">💻</a></td>
<td align="center"><a href="https://alwayswithme.github.io"><img src="https://avatars3.githubusercontent.com/u/3234786?v=4?s=100" width="100px;" alt=""/><br /><sub><b>PhoenixYip</b></sub></a><br /><a href="https://github.com/iluwatar/java-design-patterns/commits?author=Alwayswithme" title="Code">💻</a></td> <td align="center"><a href="https://alwayswithme.github.io"><img src="https://avatars3.githubusercontent.com/u/3234786?v=4?s=100" width="100px;" alt=""/><br /><sub><b>PhoenixYip</b></sub></a><br /><a href="https://github.com/iluwatar/java-design-patterns/commits?author=Alwayswithme" title="Code">💻</a></td>
<td align="center"><a href="https://github.com/MSaifAsif"><img src="https://avatars1.githubusercontent.com/u/6280554?v=4?s=100" width="100px;" alt=""/><br /><sub><b>M Saif Asif</b></sub></a><br /><a href="https://github.com/iluwatar/java-design-patterns/commits?author=MSaifAsif" title="Code">💻</a></td>
</tr> </tr>
<tr> <tr>
<td align="center"><a href="https://github.com/MSaifAsif"><img src="https://avatars1.githubusercontent.com/u/6280554?v=4?s=100" width="100px;" alt=""/><br /><sub><b>M Saif Asif</b></sub></a><br /><a href="https://github.com/iluwatar/java-design-patterns/commits?author=MSaifAsif" title="Code">💻</a></td>
<td align="center"><a href="https://github.com/kanwarpreet25"><img src="https://avatars0.githubusercontent.com/u/39183641?v=4?s=100" width="100px;" alt=""/><br /><sub><b>kanwarpreet25</b></sub></a><br /><a href="https://github.com/iluwatar/java-design-patterns/commits?author=kanwarpreet25" title="Code">💻</a></td> <td align="center"><a href="https://github.com/kanwarpreet25"><img src="https://avatars0.githubusercontent.com/u/39183641?v=4?s=100" width="100px;" alt=""/><br /><sub><b>kanwarpreet25</b></sub></a><br /><a href="https://github.com/iluwatar/java-design-patterns/commits?author=kanwarpreet25" title="Code">💻</a></td>
<td align="center"><a href="http://leonmak.me"><img src="https://avatars3.githubusercontent.com/u/13071508?v=4?s=100" width="100px;" alt=""/><br /><sub><b>Leon Mak</b></sub></a><br /><a href="https://github.com/iluwatar/java-design-patterns/commits?author=leonmak" title="Code">💻</a></td> <td align="center"><a href="http://leonmak.me"><img src="https://avatars3.githubusercontent.com/u/13071508?v=4?s=100" width="100px;" alt=""/><br /><sub><b>Leon Mak</b></sub></a><br /><a href="https://github.com/iluwatar/java-design-patterns/commits?author=leonmak" title="Code">💻</a></td>
<td align="center"><a href="http://www.wramdemark.se"><img src="https://avatars2.githubusercontent.com/u/7052193?v=4?s=100" width="100px;" alt=""/><br /><sub><b>Per Wramdemark</b></sub></a><br /><a href="https://github.com/iluwatar/java-design-patterns/commits?author=perwramdemark" title="Code">💻</a></td> <td align="center"><a href="http://www.wramdemark.se"><img src="https://avatars2.githubusercontent.com/u/7052193?v=4?s=100" width="100px;" alt=""/><br /><sub><b>Per Wramdemark</b></sub></a><br /><a href="https://github.com/iluwatar/java-design-patterns/commits?author=perwramdemark" title="Code">💻</a></td>
</tr>
<tr>
<td align="center"><a href="https://github.com/waisuan"><img src="https://avatars2.githubusercontent.com/u/10975700?v=4?s=100" width="100px;" alt=""/><br /><sub><b>Evan Sia Wai Suan</b></sub></a><br /><a href="https://github.com/iluwatar/java-design-patterns/commits?author=waisuan" title="Code">💻</a></td> <td align="center"><a href="https://github.com/waisuan"><img src="https://avatars2.githubusercontent.com/u/10975700?v=4?s=100" width="100px;" alt=""/><br /><sub><b>Evan Sia Wai Suan</b></sub></a><br /><a href="https://github.com/iluwatar/java-design-patterns/commits?author=waisuan" title="Code">💻</a></td>
<td align="center"><a href="https://github.com/AnaghaSasikumar"><img src="https://avatars2.githubusercontent.com/u/42939261?v=4?s=100" width="100px;" alt=""/><br /><sub><b>AnaghaSasikumar</b></sub></a><br /><a href="https://github.com/iluwatar/java-design-patterns/commits?author=AnaghaSasikumar" title="Code">💻</a></td> <td align="center"><a href="https://github.com/AnaghaSasikumar"><img src="https://avatars2.githubusercontent.com/u/42939261?v=4?s=100" width="100px;" alt=""/><br /><sub><b>AnaghaSasikumar</b></sub></a><br /><a href="https://github.com/iluwatar/java-design-patterns/commits?author=AnaghaSasikumar" title="Code">💻</a></td>
<td align="center"><a href="https://christofferh.com"><img src="https://avatars1.githubusercontent.com/u/767643?v=4?s=100" width="100px;" alt=""/><br /><sub><b>Christoffer Hamberg</b></sub></a><br /><a href="https://github.com/iluwatar/java-design-patterns/commits?author=christofferh" title="Code">💻</a></td> <td align="center"><a href="https://christofferh.com"><img src="https://avatars1.githubusercontent.com/u/767643?v=4?s=100" width="100px;" alt=""/><br /><sub><b>Christoffer Hamberg</b></sub></a><br /><a href="https://github.com/iluwatar/java-design-patterns/commits?author=christofferh" title="Code">💻</a></td>
@ -179,32 +194,38 @@ This project is licensed under the terms of the MIT license.
<td align="center"><a href="https://github.com/leogtzr"><img src="https://avatars0.githubusercontent.com/u/1211969?v=4?s=100" width="100px;" alt=""/><br /><sub><b>Leo Gutiérrez Ramírez</b></sub></a><br /><a href="https://github.com/iluwatar/java-design-patterns/commits?author=leogtzr" title="Code">💻</a></td> <td align="center"><a href="https://github.com/leogtzr"><img src="https://avatars0.githubusercontent.com/u/1211969?v=4?s=100" width="100px;" alt=""/><br /><sub><b>Leo Gutiérrez Ramírez</b></sub></a><br /><a href="https://github.com/iluwatar/java-design-patterns/commits?author=leogtzr" title="Code">💻</a></td>
<td align="center"><a href="https://github.com/npczwh"><img src="https://avatars0.githubusercontent.com/u/14066422?v=4?s=100" width="100px;" alt=""/><br /><sub><b>Zhang WH</b></sub></a><br /><a href="https://github.com/iluwatar/java-design-patterns/commits?author=npczwh" title="Code">💻</a></td> <td align="center"><a href="https://github.com/npczwh"><img src="https://avatars0.githubusercontent.com/u/14066422?v=4?s=100" width="100px;" alt=""/><br /><sub><b>Zhang WH</b></sub></a><br /><a href="https://github.com/iluwatar/java-design-patterns/commits?author=npczwh" title="Code">💻</a></td>
<td align="center"><a href="https://github.com/oconnelc"><img src="https://avatars0.githubusercontent.com/u/1112973?v=4?s=100" width="100px;" alt=""/><br /><sub><b>Christopher O'Connell</b></sub></a><br /><a href="https://github.com/iluwatar/java-design-patterns/commits?author=oconnelc" title="Code">💻</a></td> <td align="center"><a href="https://github.com/oconnelc"><img src="https://avatars0.githubusercontent.com/u/1112973?v=4?s=100" width="100px;" alt=""/><br /><sub><b>Christopher O'Connell</b></sub></a><br /><a href="https://github.com/iluwatar/java-design-patterns/commits?author=oconnelc" title="Code">💻</a></td>
</tr>
<tr>
<td align="center"><a href="https://github.com/giorgosmav21"><img src="https://avatars2.githubusercontent.com/u/22855493?v=4?s=100" width="100px;" alt=""/><br /><sub><b>George Mavroeidis</b></sub></a><br /><a href="https://github.com/iluwatar/java-design-patterns/commits?author=giorgosmav21" title="Code">💻</a></td> <td align="center"><a href="https://github.com/giorgosmav21"><img src="https://avatars2.githubusercontent.com/u/22855493?v=4?s=100" width="100px;" alt=""/><br /><sub><b>George Mavroeidis</b></sub></a><br /><a href="https://github.com/iluwatar/java-design-patterns/commits?author=giorgosmav21" title="Code">💻</a></td>
<td align="center"><a href="https://github.com/hbothra15"><img src="https://avatars1.githubusercontent.com/u/7418012?v=4?s=100" width="100px;" alt=""/><br /><sub><b>Hemant Bothra</b></sub></a><br /><a href="https://github.com/iluwatar/java-design-patterns/commits?author=hbothra15" title="Code">💻</a> <a href="#design-hbothra15" title="Design">🎨</a></td> <td align="center"><a href="https://github.com/hbothra15"><img src="https://avatars1.githubusercontent.com/u/7418012?v=4?s=100" width="100px;" alt=""/><br /><sub><b>Hemant Bothra</b></sub></a><br /><a href="https://github.com/iluwatar/java-design-patterns/commits?author=hbothra15" title="Code">💻</a> <a href="#design-hbothra15" title="Design">🎨</a></td>
<td align="center"><a href="https://www.kevinpeters.net/about/"><img src="https://avatars1.githubusercontent.com/u/12736734?v=4?s=100" width="100px;" alt=""/><br /><sub><b>Kevin Peters</b></sub></a><br /><a href="https://github.com/iluwatar/java-design-patterns/commits?author=igeligel" title="Code">💻</a></td> <td align="center"><a href="https://www.kevinpeters.net/about/"><img src="https://avatars1.githubusercontent.com/u/12736734?v=4?s=100" width="100px;" alt=""/><br /><sub><b>Kevin Peters</b></sub></a><br /><a href="https://github.com/iluwatar/java-design-patterns/commits?author=igeligel" title="Code">💻</a></td>
<td align="center"><a href="https://llorllale.github.io/"><img src="https://avatars1.githubusercontent.com/u/2019896?v=4?s=100" width="100px;" alt=""/><br /><sub><b>George Aristy</b></sub></a><br /><a href="https://github.com/iluwatar/java-design-patterns/commits?author=llorllale" title="Code">💻</a></td>
</tr> </tr>
<tr> <tr>
<td align="center"><a href="https://llorllale.github.io/"><img src="https://avatars1.githubusercontent.com/u/2019896?v=4?s=100" width="100px;" alt=""/><br /><sub><b>George Aristy</b></sub></a><br /><a href="https://github.com/iluwatar/java-design-patterns/commits?author=llorllale" title="Code">💻</a></td>
<td align="center"><a href="https://github.com/mookkiah"><img src="https://avatars1.githubusercontent.com/u/8975264?v=4?s=100" width="100px;" alt=""/><br /><sub><b>Mahendran Mookkiah</b></sub></a><br /><a href="https://github.com/iluwatar/java-design-patterns/commits?author=mookkiah" title="Code">💻</a></td> <td align="center"><a href="https://github.com/mookkiah"><img src="https://avatars1.githubusercontent.com/u/8975264?v=4?s=100" width="100px;" alt=""/><br /><sub><b>Mahendran Mookkiah</b></sub></a><br /><a href="https://github.com/iluwatar/java-design-patterns/commits?author=mookkiah" title="Code">💻</a></td>
<td align="center"><a href="https://github.com/Azureyjt"><img src="https://avatars2.githubusercontent.com/u/18476317?v=4?s=100" width="100px;" alt=""/><br /><sub><b>Azureyjt</b></sub></a><br /><a href="https://github.com/iluwatar/java-design-patterns/commits?author=Azureyjt" title="Code">💻</a></td> <td align="center"><a href="https://github.com/Azureyjt"><img src="https://avatars2.githubusercontent.com/u/18476317?v=4?s=100" width="100px;" alt=""/><br /><sub><b>Azureyjt</b></sub></a><br /><a href="https://github.com/iluwatar/java-design-patterns/commits?author=Azureyjt" title="Code">💻</a></td>
<td align="center"><a href="https://github.com/vehpsr"><img src="https://avatars2.githubusercontent.com/u/3133265?v=4?s=100" width="100px;" alt=""/><br /><sub><b>gans</b></sub></a><br /><a href="https://github.com/iluwatar/java-design-patterns/commits?author=vehpsr" title="Code">💻</a></td> <td align="center"><a href="https://github.com/vehpsr"><img src="https://avatars2.githubusercontent.com/u/3133265?v=4?s=100" width="100px;" alt=""/><br /><sub><b>gans</b></sub></a><br /><a href="https://github.com/iluwatar/java-design-patterns/commits?author=vehpsr" title="Code">💻</a></td>
<td align="center"><a href="https://github.com/ThatGuyWithTheHat"><img src="https://avatars0.githubusercontent.com/u/24470582?v=4?s=100" width="100px;" alt=""/><br /><sub><b>Matt</b></sub></a><br /><a href="#content-ThatGuyWithTheHat" title="Content">🖋</a></td> <td align="center"><a href="https://github.com/ThatGuyWithTheHat"><img src="https://avatars0.githubusercontent.com/u/24470582?v=4?s=100" width="100px;" alt=""/><br /><sub><b>Matt</b></sub></a><br /><a href="#content-ThatGuyWithTheHat" title="Content">🖋</a></td>
<td align="center"><a href="https://www.linkedin.com/in/gopinathlangote/"><img src="https://avatars2.githubusercontent.com/u/10210778?v=4?s=100" width="100px;" alt=""/><br /><sub><b>Gopinath Langote</b></sub></a><br /><a href="https://github.com/iluwatar/java-design-patterns/commits?author=gopinath-langote" title="Code">💻</a></td>
<td align="center"><a href="https://github.com/hoswey"><img src="https://avatars3.githubusercontent.com/u/3689445?v=4?s=100" width="100px;" alt=""/><br /><sub><b>Hoswey</b></sub></a><br /><a href="https://github.com/iluwatar/java-design-patterns/commits?author=hoswey" title="Code">💻</a></td>
</tr> </tr>
<tr> <tr>
<td align="center"><a href="https://www.linkedin.com/in/gopinathlangote/"><img src="https://avatars2.githubusercontent.com/u/10210778?v=4?s=100" width="100px;" alt=""/><br /><sub><b>Gopinath Langote</b></sub></a><br /><a href="https://github.com/iluwatar/java-design-patterns/commits?author=gopinath-langote" title="Code">💻</a></td>
<td align="center"><a href="https://github.com/hoswey"><img src="https://avatars3.githubusercontent.com/u/3689445?v=4?s=100" width="100px;" alt=""/><br /><sub><b>Hoswey</b></sub></a><br /><a href="https://github.com/iluwatar/java-design-patterns/commits?author=hoswey" title="Code">💻</a></td>
<td align="center"><a href="https://github.com/amit2103"><img src="https://avatars3.githubusercontent.com/u/7566692?v=4?s=100" width="100px;" alt=""/><br /><sub><b>Amit Pandey</b></sub></a><br /><a href="https://github.com/iluwatar/java-design-patterns/commits?author=amit2103" title="Code">💻</a></td> <td align="center"><a href="https://github.com/amit2103"><img src="https://avatars3.githubusercontent.com/u/7566692?v=4?s=100" width="100px;" alt=""/><br /><sub><b>Amit Pandey</b></sub></a><br /><a href="https://github.com/iluwatar/java-design-patterns/commits?author=amit2103" title="Code">💻</a></td>
<td align="center"><a href="https://github.com/gwildor28"><img src="https://avatars0.githubusercontent.com/u/16000365?v=4?s=100" width="100px;" alt=""/><br /><sub><b>gwildor28</b></sub></a><br /><a href="#content-gwildor28" title="Content">🖋</a></td> <td align="center"><a href="https://github.com/gwildor28"><img src="https://avatars0.githubusercontent.com/u/16000365?v=4?s=100" width="100px;" alt=""/><br /><sub><b>gwildor28</b></sub></a><br /><a href="#content-gwildor28" title="Content">🖋</a></td>
</tr>
<tr>
<td align="center"><a href="https://t.me/paul_docker"><img src="https://avatars1.githubusercontent.com/u/2404785?v=4?s=100" width="100px;" alt=""/><br /><sub><b>田浩</b></sub></a><br /><a href="#content-llitfkitfk" title="Content">🖋</a></td> <td align="center"><a href="https://t.me/paul_docker"><img src="https://avatars1.githubusercontent.com/u/2404785?v=4?s=100" width="100px;" alt=""/><br /><sub><b>田浩</b></sub></a><br /><a href="#content-llitfkitfk" title="Content">🖋</a></td>
<td align="center"><a href="https://twitter.com/StPitsios"><img src="https://avatars1.githubusercontent.com/u/6773603?v=4?s=100" width="100px;" alt=""/><br /><sub><b>Stamatis Pitsios</b></sub></a><br /><a href="https://github.com/iluwatar/java-design-patterns/commits?author=pitsios-s" title="Code">💻</a></td> <td align="center"><a href="https://twitter.com/StPitsios"><img src="https://avatars1.githubusercontent.com/u/6773603?v=4?s=100" width="100px;" alt=""/><br /><sub><b>Stamatis Pitsios</b></sub></a><br /><a href="https://github.com/iluwatar/java-design-patterns/commits?author=pitsios-s" title="Code">💻</a></td>
<td align="center"><a href="https://github.com/qza"><img src="https://avatars3.githubusercontent.com/u/233149?v=4?s=100" width="100px;" alt=""/><br /><sub><b>qza</b></sub></a><br /><a href="https://github.com/iluwatar/java-design-patterns/commits?author=qza" title="Code">💻</a></td> <td align="center"><a href="https://github.com/qza"><img src="https://avatars3.githubusercontent.com/u/233149?v=4?s=100" width="100px;" alt=""/><br /><sub><b>qza</b></sub></a><br /><a href="https://github.com/iluwatar/java-design-patterns/commits?author=qza" title="Code">💻</a></td>
<td align="center"><a href="http://tschis.github.io"><img src="https://avatars1.githubusercontent.com/u/20662669?v=4?s=100" width="100px;" alt=""/><br /><sub><b>Rodolfo Forte</b></sub></a><br /><a href="#content-Tschis" title="Content">🖋</a></td> <td align="center"><a href="http://tschis.github.io"><img src="https://avatars1.githubusercontent.com/u/20662669?v=4?s=100" width="100px;" alt=""/><br /><sub><b>Rodolfo Forte</b></sub></a><br /><a href="#content-Tschis" title="Content">🖋</a></td>
<td align="center"><a href="https://github.com/ankurkaushal"><img src="https://avatars2.githubusercontent.com/u/2236616?v=4?s=100" width="100px;" alt=""/><br /><sub><b>Ankur Kaushal</b></sub></a><br /><a href="https://github.com/iluwatar/java-design-patterns/commits?author=ankurkaushal" title="Code">💻</a></td>
</tr> </tr>
<tr> <tr>
<td align="center"><a href="https://github.com/ankurkaushal"><img src="https://avatars2.githubusercontent.com/u/2236616?v=4?s=100" width="100px;" alt=""/><br /><sub><b>Ankur Kaushal</b></sub></a><br /><a href="https://github.com/iluwatar/java-design-patterns/commits?author=ankurkaushal" title="Code">💻</a></td>
<td align="center"><a href="https://www.linkedin.com/in/ovidijus-okinskas/"><img src="https://avatars0.githubusercontent.com/u/20372387?v=4?s=100" width="100px;" alt=""/><br /><sub><b>Ovidijus Okinskas</b></sub></a><br /><a href="https://github.com/iluwatar/java-design-patterns/commits?author=okinskas" title="Code">💻</a></td> <td align="center"><a href="https://www.linkedin.com/in/ovidijus-okinskas/"><img src="https://avatars0.githubusercontent.com/u/20372387?v=4?s=100" width="100px;" alt=""/><br /><sub><b>Ovidijus Okinskas</b></sub></a><br /><a href="https://github.com/iluwatar/java-design-patterns/commits?author=okinskas" title="Code">💻</a></td>
<td align="center"><a href="https://github.com/robertt240"><img src="https://avatars1.githubusercontent.com/u/9137432?v=4?s=100" width="100px;" alt=""/><br /><sub><b>Robert Kasperczyk</b></sub></a><br /><a href="https://github.com/iluwatar/java-design-patterns/commits?author=robertt240" title="Code">💻</a></td> <td align="center"><a href="https://github.com/robertt240"><img src="https://avatars1.githubusercontent.com/u/9137432?v=4?s=100" width="100px;" alt=""/><br /><sub><b>Robert Kasperczyk</b></sub></a><br /><a href="https://github.com/iluwatar/java-design-patterns/commits?author=robertt240" title="Code">💻</a></td>
<td align="center"><a href="https://github.com/trautonen"><img src="https://avatars3.githubusercontent.com/u/1641063?v=4?s=100" width="100px;" alt=""/><br /><sub><b>Tapio Rautonen</b></sub></a><br /><a href="https://github.com/iluwatar/java-design-patterns/commits?author=trautonen" title="Code">💻</a></td> <td align="center"><a href="https://github.com/trautonen"><img src="https://avatars3.githubusercontent.com/u/1641063?v=4?s=100" width="100px;" alt=""/><br /><sub><b>Tapio Rautonen</b></sub></a><br /><a href="https://github.com/iluwatar/java-design-patterns/commits?author=trautonen" title="Code">💻</a></td>
</tr>
<tr>
<td align="center"><a href="http://vk.com/yuri.orlov"><img src="https://avatars0.githubusercontent.com/u/1595733?v=4?s=100" width="100px;" alt=""/><br /><sub><b>Yuri Orlov</b></sub></a><br /><a href="https://github.com/iluwatar/java-design-patterns/commits?author=yorlov" title="Code">💻</a></td> <td align="center"><a href="http://vk.com/yuri.orlov"><img src="https://avatars0.githubusercontent.com/u/1595733?v=4?s=100" width="100px;" alt=""/><br /><sub><b>Yuri Orlov</b></sub></a><br /><a href="https://github.com/iluwatar/java-design-patterns/commits?author=yorlov" title="Code">💻</a></td>
<td align="center"><a href="https://www.linkedin.com/in/varunu28/"><img src="https://avatars0.githubusercontent.com/u/7676016?v=4?s=100" width="100px;" alt=""/><br /><sub><b>Varun Upadhyay</b></sub></a><br /><a href="https://github.com/iluwatar/java-design-patterns/commits?author=varunu28" title="Code">💻</a></td> <td align="center"><a href="https://www.linkedin.com/in/varunu28/"><img src="https://avatars0.githubusercontent.com/u/7676016?v=4?s=100" width="100px;" alt=""/><br /><sub><b>Varun Upadhyay</b></sub></a><br /><a href="https://github.com/iluwatar/java-design-patterns/commits?author=varunu28" title="Code">💻</a></td>
<td align="center"><a href="https://github.com/PalAditya"><img src="https://avatars2.githubusercontent.com/u/25523604?v=4?s=100" width="100px;" alt=""/><br /><sub><b>Aditya Pal</b></sub></a><br /><a href="https://github.com/iluwatar/java-design-patterns/commits?author=PalAditya" title="Code">💻</a></td> <td align="center"><a href="https://github.com/PalAditya"><img src="https://avatars2.githubusercontent.com/u/25523604?v=4?s=100" width="100px;" alt=""/><br /><sub><b>Aditya Pal</b></sub></a><br /><a href="https://github.com/iluwatar/java-design-patterns/commits?author=PalAditya" title="Code">💻</a></td>
@ -215,41 +236,50 @@ This project is licensed under the terms of the MIT license.
<td align="center"><a href="https://github.com/d4gg4d"><img src="https://avatars2.githubusercontent.com/u/99457?v=4?s=100" width="100px;" alt=""/><br /><sub><b>Sami Airaksinen</b></sub></a><br /><a href="https://github.com/iluwatar/java-design-patterns/commits?author=d4gg4d" title="Code">💻</a></td> <td align="center"><a href="https://github.com/d4gg4d"><img src="https://avatars2.githubusercontent.com/u/99457?v=4?s=100" width="100px;" alt=""/><br /><sub><b>Sami Airaksinen</b></sub></a><br /><a href="https://github.com/iluwatar/java-design-patterns/commits?author=d4gg4d" title="Code">💻</a></td>
<td align="center"><a href="https://github.com/vertti"><img src="https://avatars0.githubusercontent.com/u/557751?v=4?s=100" width="100px;" alt=""/><br /><sub><b>Janne Sinivirta</b></sub></a><br /><a href="https://github.com/iluwatar/java-design-patterns/commits?author=vertti" title="Code">💻</a></td> <td align="center"><a href="https://github.com/vertti"><img src="https://avatars0.githubusercontent.com/u/557751?v=4?s=100" width="100px;" alt=""/><br /><sub><b>Janne Sinivirta</b></sub></a><br /><a href="https://github.com/iluwatar/java-design-patterns/commits?author=vertti" title="Code">💻</a></td>
<td align="center"><a href="https://github.com/Bobo1239"><img src="https://avatars1.githubusercontent.com/u/2302947?v=4?s=100" width="100px;" alt=""/><br /><sub><b>Boris-Chengbiao Zhou</b></sub></a><br /><a href="#content-Bobo1239" title="Content">🖋</a></td> <td align="center"><a href="https://github.com/Bobo1239"><img src="https://avatars1.githubusercontent.com/u/2302947?v=4?s=100" width="100px;" alt=""/><br /><sub><b>Boris-Chengbiao Zhou</b></sub></a><br /><a href="#content-Bobo1239" title="Content">🖋</a></td>
</tr>
<tr>
<td align="center"><a href="https://jahhein.github.io"><img src="https://avatars2.githubusercontent.com/u/10779515?v=4?s=100" width="100px;" alt=""/><br /><sub><b>Jacob Hein</b></sub></a><br /><a href="#content-Jahhein" title="Content">🖋</a></td> <td align="center"><a href="https://jahhein.github.io"><img src="https://avatars2.githubusercontent.com/u/10779515?v=4?s=100" width="100px;" alt=""/><br /><sub><b>Jacob Hein</b></sub></a><br /><a href="#content-Jahhein" title="Content">🖋</a></td>
<td align="center"><a href="https://github.com/iamrichardjones"><img src="https://avatars3.githubusercontent.com/u/14842151?v=4?s=100" width="100px;" alt=""/><br /><sub><b>Richard Jones</b></sub></a><br /><a href="#content-iamrichardjones" title="Content">🖋</a></td> <td align="center"><a href="https://github.com/iamrichardjones"><img src="https://avatars3.githubusercontent.com/u/14842151?v=4?s=100" width="100px;" alt=""/><br /><sub><b>Richard Jones</b></sub></a><br /><a href="#content-iamrichardjones" title="Content">🖋</a></td>
<td align="center"><a href="https://rachelcarmena.github.io"><img src="https://avatars0.githubusercontent.com/u/22792183?v=4?s=100" width="100px;" alt=""/><br /><sub><b>Rachel M. Carmena</b></sub></a><br /><a href="#content-rachelcarmena" title="Content">🖋</a></td> <td align="center"><a href="https://rachelcarmena.github.io"><img src="https://avatars0.githubusercontent.com/u/22792183?v=4?s=100" width="100px;" alt=""/><br /><sub><b>Rachel M. Carmena</b></sub></a><br /><a href="#content-rachelcarmena" title="Content">🖋</a></td>
<td align="center"><a href="https://zd-zero.github.io"><img src="https://avatars0.githubusercontent.com/u/21978370?v=4?s=100" width="100px;" alt=""/><br /><sub><b>Zaerald Denze Lungos</b></sub></a><br /><a href="#content-zd-zero" title="Content">🖋</a></td>
</tr> </tr>
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<td align="center"><a href="https://zd-zero.github.io"><img src="https://avatars0.githubusercontent.com/u/21978370?v=4?s=100" width="100px;" alt=""/><br /><sub><b>Zaerald Denze Lungos</b></sub></a><br /><a href="#content-zd-zero" title="Content">🖋</a></td>
<td align="center"><a href="https://webpro.nl"><img src="https://avatars1.githubusercontent.com/u/456426?v=4?s=100" width="100px;" alt=""/><br /><sub><b>Lars Kappert</b></sub></a><br /><a href="#content-webpro" title="Content">🖋</a></td> <td align="center"><a href="https://webpro.nl"><img src="https://avatars1.githubusercontent.com/u/456426?v=4?s=100" width="100px;" alt=""/><br /><sub><b>Lars Kappert</b></sub></a><br /><a href="#content-webpro" title="Content">🖋</a></td>
<td align="center"><a href="https://xiaod.info"><img src="https://avatars2.githubusercontent.com/u/21277644?v=4?s=100" width="100px;" alt=""/><br /><sub><b>Mike Liu</b></sub></a><br /><a href="#translation-xiaod-dev" title="Translation">🌍</a></td> <td align="center"><a href="https://xiaod.info"><img src="https://avatars2.githubusercontent.com/u/21277644?v=4?s=100" width="100px;" alt=""/><br /><sub><b>Mike Liu</b></sub></a><br /><a href="#translation-xiaod-dev" title="Translation">🌍</a></td>
<td align="center"><a href="https://github.com/charlesfinley"><img src="https://avatars1.githubusercontent.com/u/6307904?v=4?s=100" width="100px;" alt=""/><br /><sub><b>Matt Dolan</b></sub></a><br /><a href="https://github.com/iluwatar/java-design-patterns/commits?author=charlesfinley" title="Code">💻</a> <a href="https://github.com/iluwatar/java-design-patterns/pulls?q=is%3Apr+reviewed-by%3Acharlesfinley" title="Reviewed Pull Requests">👀</a></td> <td align="center"><a href="https://github.com/charlesfinley"><img src="https://avatars1.githubusercontent.com/u/6307904?v=4?s=100" width="100px;" alt=""/><br /><sub><b>Matt Dolan</b></sub></a><br /><a href="https://github.com/iluwatar/java-design-patterns/commits?author=charlesfinley" title="Code">💻</a> <a href="https://github.com/iluwatar/java-design-patterns/pulls?q=is%3Apr+reviewed-by%3Acharlesfinley" title="Reviewed Pull Requests">👀</a></td>
<td align="center"><a href="https://github.com/MananS77"><img src="https://avatars3.githubusercontent.com/u/21033516?v=4?s=100" width="100px;" alt=""/><br /><sub><b>Manan</b></sub></a><br /><a href="https://github.com/iluwatar/java-design-patterns/pulls?q=is%3Apr+reviewed-by%3AMananS77" title="Reviewed Pull Requests">👀</a></td> <td align="center"><a href="https://github.com/MananS77"><img src="https://avatars3.githubusercontent.com/u/21033516?v=4?s=100" width="100px;" alt=""/><br /><sub><b>Manan</b></sub></a><br /><a href="https://github.com/iluwatar/java-design-patterns/pulls?q=is%3Apr+reviewed-by%3AMananS77" title="Reviewed Pull Requests">👀</a></td>
<td align="center"><a href="https://github.com/nishant"><img src="https://avatars2.githubusercontent.com/u/15331971?v=4?s=100" width="100px;" alt=""/><br /><sub><b>Nishant Arora</b></sub></a><br /><a href="https://github.com/iluwatar/java-design-patterns/commits?author=nishant" title="Code">💻</a></td>
<td align="center"><a href="https://github.com/raja-peeyush-kumar-singh"><img src="https://avatars0.githubusercontent.com/u/5496024?v=4?s=100" width="100px;" alt=""/><br /><sub><b>Peeyush</b></sub></a><br /><a href="https://github.com/iluwatar/java-design-patterns/commits?author=raja-peeyush-kumar-singh" title="Code">💻</a></td>
</tr> </tr>
<tr> <tr>
<td align="center"><a href="https://github.com/nishant"><img src="https://avatars2.githubusercontent.com/u/15331971?v=4?s=100" width="100px;" alt=""/><br /><sub><b>Nishant Arora</b></sub></a><br /><a href="https://github.com/iluwatar/java-design-patterns/commits?author=nishant" title="Code">💻</a></td>
<td align="center"><a href="https://github.com/raja-peeyush-kumar-singh"><img src="https://avatars0.githubusercontent.com/u/5496024?v=4?s=100" width="100px;" alt=""/><br /><sub><b>Peeyush</b></sub></a><br /><a href="https://github.com/iluwatar/java-design-patterns/commits?author=raja-peeyush-kumar-singh" title="Code">💻</a></td>
<td align="center"><a href="https://github.com/ravening"><img src="https://avatars1.githubusercontent.com/u/10645273?v=4?s=100" width="100px;" alt=""/><br /><sub><b>Rakesh</b></sub></a><br /><a href="https://github.com/iluwatar/java-design-patterns/commits?author=ravening" title="Code">💻</a> <a href="https://github.com/iluwatar/java-design-patterns/pulls?q=is%3Apr+reviewed-by%3Aravening" title="Reviewed Pull Requests">👀</a></td> <td align="center"><a href="https://github.com/ravening"><img src="https://avatars1.githubusercontent.com/u/10645273?v=4?s=100" width="100px;" alt=""/><br /><sub><b>Rakesh</b></sub></a><br /><a href="https://github.com/iluwatar/java-design-patterns/commits?author=ravening" title="Code">💻</a> <a href="https://github.com/iluwatar/java-design-patterns/pulls?q=is%3Apr+reviewed-by%3Aravening" title="Reviewed Pull Requests">👀</a></td>
<td align="center"><a href="https://github.com/vINCENT8888801"><img src="https://avatars0.githubusercontent.com/u/8037883?v=4?s=100" width="100px;" alt=""/><br /><sub><b>Wei Seng</b></sub></a><br /><a href="https://github.com/iluwatar/java-design-patterns/commits?author=vINCENT8888801" title="Code">💻</a></td> <td align="center"><a href="https://github.com/vINCENT8888801"><img src="https://avatars0.githubusercontent.com/u/8037883?v=4?s=100" width="100px;" alt=""/><br /><sub><b>Wei Seng</b></sub></a><br /><a href="https://github.com/iluwatar/java-design-patterns/commits?author=vINCENT8888801" title="Code">💻</a></td>
</tr>
<tr>
<td align="center"><a href="https://www.linkedin.com/in/ashish-trivedi-218379135/"><img src="https://avatars3.githubusercontent.com/u/23194128?v=4?s=100" width="100px;" alt=""/><br /><sub><b>Ashish Trivedi</b></sub></a><br /><a href="https://github.com/iluwatar/java-design-patterns/commits?author=ashishtrivedi16" title="Code">💻</a></td> <td align="center"><a href="https://www.linkedin.com/in/ashish-trivedi-218379135/"><img src="https://avatars3.githubusercontent.com/u/23194128?v=4?s=100" width="100px;" alt=""/><br /><sub><b>Ashish Trivedi</b></sub></a><br /><a href="https://github.com/iluwatar/java-design-patterns/commits?author=ashishtrivedi16" title="Code">💻</a></td>
<td align="center"><a href="https://rayyounghong.com"><img src="https://avatars1.githubusercontent.com/u/41055099?v=4?s=100" width="100px;" alt=""/><br /><sub><b>洪月阳</b></sub></a><br /><a href="https://github.com/iluwatar/java-design-patterns/commits?author=RayYH" title="Code">💻</a></td> <td align="center"><a href="https://rayyounghong.com"><img src="https://avatars1.githubusercontent.com/u/41055099?v=4?s=100" width="100px;" alt=""/><br /><sub><b>洪月阳</b></sub></a><br /><a href="https://github.com/iluwatar/java-design-patterns/commits?author=RayYH" title="Code">💻</a></td>
<td align="center"><a href="https://xdvrx1.github.io/"><img src="https://avatars0.githubusercontent.com/u/47092464?v=4?s=100" width="100px;" alt=""/><br /><sub><b>xdvrx1</b></sub></a><br /><a href="https://github.com/iluwatar/java-design-patterns/pulls?q=is%3Apr+reviewed-by%3Axdvrx1" title="Reviewed Pull Requests">👀</a> <a href="#ideas-xdvrx1" title="Ideas, Planning, & Feedback">🤔</a></td> <td align="center"><a href="https://xdvrx1.github.io/"><img src="https://avatars0.githubusercontent.com/u/47092464?v=4?s=100" width="100px;" alt=""/><br /><sub><b>xdvrx1</b></sub></a><br /><a href="https://github.com/iluwatar/java-design-patterns/pulls?q=is%3Apr+reviewed-by%3Axdvrx1" title="Reviewed Pull Requests">👀</a> <a href="#ideas-xdvrx1" title="Ideas, Planning, & Feedback">🤔</a></td>
<td align="center"><a href="https://github.com/nahteb"><img src="https://avatars3.githubusercontent.com/u/13121570?v=4?s=100" width="100px;" alt=""/><br /><sub><b>Bethan Palmer</b></sub></a><br /><a href="https://github.com/iluwatar/java-design-patterns/commits?author=nahteb" title="Code">💻</a></td> <td align="center"><a href="http://subho.xyz"><img src="https://avatars0.githubusercontent.com/u/13291222?v=4?s=100" width="100px;" alt=""/><br /><sub><b>Subhrodip Mohanta</b></sub></a><br /><a href="https://github.com/iluwatar/java-design-patterns/commits?author=ohbus" title="Code">💻</a> <a href="https://github.com/iluwatar/java-design-patterns/pulls?q=is%3Apr+reviewed-by%3Aohbus" title="Reviewed Pull Requests">👀</a></td>
<td align="center"><a href="https://github.com/ToxicDreamz"><img src="https://avatars0.githubusercontent.com/u/45225562?v=4?s=100" width="100px;" alt=""/><br /><sub><b>Toxic Dreamz</b></sub></a><br /><a href="https://github.com/iluwatar/java-design-patterns/commits?author=ToxicDreamz" title="Code">💻</a></td>
</tr> </tr>
<tr> <tr>
<td align="center"><a href="https://github.com/nahteb"><img src="https://avatars3.githubusercontent.com/u/13121570?v=4?s=100" width="100px;" alt=""/><br /><sub><b>Bethan Palmer</b></sub></a><br /><a href="https://github.com/iluwatar/java-design-patterns/commits?author=nahteb" title="Code">💻</a></td>
<td align="center"><a href="https://github.com/ToxicDreamz"><img src="https://avatars0.githubusercontent.com/u/45225562?v=4?s=100" width="100px;" alt=""/><br /><sub><b>Toxic Dreamz</b></sub></a><br /><a href="https://github.com/iluwatar/java-design-patterns/commits?author=ToxicDreamz" title="Code">💻</a></td>
<td align="center"><a href="http://www.edycutjong.com"><img src="https://avatars1.githubusercontent.com/u/1098102?v=4?s=100" width="100px;" alt=""/><br /><sub><b>Edy Cu Tjong</b></sub></a><br /><a href="https://github.com/iluwatar/java-design-patterns/commits?author=edycutjong" title="Documentation">📖</a></td> <td align="center"><a href="http://www.edycutjong.com"><img src="https://avatars1.githubusercontent.com/u/1098102?v=4?s=100" width="100px;" alt=""/><br /><sub><b>Edy Cu Tjong</b></sub></a><br /><a href="https://github.com/iluwatar/java-design-patterns/commits?author=edycutjong" title="Documentation">📖</a></td>
<td align="center"><a href="https://github.com/mkrzywanski"><img src="https://avatars0.githubusercontent.com/u/15279585?v=4?s=100" width="100px;" alt=""/><br /><sub><b>Michał Krzywański</b></sub></a><br /><a href="https://github.com/iluwatar/java-design-patterns/commits?author=mkrzywanski" title="Code">💻</a></td> <td align="center"><a href="https://github.com/mkrzywanski"><img src="https://avatars0.githubusercontent.com/u/15279585?v=4?s=100" width="100px;" alt=""/><br /><sub><b>Michał Krzywański</b></sub></a><br /><a href="https://github.com/iluwatar/java-design-patterns/commits?author=mkrzywanski" title="Code">💻</a></td>
</tr>
<tr>
<td align="center"><a href="https://www.stefan-birkner.de"><img src="https://avatars1.githubusercontent.com/u/711349?v=4?s=100" width="100px;" alt=""/><br /><sub><b>Stefan Birkner</b></sub></a><br /><a href="https://github.com/iluwatar/java-design-patterns/commits?author=stefanbirkner" title="Code">💻</a></td> <td align="center"><a href="https://www.stefan-birkner.de"><img src="https://avatars1.githubusercontent.com/u/711349?v=4?s=100" width="100px;" alt=""/><br /><sub><b>Stefan Birkner</b></sub></a><br /><a href="https://github.com/iluwatar/java-design-patterns/commits?author=stefanbirkner" title="Code">💻</a></td>
<td align="center"><a href="https://github.com/fedorskvorcov"><img src="https://avatars3.githubusercontent.com/u/43882212?v=4?s=100" width="100px;" alt=""/><br /><sub><b>Fedor Skvorcov</b></sub></a><br /><a href="https://github.com/iluwatar/java-design-patterns/commits?author=fedorskvorcov" title="Code">💻</a></td> <td align="center"><a href="https://github.com/fedorskvorcov"><img src="https://avatars3.githubusercontent.com/u/43882212?v=4?s=100" width="100px;" alt=""/><br /><sub><b>Fedor Skvorcov</b></sub></a><br /><a href="https://github.com/iluwatar/java-design-patterns/commits?author=fedorskvorcov" title="Code">💻</a></td>
<td align="center"><a href="https://github.com/samilAyoub"><img src="https://avatars0.githubusercontent.com/u/61546990?v=4?s=100" width="100px;" alt=""/><br /><sub><b>samilAyoub</b></sub></a><br /><a href="https://github.com/iluwatar/java-design-patterns/commits?author=samilAyoub" title="Code">💻</a></td> <td align="center"><a href="https://github.com/samilAyoub"><img src="https://avatars0.githubusercontent.com/u/61546990?v=4?s=100" width="100px;" alt=""/><br /><sub><b>samilAyoub</b></sub></a><br /><a href="https://github.com/iluwatar/java-design-patterns/commits?author=samilAyoub" title="Code">💻</a></td>
<td align="center"><a href="https://github.com/vdlald"><img src="https://avatars0.githubusercontent.com/u/29997701?v=4?s=100" width="100px;" alt=""/><br /><sub><b>Vladislav Golubinov</b></sub></a><br /><a href="https://github.com/iluwatar/java-design-patterns/commits?author=vdlald" title="Code">💻</a></td> <td align="center"><a href="https://github.com/vdlald"><img src="https://avatars0.githubusercontent.com/u/29997701?v=4?s=100" width="100px;" alt=""/><br /><sub><b>Vladislav Golubinov</b></sub></a><br /><a href="https://github.com/iluwatar/java-design-patterns/commits?author=vdlald" title="Code">💻</a></td>
<td align="center"><a href="https://github.com/swarajsaaj"><img src="https://avatars2.githubusercontent.com/u/6285049?v=4?s=100" width="100px;" alt=""/><br /><sub><b>Swaraj</b></sub></a><br /><a href="https://github.com/iluwatar/java-design-patterns/commits?author=swarajsaaj" title="Code">💻</a></td>
</tr> </tr>
<tr> <tr>
<td align="center"><a href="https://github.com/swarajsaaj"><img src="https://avatars2.githubusercontent.com/u/6285049?v=4?s=100" width="100px;" alt=""/><br /><sub><b>Swaraj</b></sub></a><br /><a href="https://github.com/iluwatar/java-design-patterns/commits?author=swarajsaaj" title="Code">💻</a></td>
<td align="center"><a href="http://christophflick.de"><img src="https://avatars0.githubusercontent.com/u/4465376?v=4?s=100" width="100px;" alt=""/><br /><sub><b>Christoph Flick</b></sub></a><br /><a href="https://github.com/iluwatar/java-design-patterns/commits?author=ChFlick" title="Documentation">📖</a></td> <td align="center"><a href="http://christophflick.de"><img src="https://avatars0.githubusercontent.com/u/4465376?v=4?s=100" width="100px;" alt=""/><br /><sub><b>Christoph Flick</b></sub></a><br /><a href="https://github.com/iluwatar/java-design-patterns/commits?author=ChFlick" title="Documentation">📖</a></td>
<td align="center"><a href="https://github.com/Ascenio"><img src="https://avatars1.githubusercontent.com/u/7662016?v=4?s=100" width="100px;" alt=""/><br /><sub><b>Ascênio</b></sub></a><br /><a href="https://github.com/iluwatar/java-design-patterns/pulls?q=is%3Apr+reviewed-by%3AAscenio" title="Reviewed Pull Requests">👀</a></td> <td align="center"><a href="https://github.com/Ascenio"><img src="https://avatars1.githubusercontent.com/u/7662016?v=4?s=100" width="100px;" alt=""/><br /><sub><b>Ascênio</b></sub></a><br /><a href="https://github.com/iluwatar/java-design-patterns/pulls?q=is%3Apr+reviewed-by%3AAscenio" title="Reviewed Pull Requests">👀</a></td>
<td align="center"><a href="https://www.linkedin.com/in/domenico-sibilio/"><img src="https://avatars2.githubusercontent.com/u/24280982?v=4?s=100" width="100px;" alt=""/><br /><sub><b>Domenico Sibilio</b></sub></a><br /><a href="https://github.com/iluwatar/java-design-patterns/commits?author=dsibilio" title="Documentation">📖</a></td> <td align="center"><a href="https://www.linkedin.com/in/domenico-sibilio/"><img src="https://avatars2.githubusercontent.com/u/24280982?v=4?s=100" width="100px;" alt=""/><br /><sub><b>Domenico Sibilio</b></sub></a><br /><a href="https://github.com/iluwatar/java-design-patterns/commits?author=dsibilio" title="Documentation">📖</a></td>
</tr>
<tr>
<td align="center"><a href="https://github.com/akashchandwani"><img src="https://avatars2.githubusercontent.com/u/3483277?v=4?s=100" width="100px;" alt=""/><br /><sub><b>Akash Chandwani</b></sub></a><br /><a href="https://github.com/iluwatar/java-design-patterns/pulls?q=is%3Apr+reviewed-by%3Aakashchandwani" title="Reviewed Pull Requests">👀</a></td> <td align="center"><a href="https://github.com/akashchandwani"><img src="https://avatars2.githubusercontent.com/u/3483277?v=4?s=100" width="100px;" alt=""/><br /><sub><b>Akash Chandwani</b></sub></a><br /><a href="https://github.com/iluwatar/java-design-patterns/pulls?q=is%3Apr+reviewed-by%3Aakashchandwani" title="Reviewed Pull Requests">👀</a></td>
<td align="center"><a href="http://www.linkedin.com/in/manannikov"><img src="https://avatars2.githubusercontent.com/u/7019769?v=4?s=100" width="100px;" alt=""/><br /><sub><b>Pavlo Manannikov</b></sub></a><br /><a href="https://github.com/iluwatar/java-design-patterns/commits?author=manannikov" title="Code">💻</a></td> <td align="center"><a href="http://www.linkedin.com/in/manannikov"><img src="https://avatars2.githubusercontent.com/u/7019769?v=4?s=100" width="100px;" alt=""/><br /><sub><b>Pavlo Manannikov</b></sub></a><br /><a href="https://github.com/iluwatar/java-design-patterns/commits?author=manannikov" title="Code">💻</a></td>
<td align="center"><a href="https://github.com/eimanip"><img src="https://avatars0.githubusercontent.com/u/20307301?v=4?s=100" width="100px;" alt=""/><br /><sub><b>Eiman</b></sub></a><br /><a href="https://github.com/iluwatar/java-design-patterns/commits?author=eimanip" title="Code">💻</a></td> <td align="center"><a href="https://github.com/eimanip"><img src="https://avatars0.githubusercontent.com/u/20307301?v=4?s=100" width="100px;" alt=""/><br /><sub><b>Eiman</b></sub></a><br /><a href="https://github.com/iluwatar/java-design-patterns/commits?author=eimanip" title="Code">💻</a></td>
@ -260,76 +290,28 @@ This project is licensed under the terms of the MIT license.
<td align="center"><a href="https://github.com/gkulkarni2020"><img src="https://avatars3.githubusercontent.com/u/5161548?v=4?s=100" width="100px;" alt=""/><br /><sub><b>Girish Kulkarni</b></sub></a><br /><a href="https://github.com/iluwatar/java-design-patterns/commits?author=gkulkarni2020" title="Documentation">📖</a></td> <td align="center"><a href="https://github.com/gkulkarni2020"><img src="https://avatars3.githubusercontent.com/u/5161548?v=4?s=100" width="100px;" alt=""/><br /><sub><b>Girish Kulkarni</b></sub></a><br /><a href="https://github.com/iluwatar/java-design-patterns/commits?author=gkulkarni2020" title="Documentation">📖</a></td>
<td align="center"><a href="https://github.com/omk13"><img src="https://avatars0.githubusercontent.com/u/59054172?v=4?s=100" width="100px;" alt=""/><br /><sub><b>Omar Karazoun</b></sub></a><br /><a href="https://github.com/iluwatar/java-design-patterns/commits?author=omk13" title="Code">💻</a></td> <td align="center"><a href="https://github.com/omk13"><img src="https://avatars0.githubusercontent.com/u/59054172?v=4?s=100" width="100px;" alt=""/><br /><sub><b>Omar Karazoun</b></sub></a><br /><a href="https://github.com/iluwatar/java-design-patterns/commits?author=omk13" title="Code">💻</a></td>
<td align="center"><a href="https://github.com/jeff303"><img src="https://avatars0.githubusercontent.com/u/3521562?v=4?s=100" width="100px;" alt=""/><br /><sub><b>Jeff Evans</b></sub></a><br /><a href="https://github.com/iluwatar/java-design-patterns/commits?author=jeff303" title="Code">💻</a></td> <td align="center"><a href="https://github.com/jeff303"><img src="https://avatars0.githubusercontent.com/u/3521562?v=4?s=100" width="100px;" alt=""/><br /><sub><b>Jeff Evans</b></sub></a><br /><a href="https://github.com/iluwatar/java-design-patterns/commits?author=jeff303" title="Code">💻</a></td>
</tr>
<tr>
<td align="center"><a href="https://viveksb007.github.io"><img src="https://avatars1.githubusercontent.com/u/12713808?v=4?s=100" width="100px;" alt=""/><br /><sub><b>Vivek Singh</b></sub></a><br /><a href="https://github.com/iluwatar/java-design-patterns/commits?author=viveksb007" title="Code">💻</a></td> <td align="center"><a href="https://viveksb007.github.io"><img src="https://avatars1.githubusercontent.com/u/12713808?v=4?s=100" width="100px;" alt=""/><br /><sub><b>Vivek Singh</b></sub></a><br /><a href="https://github.com/iluwatar/java-design-patterns/commits?author=viveksb007" title="Code">💻</a></td>
<td align="center"><a href="https://github.com/siavashsoleymani"><img src="https://avatars2.githubusercontent.com/u/18074419?v=4?s=100" width="100px;" alt=""/><br /><sub><b>siavash</b></sub></a><br /><a href="https://github.com/iluwatar/java-design-patterns/commits?author=siavashsoleymani" title="Code">💻</a></td> <td align="center"><a href="https://github.com/siavashsoleymani"><img src="https://avatars2.githubusercontent.com/u/18074419?v=4?s=100" width="100px;" alt=""/><br /><sub><b>siavash</b></sub></a><br /><a href="https://github.com/iluwatar/java-design-patterns/commits?author=siavashsoleymani" title="Code">💻</a></td>
<td align="center"><a href="https://github.com/ruchpeanuts"><img src="https://avatars0.githubusercontent.com/u/29301900?v=4?s=100" width="100px;" alt=""/><br /><sub><b>ruchpeanuts</b></sub></a><br /><a href="https://github.com/iluwatar/java-design-patterns/commits?author=ruchpeanuts" title="Documentation">📖</a></td> <td align="center"><a href="https://github.com/ruchpeanuts"><img src="https://avatars0.githubusercontent.com/u/29301900?v=4?s=100" width="100px;" alt=""/><br /><sub><b>ruchpeanuts</b></sub></a><br /><a href="https://github.com/iluwatar/java-design-patterns/commits?author=ruchpeanuts" title="Documentation">📖</a></td>
<td align="center"><a href="https://github.com/warp125"><img src="https://avatars1.githubusercontent.com/u/48073115?v=4?s=100" width="100px;" alt=""/><br /><sub><b>warp125</b></sub></a><br /><a href="#translation-warp125" title="Translation">🌍</a></td>
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<td align="center"><a href="https://github.com/warp125"><img src="https://avatars1.githubusercontent.com/u/48073115?v=4?s=100" width="100px;" alt=""/><br /><sub><b>warp125</b></sub></a><br /><a href="#translation-warp125" title="Translation">🌍</a></td>
<td align="center"><a href="http://libkhadir.fr"><img src="https://avatars1.githubusercontent.com/u/45130488?v=4?s=100" width="100px;" alt=""/><br /><sub><b>KHADIR Tayeb</b></sub></a><br /><a href="#translation-tkhadir" title="Translation">🌍</a></td> <td align="center"><a href="http://libkhadir.fr"><img src="https://avatars1.githubusercontent.com/u/45130488?v=4?s=100" width="100px;" alt=""/><br /><sub><b>KHADIR Tayeb</b></sub></a><br /><a href="#translation-tkhadir" title="Translation">🌍</a></td>
<td align="center"><a href="https://github.com/ignite1771"><img src="https://avatars2.githubusercontent.com/u/59446563?v=4?s=100" width="100px;" alt=""/><br /><sub><b>ignite1771</b></sub></a><br /><a href="https://github.com/iluwatar/java-design-patterns/commits?author=ignite1771" title="Code">💻</a></td> <td align="center"><a href="https://github.com/ignite1771"><img src="https://avatars2.githubusercontent.com/u/59446563?v=4?s=100" width="100px;" alt=""/><br /><sub><b>ignite1771</b></sub></a><br /><a href="https://github.com/iluwatar/java-design-patterns/commits?author=ignite1771" title="Code">💻</a></td>
<td align="center"><a href="https://github.com/demirhalil"><img src="https://avatars1.githubusercontent.com/u/22895118?v=4?s=100" width="100px;" alt=""/><br /><sub><b>Halil Demir</b></sub></a><br /><a href="#translation-demirhalil" title="Translation">🌍</a></td> <td align="center"><a href="https://github.com/demirhalil"><img src="https://avatars1.githubusercontent.com/u/22895118?v=4?s=100" width="100px;" alt=""/><br /><sub><b>Halil Demir</b></sub></a><br /><a href="#translation-demirhalil" title="Translation">🌍</a></td>
<td align="center"><a href="https://github.com/rohit10000"><img src="https://avatars.githubusercontent.com/u/20845565?v=4?s=100" width="100px;" alt=""/><br /><sub><b>Rohit Singh</b></sub></a><br /><a href="https://github.com/iluwatar/java-design-patterns/commits?author=rohit10000" title="Code">💻</a></td> <td align="center"><a href="https://github.com/rohit10000"><img src="https://avatars.githubusercontent.com/u/20845565?v=4?s=100" width="100px;" alt=""/><br /><sub><b>Rohit Singh</b></sub></a><br /><a href="https://github.com/iluwatar/java-design-patterns/commits?author=rohit10000" title="Code">💻</a></td>
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<td align="center"><a href="https://github.com/byoungju94"><img src="https://avatars.githubusercontent.com/u/42516378?v=4?s=100" width="100px;" alt=""/><br /><sub><b>byoungju94</b></sub></a><br /><a href="https://github.com/iluwatar/java-design-patterns/commits?author=byoungju94" title="Code">💻</a></td> <td align="center"><a href="https://github.com/byoungju94"><img src="https://avatars.githubusercontent.com/u/42516378?v=4?s=100" width="100px;" alt=""/><br /><sub><b>byoungju94</b></sub></a><br /><a href="https://github.com/iluwatar/java-design-patterns/commits?author=byoungju94" title="Code">💻</a></td>
<td align="center"><a href="https://github.com/moustafafarhat"><img src="https://avatars.githubusercontent.com/u/38836727?v=4?s=100" width="100px;" alt=""/><br /><sub><b>Moustafa Farhat</b></sub></a><br /><a href="#translation-moustafafarhat" title="Translation">🌍</a></td> <td align="center"><a href="https://github.com/moustafafarhat"><img src="https://avatars.githubusercontent.com/u/38836727?v=4?s=100" width="100px;" alt=""/><br /><sub><b>Moustafa Farhat</b></sub></a><br /><a href="#translation-moustafafarhat" title="Translation">🌍</a></td>
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<td align="center"><a href="https://github.com/richardmr36"><img src="https://avatars.githubusercontent.com/u/19147333?v=4?s=100" width="100px;" alt=""/><br /><sub><b>Martel Richard</b></sub></a><br /><a href="https://github.com/iluwatar/java-design-patterns/commits?author=richardmr36" title="Code">💻</a></td> <td align="center"><a href="https://github.com/richardmr36"><img src="https://avatars.githubusercontent.com/u/19147333?v=4?s=100" width="100px;" alt=""/><br /><sub><b>Martel Richard</b></sub></a><br /><a href="https://github.com/iluwatar/java-design-patterns/commits?author=richardmr36" title="Code">💻</a></td>
<td align="center"><a href="https://github.com/va1m"><img src="https://avatars.githubusercontent.com/u/17025445?v=4?s=100" width="100px;" alt=""/><br /><sub><b>va1m</b></sub></a><br /><a href="https://github.com/iluwatar/java-design-patterns/commits?author=va1m" title="Code">💻</a></td> <td align="center"><a href="https://github.com/va1m"><img src="https://avatars.githubusercontent.com/u/17025445?v=4?s=100" width="100px;" alt=""/><br /><sub><b>va1m</b></sub></a><br /><a href="https://github.com/iluwatar/java-design-patterns/commits?author=va1m" title="Code">💻</a></td>
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<td align="center"><a href="https://github.com/noamgrinch"><img src="https://avatars.githubusercontent.com/u/31648669?v=4?s=100" width="100px;" alt=""/><br /><sub><b>Noam Greenshtain</b></sub></a><br /><a href="https://github.com/iluwatar/java-design-patterns/commits?author=noamgrinch" title="Code">💻</a></td> <td align="center"><a href="https://github.com/noamgrinch"><img src="https://avatars.githubusercontent.com/u/31648669?v=4?s=100" width="100px;" alt=""/><br /><sub><b>Noam Greenshtain</b></sub></a><br /><a href="https://github.com/iluwatar/java-design-patterns/commits?author=noamgrinch" title="Code">💻</a></td>
<td align="center"><a href="https://xuyonghong.cn/"><img src="https://avatars.githubusercontent.com/u/14086462?v=4?s=100" width="100px;" alt=""/><br /><sub><b>yonghong Xu</b></sub></a><br /><a href="https://github.com/iluwatar/java-design-patterns/commits?author=qfxl" title="Documentation">📖</a></td> <td align="center"><a href="https://xuyonghong.cn/"><img src="https://avatars.githubusercontent.com/u/14086462?v=4?s=100" width="100px;" alt=""/><br /><sub><b>yonghong Xu</b></sub></a><br /><a href="https://github.com/iluwatar/java-design-patterns/commits?author=qfxl" title="Documentation">📖</a></td>
<td align="center"><a href="https://www.linkedin.com/in/jinisha-vora"><img src="https://avatars.githubusercontent.com/u/40777762?v=4?s=100" width="100px;" alt=""/><br /><sub><b>jinishavora</b></sub></a><br /><a href="https://github.com/iluwatar/java-design-patterns/pulls?q=is%3Apr+reviewed-by%3Ajinishavora" title="Reviewed Pull Requests">👀</a> <a href="https://github.com/iluwatar/java-design-patterns/commits?author=jinishavora" title="Code">💻</a></td>
<td align="center"><a href="https://github.com/eas5"><img src="https://avatars.githubusercontent.com/u/50836521?v=4?s=100" width="100px;" alt=""/><br /><sub><b>Elvys Soares</b></sub></a><br /><a href="https://github.com/iluwatar/java-design-patterns/commits?author=eas5" title="Code">💻</a></td>
<td align="center"><a href="https://github.com/zWeBrain"><img src="https://avatars.githubusercontent.com/u/46642512?v=4?s=100" width="100px;" alt=""/><br /><sub><b>zWeBrain</b></sub></a><br /><a href="https://github.com/iluwatar/java-design-patterns/commits?author=zWeBrain" title="Code">💻</a></td>
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<td align="center"><a href="https://al-assad.github.io/notion/"><img src="https://avatars.githubusercontent.com/u/22493821?v=4?s=100" width="100px;" alt=""/><br /><sub><b>余林颖</b></sub></a><br /><a href="#translation-Al-assad" title="Translation">🌍</a></td>
<td align="center"><a href="https://github.com/STudio26"><img src="https://avatars.githubusercontent.com/u/6988911?v=4?s=100" width="100px;" alt=""/><br /><sub><b>Alain</b></sub></a><br /><a href="#translation-STudio26" title="Translation">🌍</a></td>
<td align="center"><a href="https://github.com/DEV-VRUPER"><img src="https://avatars.githubusercontent.com/u/30525467?v=4?s=100" width="100px;" alt=""/><br /><sub><b>VR</b></sub></a><br /><a href="https://github.com/iluwatar/java-design-patterns/commits?author=DEV-VRUPER" title="Documentation">📖</a></td>
<td align="center"><a href="https://github.com/JackieNim"><img src="https://avatars.githubusercontent.com/u/4138836?v=4?s=100" width="100px;" alt=""/><br /><sub><b>JackieNim</b></sub></a><br /><a href="https://github.com/iluwatar/java-design-patterns/commits?author=JackieNim" title="Code">💻</a></td>
<td align="center"><a href="https://github.com/EdisonE3"><img src="https://avatars.githubusercontent.com/u/52118917?v=4?s=100" width="100px;" alt=""/><br /><sub><b>EdisonE3</b></sub></a><br /><a href="https://github.com/iluwatar/java-design-patterns/commits?author=EdisonE3" title="Code">💻</a></td>
<td align="center"><a href="https://github.com/tao-sun2"><img src="https://avatars.githubusercontent.com/u/66189688?v=4?s=100" width="100px;" alt=""/><br /><sub><b>Tao</b></sub></a><br /><a href="https://github.com/iluwatar/java-design-patterns/commits?author=tao-sun2" title="Code">💻</a></td>
<td align="center"><a href="https://github.com/JuanManuelAbate"><img src="https://avatars.githubusercontent.com/u/16357060?v=4?s=100" width="100px;" alt=""/><br /><sub><b>Juan Manuel Abate</b></sub></a><br /><a href="#translation-JuanManuelAbate" title="Translation">🌍</a></td>
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<td align="center"><a href="https://github.com/Xenilo137"><img src="https://avatars.githubusercontent.com/u/24865069?v=4?s=100" width="100px;" alt=""/><br /><sub><b>Xenilo137</b></sub></a><br /><a href="https://github.com/iluwatar/java-design-patterns/commits?author=Xenilo137" title="Code">💻</a></td>
<td align="center"><a href="https://www.linkedin.com/in/souzasamuel/"><img src="https://avatars.githubusercontent.com/u/17254162?v=4?s=100" width="100px;" alt=""/><br /><sub><b>Samuel Souza</b></sub></a><br /><a href="https://github.com/iluwatar/java-design-patterns/commits?author=samuelpsouza" title="Code">💻</a></td>
<td align="center"><a href="https://github.com/marlo2222"><img src="https://avatars.githubusercontent.com/u/40809563?v=4?s=100" width="100px;" alt=""/><br /><sub><b>Marlo Henrique</b></sub></a><br /><a href="#translation-marlo2222" title="Translation">🌍</a></td>
<td align="center"><a href="https://github.com/AndriyPyzh"><img src="https://avatars.githubusercontent.com/u/57706635?v=4?s=100" width="100px;" alt=""/><br /><sub><b>AndriyPyzh</b></sub></a><br /><a href="https://github.com/iluwatar/java-design-patterns/commits?author=AndriyPyzh" title="Code">💻</a></td>
<td align="center"><a href="https://github.com/karthikbhat13"><img src="https://avatars.githubusercontent.com/u/22431014?v=4?s=100" width="100px;" alt=""/><br /><sub><b>karthikbhat13</b></sub></a><br /><a href="https://github.com/iluwatar/java-design-patterns/commits?author=karthikbhat13" title="Code">💻</a></td>
<td align="center"><a href="https://github.com/mortezaadi"><img src="https://avatars.githubusercontent.com/u/1329687?v=4?s=100" width="100px;" alt=""/><br /><sub><b>Morteza Adigozalpour</b></sub></a><br /><a href="https://github.com/iluwatar/java-design-patterns/commits?author=mortezaadi" title="Code">💻</a></td>
<td align="center"><a href="https://stackoverflow.com/users/308565/nagaraj-tantri"><img src="https://avatars.githubusercontent.com/u/3784194?v=4?s=100" width="100px;" alt=""/><br /><sub><b>Nagaraj Tantri</b></sub></a><br /><a href="https://github.com/iluwatar/java-design-patterns/commits?author=tan31989" title="Code">💻</a></td>
</tr>
<tr>
<td align="center"><a href="http://scuccimarri.it"><img src="https://avatars.githubusercontent.com/u/7107651?v=4?s=100" width="100px;" alt=""/><br /><sub><b>Francesco Scuccimarri</b></sub></a><br /><a href="https://github.com/iluwatar/java-design-patterns/commits?author=frascu" title="Code">💻</a></td>
<td align="center"><a href="https://github.com/Conhan93"><img src="https://avatars.githubusercontent.com/u/71334757?v=4?s=100" width="100px;" alt=""/><br /><sub><b>Conny Hansson</b></sub></a><br /><a href="https://github.com/iluwatar/java-design-patterns/commits?author=Conhan93" title="Documentation">📖</a></td>
<td align="center"><a href="http://muklasr.medium.com"><img src="https://avatars.githubusercontent.com/u/43443753?v=4?s=100" width="100px;" alt=""/><br /><sub><b>Muklas Rahmanto</b></sub></a><br /><a href="#translation-muklasr" title="Translation">🌍</a></td>
<td align="center"><a href="https://github.com/VxDxK"><img src="https://avatars.githubusercontent.com/u/38704817?v=4?s=100" width="100px;" alt=""/><br /><sub><b>Vadim</b></sub></a><br /><a href="#translation-VxDxK" title="Translation">🌍</a></td>
<td align="center"><a href="https://github.com/sims-keshri"><img src="https://avatars.githubusercontent.com/u/62168475?v=4?s=100" width="100px;" alt=""/><br /><sub><b>Simran Keshri</b></sub></a><br /><a href="https://github.com/iluwatar/java-design-patterns/commits?author=sims-keshri" title="Code">💻</a></td>
<td align="center"><a href="https://programacionymas.com"><img src="https://avatars.githubusercontent.com/u/3101238?v=4?s=100" width="100px;" alt=""/><br /><sub><b>JCarlos</b></sub></a><br /><a href="#translation-JCarlosR" title="Translation">🌍</a></td>
<td align="center"><a href="https://www.mrmoshkel.ir"><img src="https://avatars.githubusercontent.com/u/60359433?v=4?s=100" width="100px;" alt=""/><br /><sub><b>Ali Ghasemi</b></sub></a><br /><a href="https://github.com/iluwatar/java-design-patterns/commits?author=Dev-AliGhasemi" title="Code">💻</a></td>
</tr>
<tr>
<td align="center"><a href="http://carlfx.wordpress.com"><img src="https://avatars.githubusercontent.com/u/1594624?v=4?s=100" width="100px;" alt=""/><br /><sub><b>Carl Dea</b></sub></a><br /><a href="https://github.com/iluwatar/java-design-patterns/commits?author=carldea" title="Code">💻</a></td>
<td align="center"><a href="https://github.com/Mozartuss"><img src="https://avatars.githubusercontent.com/u/32893711?v=4?s=100" width="100px;" alt=""/><br /><sub><b>Mozartus</b></sub></a><br /><a href="#translation-Mozartuss" title="Translation">🌍</a></td>
<td align="center"><a href="https://github.com/ManviGoel26"><img src="https://avatars.githubusercontent.com/u/55682355?v=4?s=100" width="100px;" alt=""/><br /><sub><b>Manvi Goel</b></sub></a><br /><a href="https://github.com/iluwatar/java-design-patterns/commits?author=ManviGoel26" title="Documentation">📖</a></td>
<td align="center"><a href="https://github.com/blueberry404"><img src="https://avatars.githubusercontent.com/u/39243539?v=4?s=100" width="100px;" alt=""/><br /><sub><b>Anum Amin</b></sub></a><br /><a href="https://github.com/iluwatar/java-design-patterns/commits?author=blueberry404" title="Documentation">📖</a></td>
<td align="center"><a href="https://uh-zz.github.io/blog/"><img src="https://avatars.githubusercontent.com/u/47747828?v=4?s=100" width="100px;" alt=""/><br /><sub><b>Reo Uehara</b></sub></a><br /><a href="#translation-uh-zz" title="Translation">🌍</a></td>
<td align="center"><a href="https://github.com/Fiordy"><img src="https://avatars.githubusercontent.com/u/53420573?v=4?s=100" width="100px;" alt=""/><br /><sub><b>Fiordy</b></sub></a><br /><a href="https://github.com/iluwatar/java-design-patterns/commits?author=Fiordy" title="Documentation">📖</a></td>
<td align="center"><a href="https://github.com/harshalkh"><img src="https://avatars.githubusercontent.com/u/37841724?v=4?s=100" width="100px;" alt=""/><br /><sub><b>Harshal</b></sub></a><br /><a href="https://github.com/iluwatar/java-design-patterns/commits?author=harshalkh" title="Code">💻</a></td>
</tr>
<tr>
<td align="center"><a href="https://www.linkedin.com/in/abhinav-vashisth-06613b208/"><img src="https://avatars.githubusercontent.com/u/89785800?v=4?s=100" width="100px;" alt=""/><br /><sub><b>Abhinav Vashisth</b></sub></a><br /><a href="https://github.com/iluwatar/java-design-patterns/commits?author=vashisthabhinav" title="Documentation">📖</a></td>
<td align="center"><a href="http://no website"><img src="https://avatars.githubusercontent.com/u/47126749?v=4?s=100" width="100px;" alt=""/><br /><sub><b>Kevin</b></sub></a><br /><a href="https://github.com/iluwatar/java-design-patterns/pulls?q=is%3Apr+reviewed-by%3AKevinyl3" title="Reviewed Pull Requests">👀</a> <a href="https://github.com/iluwatar/java-design-patterns/commits?author=Kevinyl3" title="Code">💻</a></td>
<td align="center"><a href="https://github.com/Shrirang97"><img src="https://avatars.githubusercontent.com/u/28738668?v=4?s=100" width="100px;" alt=""/><br /><sub><b>Shrirang</b></sub></a><br /><a href="https://github.com/iluwatar/java-design-patterns/pulls?q=is%3Apr+reviewed-by%3AShrirang97" title="Reviewed Pull Requests">👀</a> <a href="https://github.com/iluwatar/java-design-patterns/commits?author=Shrirang97" title="Code">💻</a></td>
<td align="center"><a href="https://github.com/interactwithankush"><img src="https://avatars.githubusercontent.com/u/18613127?v=4?s=100" width="100px;" alt=""/><br /><sub><b>interactwithankush</b></sub></a><br /><a href="https://github.com/iluwatar/java-design-patterns/commits?author=interactwithankush" title="Code">💻</a></td>
<td align="center"><a href="https://github.com/yuhangbin"><img src="https://avatars.githubusercontent.com/u/17566866?v=4?s=100" width="100px;" alt=""/><br /><sub><b>CharlieYu</b></sub></a><br /><a href="https://github.com/iluwatar/java-design-patterns/commits?author=yuhangbin" title="Code">💻</a></td>
<td align="center"><a href="https://github.com/Leisterbecker"><img src="https://avatars.githubusercontent.com/u/20650323?v=4?s=100" width="100px;" alt=""/><br /><sub><b>Leisterbecker</b></sub></a><br /><a href="https://github.com/iluwatar/java-design-patterns/commits?author=Leisterbecker" title="Code">💻</a></td>
<td align="center"><a href="http://rosaecrucis.cn"><img src="https://avatars.githubusercontent.com/u/35420129?v=4?s=100" width="100px;" alt=""/><br /><sub><b>DragonDreamer</b></sub></a><br /><a href="https://github.com/iluwatar/java-design-patterns/commits?author=castleKing1997" title="Code">💻</a></td>
</tr>
<tr>
<td align="center"><a href="https://github.com/ShivanshCharak"><img src="https://avatars.githubusercontent.com/u/96943825?v=4?s=100" width="100px;" alt=""/><br /><sub><b>ShivanshCharak</b></sub></a><br /><a href="https://github.com/iluwatar/java-design-patterns/commits?author=ShivanshCharak" title="Code">💻</a></td>
<td align="center"><a href="https://github.com/HattoriHenzo"><img src="https://avatars.githubusercontent.com/u/5141285?v=4?s=100" width="100px;" alt=""/><br /><sub><b>HattoriHenzo</b></sub></a><br /><a href="https://github.com/iluwatar/java-design-patterns/commits?author=HattoriHenzo" title="Code">💻</a></td>
</tr> </tr>
</table> </table>

View File

@ -4,7 +4,6 @@ title: Abstract Document
folder: abstract-document folder: abstract-document
permalink: /patterns/abstract-document/ permalink: /patterns/abstract-document/
categories: Structural categories: Structural
language: en
tags: tags:
- Extensibility - Extensibility
--- ---

View File

@ -23,40 +23,42 @@
THE SOFTWARE. THE SOFTWARE.
--> -->
<project xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd"> <project xmlns="http://maven.apache.org/POM/4.0.0"
<modelVersion>4.0.0</modelVersion> xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
<parent> xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
<artifactId>java-design-patterns</artifactId> <modelVersion>4.0.0</modelVersion>
<groupId>com.iluwatar</groupId> <parent>
<version>1.26.0-SNAPSHOT</version> <artifactId>java-design-patterns</artifactId>
</parent> <groupId>com.iluwatar</groupId>
<artifactId>abstract-document</artifactId> <version>1.24.0-SNAPSHOT</version>
<dependencies> </parent>
<dependency> <artifactId>abstract-document</artifactId>
<groupId>org.junit.jupiter</groupId> <dependencies>
<artifactId>junit-jupiter-engine</artifactId> <dependency>
<scope>test</scope> <groupId>org.junit.jupiter</groupId>
</dependency> <artifactId>junit-jupiter-engine</artifactId>
</dependencies> <scope>test</scope>
<build> </dependency>
<plugins> </dependencies>
<!-- Maven assembly plugin is invoked with default setting which we have <build>
<plugins>
<!-- Maven assembly plugin is invoked with default setting which we have
in parent pom and specifying the class having main method --> in parent pom and specifying the class having main method -->
<plugin> <plugin>
<groupId>org.apache.maven.plugins</groupId> <groupId>org.apache.maven.plugins</groupId>
<artifactId>maven-assembly-plugin</artifactId> <artifactId>maven-assembly-plugin</artifactId>
<executions> <executions>
<execution> <execution>
<configuration> <configuration>
<archive> <archive>
<manifest> <manifest>
<mainClass>com.iluwatar.abstractdocument.App</mainClass> <mainClass>com.iluwatar.abstractdocument.App</mainClass>
</manifest> </manifest>
</archive> </archive>
</configuration> </configuration>
</execution> </execution>
</executions> </executions>
</plugin> </plugin>
</plugins> </plugins>
</build> </build>
</project> </project>

View File

@ -4,7 +4,6 @@ title: Abstract Factory
folder: abstract-factory folder: abstract-factory
permalink: /patterns/abstract-factory/ permalink: /patterns/abstract-factory/
categories: Creational categories: Creational
language: en
tags: tags:
- Gang of Four - Gang of Four
--- ---
@ -20,9 +19,9 @@ objects without specifying their concrete classes.
## Explanation ## Explanation
Real-world example Real world example
> To create a kingdom we need objects with a common theme. The elven kingdom needs an elven king, elven castle, and elven army whereas the orcish kingdom needs an orcish king, orcish castle, and orcish army. There is a dependency between the objects in the kingdom. > To create a kingdom we need objects with a common theme. Elven kingdom needs an Elven king, Elven castle and Elven army whereas Orcish kingdom needs an Orcish king, Orcish castle and Orcish army. There is a dependency between the objects in the kingdom.
In plain words In plain words
@ -34,7 +33,7 @@ Wikipedia says
**Programmatic Example** **Programmatic Example**
Translating the kingdom example above. First of all, we have some interfaces and implementation for the objects in the Translating the kingdom example above. First of all we have some interfaces and implementation for the objects in the
kingdom. kingdom.
```java ```java
@ -52,21 +51,21 @@ public interface Army {
// Elven implementations -> // Elven implementations ->
public class ElfCastle implements Castle { public class ElfCastle implements Castle {
static final String DESCRIPTION = "This is the elven castle!"; static final String DESCRIPTION = "This is the Elven castle!";
@Override @Override
public String getDescription() { public String getDescription() {
return DESCRIPTION; return DESCRIPTION;
} }
} }
public class ElfKing implements King { public class ElfKing implements King {
static final String DESCRIPTION = "This is the elven king!"; static final String DESCRIPTION = "This is the Elven king!";
@Override @Override
public String getDescription() { public String getDescription() {
return DESCRIPTION; return DESCRIPTION;
} }
} }
public class ElfArmy implements Army { public class ElfArmy implements Army {
static final String DESCRIPTION = "This is the elven Army!"; static final String DESCRIPTION = "This is the Elven Army!";
@Override @Override
public String getDescription() { public String getDescription() {
return DESCRIPTION; return DESCRIPTION;
@ -77,7 +76,7 @@ public class ElfArmy implements Army {
``` ```
Then we have the abstraction and implementations for the kingdom factory. Then we have the abstraction and implementations for the kingdom factory
```java ```java
public interface KingdomFactory { public interface KingdomFactory {
@ -87,43 +86,31 @@ public interface KingdomFactory {
} }
public class ElfKingdomFactory implements KingdomFactory { public class ElfKingdomFactory implements KingdomFactory {
@Override
public Castle createCastle() { public Castle createCastle() {
return new ElfCastle(); return new ElfCastle();
} }
@Override
public King createKing() { public King createKing() {
return new ElfKing(); return new ElfKing();
} }
@Override
public Army createArmy() { public Army createArmy() {
return new ElfArmy(); return new ElfArmy();
} }
} }
public class OrcKingdomFactory implements KingdomFactory { public class OrcKingdomFactory implements KingdomFactory {
@Override
public Castle createCastle() { public Castle createCastle() {
return new OrcCastle(); return new OrcCastle();
} }
@Override
public King createKing() { public King createKing() {
return new OrcKing(); return new OrcKing();
} }
@Override
public Army createArmy() { public Army createArmy() {
return new OrcArmy(); return new OrcArmy();
} }
} }
``` ```
Now we have the abstract factory that lets us make a family of related objects i.e. elven kingdom factory creates elven castle, king and army, etc. Now we have our abstract factory that lets us make family of related objects i.e. Elven kingdom factory creates Elven castle, king and army etc.
```java ```java
var factory = new ElfKingdomFactory(); var factory = new ElfKingdomFactory();
@ -139,13 +126,13 @@ army.getDescription();
Program output: Program output:
```java ```java
This is the elven castle! This is the Elven castle!
This is the elven king! This is the Elven king!
This is the elven Army! This is the Elven Army!
``` ```
Now, we can design a factory for our different kingdom factories. In this example, we created `FactoryMaker`, responsible for returning an instance of either `ElfKingdomFactory` or `OrcKingdomFactory`. Now, we can design a factory for our different kingdom factories. In this example, we created FactoryMaker, responsible for returning an instance of either ElfKingdomFactory or OrcKingdomFactory.
The client can use `FactoryMaker` to create the desired concrete factory which, in turn, will produce different concrete objects (derived from `Army`, `King`, `Castle`). The client can use FactoryMaker to create the desired concrete factory which, in turn, will produce different concrete objects (Army, King, Castle).
In this example, we also used an enum to parameterize which type of kingdom factory the client will ask for. In this example, we also used an enum to parameterize which type of kingdom factory the client will ask for.
```java ```java
@ -191,8 +178,8 @@ public static void main(String[] args) {
Use the Abstract Factory pattern when Use the Abstract Factory pattern when
* The system should be independent of how its products are created, composed, and represented * The system should be independent of how its products are created, composed and represented
* The system should be configured with one of the multiple families of products * The system should be configured with one of multiple families of products
* The family of related product objects is designed to be used together, and you need to enforce this constraint * The family of related product objects is designed to be used together, and you need to enforce this constraint
* You want to provide a class library of products, and you want to reveal just their interfaces, not their implementations * You want to provide a class library of products, and you want to reveal just their interfaces, not their implementations
* The lifetime of the dependency is conceptually shorter than the lifetime of the consumer. * The lifetime of the dependency is conceptually shorter than the lifetime of the consumer.
@ -208,13 +195,13 @@ Example use cases
* Unit test case writing becomes much easier * Unit test case writing becomes much easier
* UI tools for different OS * UI tools for different OS
## Consequences ## Consequences:
* Dependency injection in java hides the service class dependencies that can lead to runtime errors that would have been caught at compile time. * Dependency injection in java hides the service class dependencies that can lead to runtime errors that would have been caught at compile time.
* While the pattern is great when creating predefined objects, adding the new ones might be challenging. * While the pattern is great when creating predefined objects, adding the new ones might be challenging.
* The code becomes more complicated than it should be since a lot of new interfaces and classes are introduced along with the pattern. * The code becomes more complicated than it should be, since a lot of new interfaces and classes are introduced along with the pattern.
## Tutorials ## Tutorial
* [Abstract Factory Pattern Tutorial](https://www.journaldev.com/1418/abstract-factory-design-pattern-in-java) * [Abstract Factory Pattern Tutorial](https://www.journaldev.com/1418/abstract-factory-design-pattern-in-java)

View File

@ -1,4 +1,4 @@
<?xml version="1.0" encoding="UTF-8"?> <?xml version="1.0"?>
<!-- <!--
The MIT License The MIT License
@ -23,40 +23,43 @@
THE SOFTWARE. THE SOFTWARE.
--> -->
<project xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd"> <project
<modelVersion>4.0.0</modelVersion> xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd"
<parent> xmlns="http://maven.apache.org/POM/4.0.0"
<groupId>com.iluwatar</groupId> xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance">
<artifactId>java-design-patterns</artifactId> <modelVersion>4.0.0</modelVersion>
<version>1.26.0-SNAPSHOT</version> <parent>
</parent> <groupId>com.iluwatar</groupId>
<artifactId>abstract-factory</artifactId> <artifactId>java-design-patterns</artifactId>
<dependencies> <version>1.24.0-SNAPSHOT</version>
<dependency> </parent>
<groupId>org.junit.jupiter</groupId> <artifactId>abstract-factory</artifactId>
<artifactId>junit-jupiter-engine</artifactId> <dependencies>
<scope>test</scope> <dependency>
</dependency> <groupId>org.junit.jupiter</groupId>
</dependencies> <artifactId>junit-jupiter-engine</artifactId>
<build> <scope>test</scope>
<plugins> </dependency>
<!-- Maven assembly plugin is invoked with default setting which we have </dependencies>
<build>
<plugins>
<!-- Maven assembly plugin is invoked with default setting which we have
in parent pom and specifying the class having main method --> in parent pom and specifying the class having main method -->
<plugin> <plugin>
<groupId>org.apache.maven.plugins</groupId> <groupId>org.apache.maven.plugins</groupId>
<artifactId>maven-assembly-plugin</artifactId> <artifactId>maven-assembly-plugin</artifactId>
<executions> <executions>
<execution> <execution>
<configuration> <configuration>
<archive> <archive>
<manifest> <manifest>
<mainClass>com.iluwatar.abstractfactory.App</mainClass> <mainClass>com.iluwatar.abstractfactory.App</mainClass>
</manifest> </manifest>
</archive> </archive>
</configuration> </configuration>
</execution> </execution>
</executions> </executions>
</plugin> </plugin>
</plugins> </plugins>
</build> </build>
</project> </project>

View File

@ -37,7 +37,7 @@ import lombok.extern.slf4j.Slf4j;
* *
* <p>The essence of the Abstract Factory pattern is a factory interface ({@link KingdomFactory}) * <p>The essence of the Abstract Factory pattern is a factory interface ({@link KingdomFactory})
* and its implementations ( {@link ElfKingdomFactory}, {@link OrcKingdomFactory}). The example uses * and its implementations ( {@link ElfKingdomFactory}, {@link OrcKingdomFactory}). The example uses
* both concrete implementations to create a king, a castle, and an army. * both concrete implementations to create a king, a castle and an army.
*/ */
@Slf4j @Slf4j
public class App implements Runnable { public class App implements Runnable {
@ -60,13 +60,13 @@ public class App implements Runnable {
@Override @Override
public void run() { public void run() {
LOGGER.info("elf kingdom"); LOGGER.info("Elf Kingdom");
createKingdom(Kingdom.FactoryMaker.KingdomType.ELF); createKingdom(Kingdom.FactoryMaker.KingdomType.ELF);
LOGGER.info(kingdom.getArmy().getDescription()); LOGGER.info(kingdom.getArmy().getDescription());
LOGGER.info(kingdom.getCastle().getDescription()); LOGGER.info(kingdom.getCastle().getDescription());
LOGGER.info(kingdom.getKing().getDescription()); LOGGER.info(kingdom.getKing().getDescription());
LOGGER.info("orc kingdom"); LOGGER.info("Orc Kingdom");
createKingdom(Kingdom.FactoryMaker.KingdomType.ORC); createKingdom(Kingdom.FactoryMaker.KingdomType.ORC);
LOGGER.info(kingdom.getArmy().getDescription()); LOGGER.info(kingdom.getArmy().getDescription());
LOGGER.info(kingdom.getCastle().getDescription()); LOGGER.info(kingdom.getCastle().getDescription());

View File

@ -28,7 +28,7 @@ package com.iluwatar.abstractfactory;
*/ */
public class ElfArmy implements Army { public class ElfArmy implements Army {
static final String DESCRIPTION = "This is the elven army!"; static final String DESCRIPTION = "This is the Elven Army!";
@Override @Override
public String getDescription() { public String getDescription() {

View File

@ -28,7 +28,7 @@ package com.iluwatar.abstractfactory;
*/ */
public class ElfCastle implements Castle { public class ElfCastle implements Castle {
static final String DESCRIPTION = "This is the elven castle!"; static final String DESCRIPTION = "This is the Elven castle!";
@Override @Override
public String getDescription() { public String getDescription() {

View File

@ -28,7 +28,7 @@ package com.iluwatar.abstractfactory;
*/ */
public class ElfKing implements King { public class ElfKing implements King {
static final String DESCRIPTION = "This is the elven king!"; static final String DESCRIPTION = "This is the Elven king!";
@Override @Override
public String getDescription() { public String getDescription() {

View File

@ -28,7 +28,7 @@ package com.iluwatar.abstractfactory;
*/ */
public class OrcArmy implements Army { public class OrcArmy implements Army {
static final String DESCRIPTION = "This is the orc army!"; static final String DESCRIPTION = "This is the Orc Army!";
@Override @Override
public String getDescription() { public String getDescription() {

View File

@ -28,7 +28,7 @@ package com.iluwatar.abstractfactory;
*/ */
public class OrcCastle implements Castle { public class OrcCastle implements Castle {
static final String DESCRIPTION = "This is the orc castle!"; static final String DESCRIPTION = "This is the Orc castle!";
@Override @Override
public String getDescription() { public String getDescription() {

View File

@ -28,7 +28,7 @@ package com.iluwatar.abstractfactory;
*/ */
public class OrcKing implements King { public class OrcKing implements King {
static final String DESCRIPTION = "This is the orc king!"; static final String DESCRIPTION = "This is the Orc king!";
@Override @Override
public String getDescription() { public String getDescription() {

View File

@ -29,14 +29,14 @@ import static org.junit.jupiter.api.Assertions.assertEquals;
import static org.junit.jupiter.api.Assertions.assertTrue; import static org.junit.jupiter.api.Assertions.assertTrue;
/** /**
* Tests for abstract factory. * Test for abstract factory.
*/ */
class AbstractFactoryTest { class AbstractFactoryTest {
private final App app = new App(); private final App app = new App();
@Test @Test
void verifyKingCreation() { void king() {
app.createKingdom(Kingdom.FactoryMaker.KingdomType.ELF); app.createKingdom(Kingdom.FactoryMaker.KingdomType.ELF);
final var kingdom = app.getKingdom(); final var kingdom = app.getKingdom();
@ -51,7 +51,7 @@ class AbstractFactoryTest {
} }
@Test @Test
void verifyCastleCreation() { void castle() {
app.createKingdom(Kingdom.FactoryMaker.KingdomType.ELF); app.createKingdom(Kingdom.FactoryMaker.KingdomType.ELF);
final var kingdom = app.getKingdom(); final var kingdom = app.getKingdom();
@ -66,7 +66,7 @@ class AbstractFactoryTest {
} }
@Test @Test
void verifyArmyCreation() { void army() {
app.createKingdom(Kingdom.FactoryMaker.KingdomType.ELF); app.createKingdom(Kingdom.FactoryMaker.KingdomType.ELF);
final var kingdom = app.getKingdom(); final var kingdom = app.getKingdom();
@ -81,7 +81,7 @@ class AbstractFactoryTest {
} }
@Test @Test
void verifyElfKingdomCreation() { void createElfKingdom() {
app.createKingdom(Kingdom.FactoryMaker.KingdomType.ELF); app.createKingdom(Kingdom.FactoryMaker.KingdomType.ELF);
final var kingdom = app.getKingdom(); final var kingdom = app.getKingdom();
@ -97,7 +97,7 @@ class AbstractFactoryTest {
} }
@Test @Test
void verifyOrcKingdomCreation() { void createOrcKingdom() {
app.createKingdom(Kingdom.FactoryMaker.KingdomType.ORC); app.createKingdom(Kingdom.FactoryMaker.KingdomType.ORC);
final var kingdom = app.getKingdom(); final var kingdom = app.getKingdom();

View File

@ -28,7 +28,10 @@ import org.junit.jupiter.api.Test;
import static org.junit.jupiter.api.Assertions.assertDoesNotThrow; import static org.junit.jupiter.api.Assertions.assertDoesNotThrow;
/** /**
* Check whether the execution of the main method in {@link App} throws an exception. * Issue: Add at least one assertion to this test case.
*
* Solution: Inserted assertion to check whether the execution of the main method in {@link App}
* throws an exception.
*/ */
class AppTest { class AppTest {

View File

@ -4,14 +4,13 @@ title: Active Object
folder: active-object folder: active-object
permalink: /patterns/active-object/ permalink: /patterns/active-object/
categories: Concurrency categories: Concurrency
language: en
tags: tags:
- Performance - Performance
--- ---
## Intent ## Intent
The active object design pattern decouples method execution from method invocation for objects that each reside in their thread of control. The goal is to introduce concurrency, by using asynchronous method invocation, and a scheduler for handling requests. The active object design pattern decouples method execution from method invocation for objects that each reside in their thread of control. The goal is to introduce concurrency, by using asynchronous method invocation and a scheduler for handling requests.
## Explanation ## Explanation
@ -70,7 +69,7 @@ public abstract class ActiveCreature{
requests.put(new Runnable() { requests.put(new Runnable() {
@Override @Override
public void run() { public void run() {
logger.info("{} has started to roam the wastelands.",name()); logger.info("{} has started to roam and the wastelands.",name());
} }
} }
); );
@ -82,7 +81,7 @@ public abstract class ActiveCreature{
} }
``` ```
We can see that any class that will extend the ActiveCreature class will have its own thread of control to invoke and execute methods. We can see that any class that will extend the ActiveCreature class will have its own thread of control to execute and invocate methods.
For example, the Orc class: For example, the Orc class:
@ -96,7 +95,7 @@ public class Orc extends ActiveCreature {
} }
``` ```
Now, we can create multiple creatures such as Orcs, tell them to eat and roam, and they will execute it on their own thread of control: Now, we can create multiple creatures such as Orcs, tell them to eat and roam and they will execute it on their own thread of control:
```java ```java
public static void main(String[] args) { public static void main(String[] args) {
@ -123,8 +122,4 @@ Now, we can create multiple creatures such as Orcs, tell them to eat and roam, a
## Class diagram ## Class diagram
![alt text](./etc/active-object.urm.png "Active Object class diagram") ![alt text](./etc/active-object.urm.PNG "Active Object class diagram")
## Tutorials
* [Android and Java Concurrency: The Active Object Pattern](https://www.youtube.com/watch?v=Cd8t2u5Qmvc)

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After

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@ -1,4 +1,4 @@
<?xml version="1.0" encoding="UTF-8"?> <?xml version="1.0"?>
<!-- <!--
The MIT License The MIT License
@ -23,40 +23,43 @@
THE SOFTWARE. THE SOFTWARE.
--> -->
<project xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd"> <project
<modelVersion>4.0.0</modelVersion> xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd"
<parent> xmlns="http://maven.apache.org/POM/4.0.0"
<groupId>com.iluwatar</groupId> xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance">
<artifactId>java-design-patterns</artifactId> <modelVersion>4.0.0</modelVersion>
<version>1.26.0-SNAPSHOT</version> <parent>
</parent> <groupId>com.iluwatar</groupId>
<artifactId>active-object</artifactId> <artifactId>java-design-patterns</artifactId>
<dependencies> <version>1.24.0-SNAPSHOT</version>
<dependency> </parent>
<groupId>org.junit.jupiter</groupId> <artifactId>active-object</artifactId>
<artifactId>junit-jupiter-engine</artifactId> <dependencies>
<scope>test</scope> <dependency>
</dependency> <groupId>org.junit.jupiter</groupId>
</dependencies> <artifactId>junit-jupiter-engine</artifactId>
<build> <scope>test</scope>
<plugins> </dependency>
<!-- Maven assembly plugin is invoked with default setting which we have </dependencies>
<build>
<plugins>
<!-- Maven assembly plugin is invoked with default setting which we have
in parent pom and specifying the class having main method --> in parent pom and specifying the class having main method -->
<plugin> <plugin>
<groupId>org.apache.maven.plugins</groupId> <groupId>org.apache.maven.plugins</groupId>
<artifactId>maven-assembly-plugin</artifactId> <artifactId>maven-assembly-plugin</artifactId>
<executions> <executions>
<execution> <execution>
<configuration> <configuration>
<archive> <archive>
<manifest> <manifest>
<mainClass>com.iluwatar.activeobject.App</mainClass> <mainClass>com.iluwatar.activeobject.App</mainClass>
</manifest> </manifest>
</archive> </archive>
</configuration> </configuration>
</execution> </execution>
</executions> </executions>
</plugin> </plugin>
</plugins> </plugins>
</build> </build>
</project> </project>

View File

@ -82,7 +82,7 @@ public abstract class ActiveCreature {
} }
/** /**
* Roam the wastelands. * Roam in the wastelands.
* @throws InterruptedException due to firing a new Runnable. * @throws InterruptedException due to firing a new Runnable.
*/ */
public void roam() throws InterruptedException { public void roam() throws InterruptedException {

View File

@ -4,7 +4,6 @@ title: Acyclic Visitor
folder: acyclic-visitor folder: acyclic-visitor
permalink: /patterns/acyclic-visitor/ permalink: /patterns/acyclic-visitor/
categories: Behavioral categories: Behavioral
language: en
tags: tags:
- Extensibility - Extensibility
--- ---
@ -138,10 +137,6 @@ This pattern can be used:
* When the visited class hierarchy will be frequently extended with new derivatives of the Element class. * When the visited class hierarchy will be frequently extended with new derivatives of the Element class.
* When the recompilation, relinking, retesting or redistribution of the derivatives of Element is very expensive. * When the recompilation, relinking, retesting or redistribution of the derivatives of Element is very expensive.
## Tutorial
* [Acyclic Visitor Pattern Example](https://codecrafter.blogspot.com/2012/12/the-acyclic-visitor-pattern.html)
## Consequences ## Consequences
The good: The good:

View File

@ -1,4 +1,3 @@
<?xml version="1.0" encoding="UTF-8"?>
<!-- <!--
The MIT License The MIT License
@ -23,47 +22,53 @@
THE SOFTWARE. THE SOFTWARE.
--> -->
<project xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd"> <project xmlns="http://maven.apache.org/POM/4.0.0"
<modelVersion>4.0.0</modelVersion> xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
<parent> xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
<groupId>com.iluwatar</groupId> <modelVersion>4.0.0</modelVersion>
<artifactId>java-design-patterns</artifactId>
<version>1.26.0-SNAPSHOT</version> <parent>
</parent> <groupId>com.iluwatar</groupId>
<artifactId>acyclic-visitor</artifactId> <artifactId>java-design-patterns</artifactId>
<properties> <version>1.24.0-SNAPSHOT</version>
<project.build.sourceEncoding>UTF-8</project.build.sourceEncoding> </parent>
<maven.compiler.source>1.8</maven.compiler.source>
<maven.compiler.target>1.8</maven.compiler.target> <artifactId>acyclic-visitor</artifactId>
</properties>
<dependencies> <properties>
<!-- https://mvnrepository.com/artifact/org.assertj/assertj-core --> <project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
<dependency> <maven.compiler.source>1.8</maven.compiler.source>
<groupId>org.assertj</groupId> <maven.compiler.target>1.8</maven.compiler.target>
<artifactId>assertj-core</artifactId> </properties>
<version>3.9.1</version>
<scope>test</scope> <dependencies>
</dependency> <!-- https://mvnrepository.com/artifact/org.assertj/assertj-core -->
<!-- https://mvnrepository.com/artifact/uk.org.lidalia/slf4j-test --> <dependency>
<dependency> <groupId>org.assertj</groupId>
<groupId>uk.org.lidalia</groupId> <artifactId>assertj-core</artifactId>
<artifactId>slf4j-test</artifactId> <version>3.9.1</version>
<version>1.2.0</version> <scope>test</scope>
<scope>test</scope> </dependency>
</dependency> <!-- https://mvnrepository.com/artifact/uk.org.lidalia/slf4j-test -->
<dependency> <dependency>
<groupId>org.junit.jupiter</groupId> <groupId>uk.org.lidalia</groupId>
<artifactId>junit-jupiter-engine</artifactId> <artifactId>slf4j-test</artifactId>
<scope>test</scope> <version>1.2.0</version>
</dependency> <scope>test</scope>
<dependency> </dependency>
<groupId>org.mockito</groupId> <dependency>
<artifactId>mockito-all</artifactId> <groupId>org.junit.jupiter</groupId>
<version>1.10.19</version> <artifactId>junit-jupiter-engine</artifactId>
<scope>test</scope> <scope>test</scope>
</dependency> </dependency>
</dependencies> <dependency>
<build> <groupId>org.mockito</groupId>
<artifactId>mockito-all</artifactId>
<version>1.10.19</version>
<scope>test</scope>
</dependency>
</dependencies>
<build>
<plugins> <plugins>
<!-- Maven assembly plugin is invoked with default setting which we have <!-- Maven assembly plugin is invoked with default setting which we have
in parent pom and specifying the class having main method --> in parent pom and specifying the class having main method -->

View File

@ -29,7 +29,7 @@ import lombok.extern.slf4j.Slf4j;
* Hayes class implements its accept method. * Hayes class implements its accept method.
*/ */
@Slf4j @Slf4j
public class Hayes implements Modem { public class Hayes extends Modem {
/** /**
* Accepts all visitors but honors only HayesVisitor. * Accepts all visitors but honors only HayesVisitor.

View File

@ -24,9 +24,8 @@
package com.iluwatar.acyclicvisitor; package com.iluwatar.acyclicvisitor;
/** /**
* //Modem abstract class. * Modem abstract class.
* converted to an interface
*/ */
public interface Modem { public abstract class Modem {
void accept(ModemVisitor modemVisitor); public abstract void accept(ModemVisitor modemVisitor);
} }

View File

@ -29,7 +29,7 @@ import lombok.extern.slf4j.Slf4j;
* Zoom class implements its accept method. * Zoom class implements its accept method.
*/ */
@Slf4j @Slf4j
public class Zoom implements Modem { public class Zoom extends Modem {
/** /**
* Accepts all visitors but honors only ZoomVisitor. * Accepts all visitors but honors only ZoomVisitor.

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@ -4,7 +4,6 @@ title: Adapter
folder: adapter folder: adapter
permalink: /patterns/adapter/ permalink: /patterns/adapter/
categories: Structural categories: Structural
language: en
tags: tags:
- Gang of Four - Gang of Four
--- ---
@ -18,10 +17,10 @@ couldn't otherwise because of incompatible interfaces.
## Explanation ## Explanation
Real-world example Real world example
> Consider that you have some pictures on your memory card and you need to transfer them to your computer. To transfer them, you need some kind of adapter that is compatible with your computer ports so that you can attach a memory card to your computer. In this case card reader is an adapter. > Consider that you have some pictures in your memory card and you need to transfer them to your computer. In order to transfer them you need some kind of adapter that is compatible with your computer ports so that you can attach memory card to your computer. In this case card reader is an adapter.
> Another example would be the famous power adapter; a three-legged plug can't be connected to a two-pronged outlet, it needs to use a power adapter that makes it compatible with the two-pronged outlets. > Another example would be the famous power adapter; a three legged plug can't be connected to a two pronged outlet, it needs to use a power adapter that makes it compatible with the two pronged outlet.
> Yet another example would be a translator translating words spoken by one person to another > Yet another example would be a translator translating words spoken by one person to another
In plain words In plain words
@ -36,7 +35,7 @@ Wikipedia says
Consider a captain that can only use rowing boats and cannot sail at all. Consider a captain that can only use rowing boats and cannot sail at all.
First, we have interfaces `RowingBoat` and `FishingBoat` First we have interfaces `RowingBoat` and `FishingBoat`
```java ```java
public interface RowingBoat { public interface RowingBoat {
@ -68,7 +67,7 @@ public class Captain {
} }
``` ```
Now let's say the pirates are coming and our captain needs to escape but there is only a fishing boat available. We need to create an adapter that allows the captain to operate the fishing boat with his rowing boat skills. Now let's say the pirates are coming and our captain needs to escape but there is only fishing boat available. We need to create an adapter that allows the captain to operate the fishing boat with his rowing boat skills.
```java ```java
@Slf4j @Slf4j
@ -100,31 +99,25 @@ captain.row();
## Applicability ## Applicability
Use the Adapter pattern when Use the Adapter pattern when
* You want to use an existing class, and its interface does not match the one you need * you want to use an existing class, and its interface does not match the one you need
* You want to create a reusable class that cooperates with unrelated or unforeseen classes, that is, classes that don't necessarily have compatible interfaces * you want to create a reusable class that cooperates with unrelated or unforeseen classes, that is, classes that don't necessarily have compatible interfaces
* You need to use several existing subclasses, but it's impractical to adapt their interface by subclassing everyone. An object adapter can adapt the interface of its parent class. * you need to use several existing subclasses, but it's impractical to adapt their interface by subclassing every one. An object adapter can adapt the interface of its parent class.
* Most of the applications using third-party libraries use adapters as a middle layer between the application and the 3rd party library to decouple the application from the library. If another library has to be used only an adapter for the new library is required without having to change the application code. * most of the applications using third party libraries use adapters as a middle layer between the application and the 3rd party library to decouple the application from the library. If another library has to be used only an adapter for the new library is required without having to change the application code.
## Tutorials ## Consequences:
* [Dzone](https://dzone.com/articles/adapter-design-pattern-in-java)
* [Refactoring Guru](https://refactoring.guru/design-patterns/adapter/java/example)
* [Baeldung](https://www.baeldung.com/java-adapter-pattern)
## Consequences
Class and object adapters have different trade-offs. A class adapter Class and object adapters have different trade-offs. A class adapter
* Adapts Adaptee to Target by committing to a concrete Adaptee class. As a consequence, a class adapter wont work when we want to adapt a class and all its subclasses. * adapts Adaptee to Target by committing to a concrete Adaptee class. As a consequence, a class adapter wont work when we want to adapt a class and all its subclasses.
* Lets Adapter override some of Adaptees behavior since Adapter is a subclass of Adaptee. * lets Adapter override some of Adaptees behavior, since Adapter is a subclass of Adaptee.
* Introduces only one object, and no additional pointer indirection is needed to get to the adaptee. * introduces only one object, and no additional pointer indirection is needed to get to the adaptee.
An object adapter An object adapter
* Lets a single Adapter work with many Adaptees—that is, the Adaptee itself and all of its subclasses (if any). The Adapter can also add functionality to all Adaptees at once. * lets a single Adapter work with many Adaptees—that is, the Adaptee itself and all of its subclasses (if any). The Adapter can also add functionality to all Adaptees at once.
* Makes it harder to override Adaptee behavior. It will require subclassing Adaptee and making the Adapter refer to the subclass rather than the Adaptee itself. * makes it harder to override Adaptee behavior. It will require subclassing Adaptee and making Adapter refer to the subclass rather than the Adaptee itself.
## Real-world examples ## Real world examples
* [java.util.Arrays#asList()](http://docs.oracle.com/javase/8/docs/api/java/util/Arrays.html#asList%28T...%29) * [java.util.Arrays#asList()](http://docs.oracle.com/javase/8/docs/api/java/util/Arrays.html#asList%28T...%29)
* [java.util.Collections#list()](https://docs.oracle.com/javase/8/docs/api/java/util/Collections.html#list-java.util.Enumeration-) * [java.util.Collections#list()](https://docs.oracle.com/javase/8/docs/api/java/util/Collections.html#list-java.util.Enumeration-)

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@ -1,4 +1,4 @@
<?xml version="1.0" encoding="UTF-8"?> <?xml version="1.0"?>
<!-- <!--
The MIT License The MIT License
@ -23,45 +23,48 @@
THE SOFTWARE. THE SOFTWARE.
--> -->
<project xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd"> <project
<modelVersion>4.0.0</modelVersion> xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd"
<parent> xmlns="http://maven.apache.org/POM/4.0.0"
<groupId>com.iluwatar</groupId> xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance">
<artifactId>java-design-patterns</artifactId> <modelVersion>4.0.0</modelVersion>
<version>1.26.0-SNAPSHOT</version> <parent>
</parent> <groupId>com.iluwatar</groupId>
<artifactId>adapter</artifactId> <artifactId>java-design-patterns</artifactId>
<dependencies> <version>1.24.0-SNAPSHOT</version>
<dependency> </parent>
<groupId>org.junit.jupiter</groupId> <artifactId>adapter</artifactId>
<artifactId>junit-jupiter-engine</artifactId> <dependencies>
<scope>test</scope> <dependency>
</dependency> <groupId>org.junit.jupiter</groupId>
<dependency> <artifactId>junit-jupiter-engine</artifactId>
<groupId>org.mockito</groupId> <scope>test</scope>
<artifactId>mockito-core</artifactId> </dependency>
<scope>test</scope> <dependency>
</dependency> <groupId>org.mockito</groupId>
</dependencies> <artifactId>mockito-core</artifactId>
<build> <scope>test</scope>
<plugins> </dependency>
<!-- Maven assembly plugin is invoked with default setting which we have </dependencies>
<build>
<plugins>
<!-- Maven assembly plugin is invoked with default setting which we have
in parent pom and specifying the class having main method --> in parent pom and specifying the class having main method -->
<plugin> <plugin>
<groupId>org.apache.maven.plugins</groupId> <groupId>org.apache.maven.plugins</groupId>
<artifactId>maven-assembly-plugin</artifactId> <artifactId>maven-assembly-plugin</artifactId>
<executions> <executions>
<execution> <execution>
<configuration> <configuration>
<archive> <archive>
<manifest> <manifest>
<mainClass>com.iluwatar.adapter.App</mainClass> <mainClass>com.iluwatar.adapter.App</mainClass>
</manifest> </manifest>
</archive> </archive>
</configuration> </configuration>
</execution> </execution>
</executions> </executions>
</plugin> </plugin>
</plugins> </plugins>
</build> </build>
</project> </project>

View File

@ -33,7 +33,7 @@ import static org.mockito.Mockito.spy;
import static org.mockito.Mockito.verify; import static org.mockito.Mockito.verify;
/** /**
* Tests for the adapter pattern. * Test class
*/ */
class AdapterPatternTest { class AdapterPatternTest {

View File

@ -33,7 +33,9 @@ import static org.junit.jupiter.api.Assertions.assertDoesNotThrow;
class AppTest { class AppTest {
/** /**
* Check whether the execution of the main method in {@link App} * Issue: Add at least one assertion to this test case.
*
* Solution: Inserted assertion to check whether the execution of the main method in {@link App}
* throws an exception. * throws an exception.
*/ */

View File

@ -4,7 +4,6 @@ title: Aggregator Microservices
folder: aggregator-microservices folder: aggregator-microservices
permalink: /patterns/aggregator-microservices/ permalink: /patterns/aggregator-microservices/
categories: Architectural categories: Architectural
language: en
tags: tags:
- Cloud distributed - Cloud distributed
- Decoupling - Decoupling

View File

@ -23,65 +23,68 @@
THE SOFTWARE. THE SOFTWARE.
--> -->
<project xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd"> <project xmlns="http://maven.apache.org/POM/4.0.0"
<parent> xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
<artifactId>aggregator-microservices</artifactId> xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
<groupId>com.iluwatar</groupId> <parent>
<version>1.26.0-SNAPSHOT</version> <artifactId>aggregator-microservices</artifactId>
</parent> <groupId>com.iluwatar</groupId>
<modelVersion>4.0.0</modelVersion> <version>1.24.0-SNAPSHOT</version>
<artifactId>aggregator-service</artifactId> </parent>
<packaging>jar</packaging> <modelVersion>4.0.0</modelVersion>
<dependencies> <artifactId>aggregator-service</artifactId>
<dependency> <packaging>jar</packaging>
<groupId>org.springframework</groupId> <dependencies>
<artifactId>spring-webmvc</artifactId> <dependency>
</dependency> <groupId>org.springframework</groupId>
<dependency> <artifactId>spring-webmvc</artifactId>
<groupId>org.springframework.boot</groupId> </dependency>
<artifactId>spring-boot-starter-web</artifactId> <dependency>
</dependency> <groupId>org.springframework.boot</groupId>
<dependency> <artifactId>spring-boot-starter-web</artifactId>
<groupId>org.junit.jupiter</groupId> </dependency>
<artifactId>junit-jupiter-engine</artifactId> <dependency>
<scope>test</scope> <groupId>org.junit.jupiter</groupId>
</dependency> <artifactId>junit-jupiter-engine</artifactId>
<dependency> <scope>test</scope>
<groupId>org.mockito</groupId> </dependency>
<artifactId>mockito-core</artifactId> <dependency>
<scope>test</scope> <groupId>org.mockito</groupId>
</dependency> <artifactId>mockito-core</artifactId>
</dependencies> <scope>test</scope>
<build> </dependency>
<plugins> </dependencies>
<plugin>
<groupId>org.springframework.boot</groupId> <build>
<artifactId>spring-boot-maven-plugin</artifactId> <plugins>
<executions> <plugin>
<execution> <groupId>org.springframework.boot</groupId>
<goals> <artifactId>spring-boot-maven-plugin</artifactId>
<goal>repackage</goal> <executions>
</goals> <execution>
</execution> <goals>
</executions> <goal>repackage</goal>
</plugin> </goals>
<!-- Maven assembly plugin is invoked with default setting which we have </execution>
</executions>
</plugin>
<!-- Maven assembly plugin is invoked with default setting which we have
in parent pom and specifying the class having main method --> in parent pom and specifying the class having main method -->
<plugin> <plugin>
<groupId>org.apache.maven.plugins</groupId> <groupId>org.apache.maven.plugins</groupId>
<artifactId>maven-assembly-plugin</artifactId> <artifactId>maven-assembly-plugin</artifactId>
<executions> <executions>
<execution> <execution>
<configuration> <configuration>
<archive> <archive>
<manifest> <manifest>
<mainClass>com.iluwatar.aggregator.microservices.App</mainClass> <mainClass>com.iluwatar.aggregator.microservices.App</mainClass>
</manifest> </manifest>
</archive> </archive>
</configuration> </configuration>
</execution> </execution>
</executions> </executions>
</plugin> </plugin>
</plugins> </plugins>
</build> </build>
</project> </project>

View File

@ -48,7 +48,7 @@ class AggregatorTest {
@BeforeEach @BeforeEach
public void setup() { public void setup() {
MockitoAnnotations.openMocks(this); MockitoAnnotations.initMocks(this);
} }
/** /**

View File

@ -23,58 +23,63 @@
THE SOFTWARE. THE SOFTWARE.
--> -->
<project xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd"> <project xmlns="http://maven.apache.org/POM/4.0.0"
<parent> xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
<artifactId>aggregator-microservices</artifactId> xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
<groupId>com.iluwatar</groupId> <parent>
<version>1.26.0-SNAPSHOT</version> <artifactId>aggregator-microservices</artifactId>
</parent> <groupId>com.iluwatar</groupId>
<modelVersion>4.0.0</modelVersion> <version>1.24.0-SNAPSHOT</version>
<artifactId>information-microservice</artifactId> </parent>
<packaging>jar</packaging> <modelVersion>4.0.0</modelVersion>
<dependencies>
<dependency> <artifactId>information-microservice</artifactId>
<groupId>org.springframework</groupId> <packaging>jar</packaging>
<artifactId>spring-webmvc</artifactId>
</dependency> <dependencies>
<dependency> <dependency>
<groupId>org.springframework.boot</groupId> <groupId>org.springframework</groupId>
<artifactId>spring-boot-starter-web</artifactId> <artifactId>spring-webmvc</artifactId>
</dependency> </dependency>
<dependency> <dependency>
<groupId>org.junit.jupiter</groupId> <groupId>org.springframework.boot</groupId>
<artifactId>junit-jupiter-engine</artifactId> <artifactId>spring-boot-starter-web</artifactId>
<scope>test</scope> </dependency>
</dependency> <dependency>
</dependencies> <groupId>org.junit.jupiter</groupId>
<build> <artifactId>junit-jupiter-engine</artifactId>
<plugins> <scope>test</scope>
<plugin> </dependency>
<groupId>org.springframework.boot</groupId> </dependencies>
<artifactId>spring-boot-maven-plugin</artifactId>
<executions> <build>
<execution> <plugins>
<goals> <plugin>
<goal>repackage</goal> <groupId>org.springframework.boot</groupId>
</goals> <artifactId>spring-boot-maven-plugin</artifactId>
</execution> <executions>
</executions> <execution>
</plugin> <goals>
<plugin> <goal>repackage</goal>
<groupId>org.apache.maven.plugins</groupId> </goals>
<artifactId>maven-assembly-plugin</artifactId> </execution>
<executions> </executions>
<execution> </plugin>
<configuration> <plugin>
<archive> <groupId>org.apache.maven.plugins</groupId>
<manifest> <artifactId>maven-assembly-plugin</artifactId>
<mainClass>com.iluwatar.information.microservices.InformationApplication</mainClass> <executions>
</manifest> <execution>
</archive> <configuration>
</configuration> <archive>
</execution> <manifest>
</executions> <mainClass>com.iluwatar.information.microservices.InformationApplication</mainClass>
</plugin> </manifest>
</plugins> </archive>
</build> </configuration>
</execution>
</executions>
</plugin>
</plugins>
</build>
</project> </project>

View File

@ -23,58 +23,62 @@
THE SOFTWARE. THE SOFTWARE.
--> -->
<project xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd"> <project xmlns="http://maven.apache.org/POM/4.0.0"
<parent> xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
<artifactId>aggregator-microservices</artifactId> xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
<groupId>com.iluwatar</groupId> <parent>
<version>1.26.0-SNAPSHOT</version> <artifactId>aggregator-microservices</artifactId>
</parent> <groupId>com.iluwatar</groupId>
<modelVersion>4.0.0</modelVersion> <version>1.24.0-SNAPSHOT</version>
<artifactId>inventory-microservice</artifactId> </parent>
<packaging>jar</packaging> <modelVersion>4.0.0</modelVersion>
<dependencies> <artifactId>inventory-microservice</artifactId>
<dependency>
<groupId>org.springframework</groupId> <packaging>jar</packaging>
<artifactId>spring-webmvc</artifactId> <dependencies>
</dependency> <dependency>
<dependency> <groupId>org.springframework</groupId>
<groupId>org.springframework.boot</groupId> <artifactId>spring-webmvc</artifactId>
<artifactId>spring-boot-starter-web</artifactId> </dependency>
</dependency> <dependency>
<dependency> <groupId>org.springframework.boot</groupId>
<groupId>org.junit.jupiter</groupId> <artifactId>spring-boot-starter-web</artifactId>
<artifactId>junit-jupiter-engine</artifactId> </dependency>
<scope>test</scope> <dependency>
</dependency> <groupId>org.junit.jupiter</groupId>
</dependencies> <artifactId>junit-jupiter-engine</artifactId>
<build> <scope>test</scope>
<plugins> </dependency>
<plugin> </dependencies>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-maven-plugin</artifactId> <build>
<executions> <plugins>
<execution> <plugin>
<goals> <groupId>org.springframework.boot</groupId>
<goal>repackage</goal> <artifactId>spring-boot-maven-plugin</artifactId>
</goals> <executions>
</execution> <execution>
</executions> <goals>
</plugin> <goal>repackage</goal>
<plugin> </goals>
<groupId>org.apache.maven.plugins</groupId> </execution>
<artifactId>maven-assembly-plugin</artifactId> </executions>
<executions> </plugin>
<execution> <plugin>
<configuration> <groupId>org.apache.maven.plugins</groupId>
<archive> <artifactId>maven-assembly-plugin</artifactId>
<manifest> <executions>
<mainClass>com.iluwatar.inventory.microservices.InventoryApplication</mainClass> <execution>
</manifest> <configuration>
</archive> <archive>
</configuration> <manifest>
</execution> <mainClass>com.iluwatar.inventory.microservices.InventoryApplication</mainClass>
</executions> </manifest>
</plugin> </archive>
</plugins> </configuration>
</build> </execution>
</executions>
</plugin>
</plugins>
</build>
</project> </project>

View File

@ -23,18 +23,20 @@
THE SOFTWARE. THE SOFTWARE.
--> -->
<project xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd"> <project xmlns="http://maven.apache.org/POM/4.0.0"
<parent> xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
<artifactId>java-design-patterns</artifactId> xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
<groupId>com.iluwatar</groupId> <parent>
<version>1.26.0-SNAPSHOT</version> <artifactId>java-design-patterns</artifactId>
</parent> <groupId>com.iluwatar</groupId>
<modelVersion>4.0.0</modelVersion> <version>1.24.0-SNAPSHOT</version>
<artifactId>aggregator-microservices</artifactId> </parent>
<packaging>pom</packaging> <modelVersion>4.0.0</modelVersion>
<modules> <artifactId>aggregator-microservices</artifactId>
<module>information-microservice</module> <packaging>pom</packaging>
<module>aggregator-service</module> <modules>
<module>inventory-microservice</module> <module>information-microservice</module>
</modules> <module>aggregator-service</module>
<module>inventory-microservice</module>
</modules>
</project> </project>

View File

@ -4,7 +4,6 @@ title: Ambassador
folder: ambassador folder: ambassador
permalink: /patterns/ambassador/ permalink: /patterns/ambassador/
categories: Structural categories: Structural
language: en
tags: tags:
- Decoupling - Decoupling
- Cloud distributed - Cloud distributed

View File

@ -23,38 +23,40 @@
THE SOFTWARE. THE SOFTWARE.
--> -->
<project xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd"> <project xmlns="http://maven.apache.org/POM/4.0.0"
<parent> xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
<artifactId>java-design-patterns</artifactId> xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
<groupId>com.iluwatar</groupId> <parent>
<version>1.26.0-SNAPSHOT</version> <artifactId>java-design-patterns</artifactId>
</parent> <groupId>com.iluwatar</groupId>
<modelVersion>4.0.0</modelVersion> <version>1.24.0-SNAPSHOT</version>
<artifactId>ambassador</artifactId> </parent>
<dependencies> <modelVersion>4.0.0</modelVersion>
<dependency> <artifactId>ambassador</artifactId>
<groupId>org.junit.jupiter</groupId> <dependencies>
<artifactId>junit-jupiter-engine</artifactId> <dependency>
<scope>test</scope> <groupId>org.junit.jupiter</groupId>
</dependency> <artifactId>junit-jupiter-engine</artifactId>
</dependencies> <scope>test</scope>
<build> </dependency>
<plugins> </dependencies>
<plugin> <build>
<groupId>org.apache.maven.plugins</groupId> <plugins>
<artifactId>maven-assembly-plugin</artifactId> <plugin>
<executions> <groupId>org.apache.maven.plugins</groupId>
<execution> <artifactId>maven-assembly-plugin</artifactId>
<configuration> <executions>
<archive> <execution>
<manifest> <configuration>
<mainClass>com.iluwatar.ambassador.App</mainClass> <archive>
</manifest> <manifest>
</archive> <mainClass>com.iluwatar.ambassador.App</mainClass>
</configuration> </manifest>
</execution> </archive>
</executions> </configuration>
</plugin> </execution>
</plugins> </executions>
</build> </plugin>
</plugins>
</build>
</project> </project>

View File

@ -4,7 +4,6 @@ title: API Gateway
folder: api-gateway folder: api-gateway
permalink: /patterns/api-gateway/ permalink: /patterns/api-gateway/
categories: Architectural categories: Architectural
language: en
tags: tags:
- Cloud distributed - Cloud distributed
- Decoupling - Decoupling

View File

@ -23,11 +23,13 @@
THE SOFTWARE. THE SOFTWARE.
--> -->
<project xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd"> <project xmlns="http://maven.apache.org/POM/4.0.0"
xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
<parent> <parent>
<artifactId>api-gateway</artifactId> <artifactId>api-gateway</artifactId>
<groupId>com.iluwatar</groupId> <groupId>com.iluwatar</groupId>
<version>1.26.0-SNAPSHOT</version> <version>1.24.0-SNAPSHOT</version>
</parent> </parent>
<modelVersion>4.0.0</modelVersion> <modelVersion>4.0.0</modelVersion>
<artifactId>api-gateway-service</artifactId> <artifactId>api-gateway-service</artifactId>
@ -52,6 +54,7 @@
<scope>test</scope> <scope>test</scope>
</dependency> </dependency>
</dependencies> </dependencies>
<build> <build>
<plugins> <plugins>
<plugin> <plugin>

View File

@ -48,7 +48,7 @@ class ApiGatewayTest {
@BeforeEach @BeforeEach
public void setup() { public void setup() {
MockitoAnnotations.openMocks(this); MockitoAnnotations.initMocks(this);
} }
/** /**

View File

@ -23,11 +23,13 @@
THE SOFTWARE. THE SOFTWARE.
--> -->
<project xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd"> <project xmlns="http://maven.apache.org/POM/4.0.0"
xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
<parent> <parent>
<artifactId>api-gateway</artifactId> <artifactId>api-gateway</artifactId>
<groupId>com.iluwatar</groupId> <groupId>com.iluwatar</groupId>
<version>1.26.0-SNAPSHOT</version> <version>1.24.0-SNAPSHOT</version>
</parent> </parent>
<modelVersion>4.0.0</modelVersion> <modelVersion>4.0.0</modelVersion>
<artifactId>image-microservice</artifactId> <artifactId>image-microservice</artifactId>
@ -47,6 +49,7 @@
<scope>test</scope> <scope>test</scope>
</dependency> </dependency>
</dependencies> </dependencies>
<build> <build>
<plugins> <plugins>
<plugin> <plugin>

View File

@ -23,11 +23,13 @@
THE SOFTWARE. THE SOFTWARE.
--> -->
<project xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd"> <project xmlns="http://maven.apache.org/POM/4.0.0"
xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
<parent> <parent>
<artifactId>java-design-patterns</artifactId> <artifactId>java-design-patterns</artifactId>
<groupId>com.iluwatar</groupId> <groupId>com.iluwatar</groupId>
<version>1.26.0-SNAPSHOT</version> <version>1.24.0-SNAPSHOT</version>
</parent> </parent>
<modelVersion>4.0.0</modelVersion> <modelVersion>4.0.0</modelVersion>
<artifactId>api-gateway</artifactId> <artifactId>api-gateway</artifactId>

View File

@ -23,15 +23,19 @@
THE SOFTWARE. THE SOFTWARE.
--> -->
<project xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd"> <project xmlns="http://maven.apache.org/POM/4.0.0"
xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
<parent> <parent>
<artifactId>api-gateway</artifactId> <artifactId>api-gateway</artifactId>
<groupId>com.iluwatar</groupId> <groupId>com.iluwatar</groupId>
<version>1.26.0-SNAPSHOT</version> <version>1.24.0-SNAPSHOT</version>
</parent> </parent>
<modelVersion>4.0.0</modelVersion> <modelVersion>4.0.0</modelVersion>
<artifactId>price-microservice</artifactId> <artifactId>price-microservice</artifactId>
<packaging>jar</packaging> <packaging>jar</packaging>
<dependencies> <dependencies>
<dependency> <dependency>
<groupId>org.springframework</groupId> <groupId>org.springframework</groupId>
@ -47,6 +51,7 @@
<scope>test</scope> <scope>test</scope>
</dependency> </dependency>
</dependencies> </dependencies>
<build> <build>
<plugins> <plugins>
<plugin> <plugin>

View File

@ -4,7 +4,6 @@ title: Arrange/Act/Assert
folder: arrange-act-assert folder: arrange-act-assert
permalink: /patterns/arrange-act-assert/ permalink: /patterns/arrange-act-assert/
categories: Idiom categories: Idiom
language: en
tags: tags:
- Testing - Testing
--- ---

View File

@ -23,13 +23,16 @@
THE SOFTWARE. THE SOFTWARE.
--> -->
<project xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd"> <project xmlns="http://maven.apache.org/POM/4.0.0"
xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
<parent> <parent>
<artifactId>java-design-patterns</artifactId> <artifactId>java-design-patterns</artifactId>
<groupId>com.iluwatar</groupId> <groupId>com.iluwatar</groupId>
<version>1.26.0-SNAPSHOT</version> <version>1.24.0-SNAPSHOT</version>
</parent> </parent>
<modelVersion>4.0.0</modelVersion> <modelVersion>4.0.0</modelVersion>
<artifactId>arrange-act-assert</artifactId> <artifactId>arrange-act-assert</artifactId>
<dependencies> <dependencies>
<dependency> <dependency>
@ -38,4 +41,4 @@
<scope>test</scope> <scope>test</scope>
</dependency> </dependency>
</dependencies> </dependencies>
</project> </project>

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@ -4,7 +4,6 @@ title: Async Method Invocation
folder: async-method-invocation folder: async-method-invocation
permalink: /patterns/async-method-invocation/ permalink: /patterns/async-method-invocation/
categories: Concurrency categories: Concurrency
language: en
tags: tags:
- Reactive - Reactive
--- ---

View File

@ -1,4 +1,4 @@
<?xml version="1.0" encoding="UTF-8"?> <?xml version="1.0"?>
<!-- <!--
The MIT License The MIT License
@ -23,43 +23,46 @@
THE SOFTWARE. THE SOFTWARE.
--> -->
<project xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd"> <project
<modelVersion>4.0.0</modelVersion> xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd"
<parent> xmlns="http://maven.apache.org/POM/4.0.0"
<groupId>com.iluwatar</groupId> xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance">
<artifactId>java-design-patterns</artifactId> <modelVersion>4.0.0</modelVersion>
<version>1.26.0-SNAPSHOT</version> <parent>
</parent> <groupId>com.iluwatar</groupId>
<artifactId>async-method-invocation</artifactId> <artifactId>java-design-patterns</artifactId>
<dependencies> <version>1.24.0-SNAPSHOT</version>
<dependency> </parent>
<groupId>org.junit.jupiter</groupId> <artifactId>async-method-invocation</artifactId>
<artifactId>junit-jupiter-engine</artifactId> <dependencies>
<scope>test</scope> <dependency>
</dependency> <groupId>org.junit.jupiter</groupId>
<dependency> <artifactId>junit-jupiter-engine</artifactId>
<groupId>org.mockito</groupId> <scope>test</scope>
<artifactId>mockito-core</artifactId> </dependency>
<scope>test</scope> <dependency>
</dependency> <groupId>org.mockito</groupId>
</dependencies> <artifactId>mockito-core</artifactId>
<build> <scope>test</scope>
<plugins> </dependency>
<plugin> </dependencies>
<groupId>org.apache.maven.plugins</groupId> <build>
<artifactId>maven-assembly-plugin</artifactId> <plugins>
<executions> <plugin>
<execution> <groupId>org.apache.maven.plugins</groupId>
<configuration> <artifactId>maven-assembly-plugin</artifactId>
<archive> <executions>
<manifest> <execution>
<mainClass>com.iluwatar.async.method.invocation.App</mainClass> <configuration>
</manifest> <archive>
</archive> <manifest>
</configuration> <mainClass>com.iluwatar.async.method.invocation.App</mainClass>
</execution> </manifest>
</executions> </archive>
</plugin> </configuration>
</plugins> </execution>
</build> </executions>
</plugin>
</plugins>
</build>
</project> </project>

View File

@ -59,12 +59,9 @@ import lombok.extern.slf4j.Slf4j;
@Slf4j @Slf4j
public class App { public class App {
private static final String ROCKET_LAUNCH_LOG_PATTERN = "Space rocket <%s> launched successfully";
/** /**
* Program entry point. * Program entry point.
*/ */
public static void main(String[] args) throws Exception { public static void main(String[] args) throws Exception {
// construct a new executor that will run async tasks // construct a new executor that will run async tasks
var executor = new ThreadAsyncExecutor(); var executor = new ThreadAsyncExecutor();
@ -90,9 +87,9 @@ public class App {
asyncResult5.await(); asyncResult5.await();
// log the results of the tasks, callbacks log immediately when complete // log the results of the tasks, callbacks log immediately when complete
log(String.format(ROCKET_LAUNCH_LOG_PATTERN, result1)); log("Space rocket <" + result1 + "> launch complete");
log(String.format(ROCKET_LAUNCH_LOG_PATTERN, result2)); log("Space rocket <" + result2 + "> launch complete");
log(String.format(ROCKET_LAUNCH_LOG_PATTERN, result3)); log("Space rocket <" + result3 + "> launch complete");
} }
/** /**
@ -105,7 +102,7 @@ public class App {
private static <T> Callable<T> lazyval(T value, long delayMillis) { private static <T> Callable<T> lazyval(T value, long delayMillis) {
return () -> { return () -> {
Thread.sleep(delayMillis); Thread.sleep(delayMillis);
log(String.format(ROCKET_LAUNCH_LOG_PATTERN, value)); log("Space rocket <" + value + "> launched successfully");
return value; return value;
}; };
} }

View File

@ -68,7 +68,7 @@ class ThreadAsyncExecutorTest {
@BeforeEach @BeforeEach
void setUp() { void setUp() {
MockitoAnnotations.openMocks(this); MockitoAnnotations.initMocks(this);
} }
/** /**

View File

@ -4,7 +4,6 @@ title: Balking
folder: balking folder: balking
permalink: /patterns/balking/ permalink: /patterns/balking/
categories: Concurrency categories: Concurrency
language: en
tags: tags:
- Decoupling - Decoupling
--- ---

View File

@ -23,38 +23,41 @@
THE SOFTWARE. THE SOFTWARE.
--> -->
<project xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd"> <project xmlns="http://maven.apache.org/POM/4.0.0"
<parent> xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
<artifactId>java-design-patterns</artifactId> xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
<groupId>com.iluwatar</groupId> <parent>
<version>1.26.0-SNAPSHOT</version> <artifactId>java-design-patterns</artifactId>
</parent> <groupId>com.iluwatar</groupId>
<modelVersion>4.0.0</modelVersion> <version>1.24.0-SNAPSHOT</version>
<artifactId>balking</artifactId> </parent>
<dependencies> <modelVersion>4.0.0</modelVersion>
<dependency>
<groupId>org.junit.jupiter</groupId> <artifactId>balking</artifactId>
<artifactId>junit-jupiter-engine</artifactId> <dependencies>
<scope>test</scope> <dependency>
</dependency> <groupId>org.junit.jupiter</groupId>
</dependencies> <artifactId>junit-jupiter-engine</artifactId>
<build> <scope>test</scope>
<plugins> </dependency>
<plugin> </dependencies>
<groupId>org.apache.maven.plugins</groupId> <build>
<artifactId>maven-assembly-plugin</artifactId> <plugins>
<executions> <plugin>
<execution> <groupId>org.apache.maven.plugins</groupId>
<configuration> <artifactId>maven-assembly-plugin</artifactId>
<archive> <executions>
<manifest> <execution>
<mainClass>com.iluwatar.balking.App</mainClass> <configuration>
</manifest> <archive>
</archive> <manifest>
</configuration> <mainClass>com.iluwatar.balking.App</mainClass>
</execution> </manifest>
</executions> </archive>
</plugin> </configuration>
</plugins> </execution>
</build> </executions>
</plugin>
</plugins>
</build>
</project> </project>

View File

@ -4,7 +4,6 @@ title: Bridge
folder: bridge folder: bridge
permalink: /patterns/bridge/ permalink: /patterns/bridge/
categories: Structural categories: Structural
language: en
tags: tags:
- Gang of Four - Gang of Four
--- ---
@ -19,7 +18,7 @@ Decouple an abstraction from its implementation so that the two can vary indepen
## Explanation ## Explanation
Real-world example Real world example
> Consider you have a weapon with different enchantments, and you are supposed to allow mixing > Consider you have a weapon with different enchantments, and you are supposed to allow mixing
> different weapons with different enchantments. What would you do? Create multiple copies of each > different weapons with different enchantments. What would you do? Create multiple copies of each
@ -161,36 +160,27 @@ public class SoulEatingEnchantment implements Enchantment {
Here are both hierarchies in action: Here are both hierarchies in action:
```java ```java
LOGGER.info("The knight receives an enchanted sword.");
var enchantedSword = new Sword(new SoulEatingEnchantment()); var enchantedSword = new Sword(new SoulEatingEnchantment());
enchantedSword.wield(); enchantedSword.wield();
enchantedSword.swing(); enchantedSword.swing();
enchantedSword.unwield(); enchantedSword.unwield();
// The sword is wielded.
// The item spreads bloodlust.
// The sword is swinged.
// The item eats the soul of enemies.
// The sword is unwielded.
// Bloodlust slowly disappears.
LOGGER.info("The valkyrie receives an enchanted hammer.");
var hammer = new Hammer(new FlyingEnchantment()); var hammer = new Hammer(new FlyingEnchantment());
hammer.wield(); hammer.wield();
hammer.swing(); hammer.swing();
hammer.unwield(); hammer.unwield();
``` // The hammer is wielded.
// The item begins to glow faintly.
Here's the console output. // The hammer is swinged.
// The item flies and strikes the enemies finally returning to owner's hand.
``` // The hammer is unwielded.
The knight receives an enchanted sword. // The item's glow fades.
The sword is wielded.
The item spreads bloodlust.
The sword is swung.
The item eats the soul of enemies.
The sword is unwielded.
Bloodlust slowly disappears.
The valkyrie receives an enchanted hammer.
The hammer is wielded.
The item begins to glow faintly.
The hammer is swung.
The item flies and strikes the enemies finally returning to owner's hand.
The hammer is unwielded.
The item's glow fades.
``` ```
## Class diagram ## Class diagram

View File

@ -1,4 +1,4 @@
<?xml version="1.0" encoding="UTF-8"?> <?xml version="1.0"?>
<!-- <!--
The MIT License The MIT License
@ -23,27 +23,30 @@
THE SOFTWARE. THE SOFTWARE.
--> -->
<project xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd"> <project
<modelVersion>4.0.0</modelVersion> xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd"
<parent> xmlns="http://maven.apache.org/POM/4.0.0"
<groupId>com.iluwatar</groupId> xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance">
<artifactId>java-design-patterns</artifactId> <modelVersion>4.0.0</modelVersion>
<version>1.26.0-SNAPSHOT</version> <parent>
</parent> <groupId>com.iluwatar</groupId>
<artifactId>bridge</artifactId> <artifactId>java-design-patterns</artifactId>
<dependencies> <version>1.24.0-SNAPSHOT</version>
<dependency> </parent>
<groupId>org.junit.jupiter</groupId> <artifactId>bridge</artifactId>
<artifactId>junit-jupiter-engine</artifactId> <dependencies>
<scope>test</scope> <dependency>
</dependency> <groupId>org.junit.jupiter</groupId>
<dependency> <artifactId>junit-jupiter-engine</artifactId>
<groupId>org.mockito</groupId> <scope>test</scope>
<artifactId>mockito-core</artifactId> </dependency>
<scope>test</scope> <dependency>
</dependency> <groupId>org.mockito</groupId>
</dependencies> <artifactId>mockito-core</artifactId>
<build> <scope>test</scope>
</dependency>
</dependencies>
<build>
<plugins> <plugins>
<plugin> <plugin>
<groupId>org.apache.maven.plugins</groupId> <groupId>org.apache.maven.plugins</groupId>

View File

@ -43,7 +43,7 @@ public class Hammer implements Weapon {
@Override @Override
public void swing() { public void swing() {
LOGGER.info("The hammer is swung."); LOGGER.info("The hammer is swinged.");
enchantment.apply(); enchantment.apply();
} }

View File

@ -43,7 +43,7 @@ public class Sword implements Weapon {
@Override @Override
public void swing() { public void swing() {
LOGGER.info("The sword is swung."); LOGGER.info("The sword is swinged.");
enchantment.apply(); enchantment.apply();
} }

View File

@ -4,7 +4,6 @@ title: Builder
folder: builder folder: builder
permalink: /patterns/builder/ permalink: /patterns/builder/
categories: Creational categories: Creational
language: en
tags: tags:
- Gang of Four - Gang of Four
--- ---
@ -16,11 +15,11 @@ process can create different representations.
## Explanation ## Explanation
Real-world example Real world example
> Imagine a character generator for a role-playing game. The easiest option is to let the computer > Imagine a character generator for a role-playing game. The easiest option is to let the computer
> create the character for you. If you want to manually select the character details like > create the character for you. If you want to manually select the character details like
> profession, gender, hair color, etc. the character generation becomes a step-by-step process that > profession, gender, hair color etc. the character generation becomes a step-by-step process that
> completes when all the selections are ready. > completes when all the selections are ready.
In plain words In plain words
@ -49,7 +48,7 @@ anti-pattern.
**Programmatic Example** **Programmatic Example**
The sane alternative is to use the Builder pattern. First of all, we have our hero that we want to The sane alternative is to use the Builder pattern. First of all we have our hero that we want to
create: create:
```java ```java
@ -134,13 +133,7 @@ Use the Builder pattern when
* The algorithm for creating a complex object should be independent of the parts that make up the object and how they're assembled * The algorithm for creating a complex object should be independent of the parts that make up the object and how they're assembled
* The construction process must allow different representations for the object that's constructed * The construction process must allow different representations for the object that's constructed
## Tutorials ## Real world examples
* [Refactoring Guru](https://refactoring.guru/design-patterns/builder)
* [Oracle Blog](https://blogs.oracle.com/javamagazine/post/exploring-joshua-blochs-builder-design-pattern-in-java)
* [Journal Dev](https://www.journaldev.com/1425/builder-design-pattern-in-java)
## Known uses
* [java.lang.StringBuilder](http://docs.oracle.com/javase/8/docs/api/java/lang/StringBuilder.html) * [java.lang.StringBuilder](http://docs.oracle.com/javase/8/docs/api/java/lang/StringBuilder.html)
* [java.nio.ByteBuffer](http://docs.oracle.com/javase/8/docs/api/java/nio/ByteBuffer.html#put-byte-) as well as similar buffers such as FloatBuffer, IntBuffer and so on. * [java.nio.ByteBuffer](http://docs.oracle.com/javase/8/docs/api/java/nio/ByteBuffer.html#put-byte-) as well as similar buffers such as FloatBuffer, IntBuffer and so on.

View File

@ -1,4 +1,4 @@
<?xml version="1.0" encoding="UTF-8"?> <?xml version="1.0"?>
<!-- <!--
The MIT License The MIT License
@ -23,22 +23,25 @@
THE SOFTWARE. THE SOFTWARE.
--> -->
<project xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd"> <project
<modelVersion>4.0.0</modelVersion> xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd"
<parent> xmlns="http://maven.apache.org/POM/4.0.0"
<groupId>com.iluwatar</groupId> xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance">
<artifactId>java-design-patterns</artifactId> <modelVersion>4.0.0</modelVersion>
<version>1.26.0-SNAPSHOT</version> <parent>
</parent> <groupId>com.iluwatar</groupId>
<artifactId>builder</artifactId> <artifactId>java-design-patterns</artifactId>
<dependencies> <version>1.24.0-SNAPSHOT</version>
<dependency> </parent>
<groupId>org.junit.jupiter</groupId> <artifactId>builder</artifactId>
<artifactId>junit-jupiter-engine</artifactId> <dependencies>
<scope>test</scope> <dependency>
</dependency> <groupId>org.junit.jupiter</groupId>
</dependencies> <artifactId>junit-jupiter-engine</artifactId>
<build> <scope>test</scope>
</dependency>
</dependencies>
<build>
<plugins> <plugins>
<plugin> <plugin>
<groupId>org.apache.maven.plugins</groupId> <groupId>org.apache.maven.plugins</groupId>

View File

@ -4,7 +4,6 @@ title: Business Delegate
folder: business-delegate folder: business-delegate
permalink: /patterns/business-delegate/ permalink: /patterns/business-delegate/
categories: Structural categories: Structural
language: en
tags: tags:
- Decoupling - Decoupling
--- ---

View File

@ -1,4 +1,4 @@
<?xml version="1.0" encoding="UTF-8"?> <?xml version="1.0"?>
<!-- <!--
The MIT License The MIT License
@ -23,43 +23,46 @@
THE SOFTWARE. THE SOFTWARE.
--> -->
<project xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd"> <project
<modelVersion>4.0.0</modelVersion> xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd"
<parent> xmlns="http://maven.apache.org/POM/4.0.0"
<groupId>com.iluwatar</groupId> xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance">
<artifactId>java-design-patterns</artifactId> <modelVersion>4.0.0</modelVersion>
<version>1.26.0-SNAPSHOT</version> <parent>
</parent> <groupId>com.iluwatar</groupId>
<artifactId>business-delegate</artifactId> <artifactId>java-design-patterns</artifactId>
<dependencies> <version>1.24.0-SNAPSHOT</version>
<dependency> </parent>
<groupId>org.junit.jupiter</groupId> <artifactId>business-delegate</artifactId>
<artifactId>junit-jupiter-engine</artifactId> <dependencies>
<scope>test</scope> <dependency>
</dependency> <groupId>org.junit.jupiter</groupId>
<dependency> <artifactId>junit-jupiter-engine</artifactId>
<groupId>org.mockito</groupId> <scope>test</scope>
<artifactId>mockito-core</artifactId> </dependency>
<scope>test</scope> <dependency>
</dependency> <groupId>org.mockito</groupId>
</dependencies> <artifactId>mockito-core</artifactId>
<build> <scope>test</scope>
<plugins> </dependency>
<plugin> </dependencies>
<groupId>org.apache.maven.plugins</groupId> <build>
<artifactId>maven-assembly-plugin</artifactId> <plugins>
<executions> <plugin>
<execution> <groupId>org.apache.maven.plugins</groupId>
<configuration> <artifactId>maven-assembly-plugin</artifactId>
<archive> <executions>
<manifest> <execution>
<mainClass>com.iluwatar.business.delegate.App</mainClass> <configuration>
</manifest> <archive>
</archive> <manifest>
</configuration> <mainClass>com.iluwatar.business.delegate.App</mainClass>
</execution> </manifest>
</executions> </archive>
</plugin> </configuration>
</plugins> </execution>
</build> </executions>
</plugin>
</plugins>
</build>
</project> </project>

View File

@ -4,240 +4,23 @@ title: Bytecode
folder: bytecode folder: bytecode
permalink: /patterns/bytecode/ permalink: /patterns/bytecode/
categories: Behavioral categories: Behavioral
language: en
tags: tags:
- Game programming - Game programming
--- ---
## Intent ## Intent
Allows to encode behaviour as instructions for virtual machine.
Allows encoding behavior as instructions for a virtual machine.
## Explanation
Real world example
> A team is working on a new game where wizards battle against each other. The wizard behavior
> needs to be carefully adjusted and iterated hundreds of times through playtesting. It's not
> optimal to ask the programmer to make changes each time the game designer wants to vary the
> behavior, so the wizard behavior is implemented as a data-driven virtual machine.
In plain words
> Bytecode pattern enables behavior driven by data instead of code.
[Gameprogrammingpatterns.com](https://gameprogrammingpatterns.com/bytecode.html) documentation
states:
> An instruction set defines the low-level operations that can be performed. A series of
> instructions is encoded as a sequence of bytes. A virtual machine executes these instructions one
> at a time, using a stack for intermediate values. By combining instructions, complex high-level
> behavior can be defined.
**Programmatic Example**
One of the most important game objects is the `Wizard` class.
```java
@AllArgsConstructor
@Setter
@Getter
@Slf4j
public class Wizard {
private int health;
private int agility;
private int wisdom;
private int numberOfPlayedSounds;
private int numberOfSpawnedParticles;
public void playSound() {
LOGGER.info("Playing sound");
numberOfPlayedSounds++;
}
public void spawnParticles() {
LOGGER.info("Spawning particles");
numberOfSpawnedParticles++;
}
}
```
Next, we show the available instructions for our virtual machine. Each of the instructions has its
own semantics on how it operates with the stack data. For example, the ADD instruction takes the top
two items from the stack, adds them together and pushes the result to the stack.
```java
@AllArgsConstructor
@Getter
public enum Instruction {
LITERAL(1), // e.g. "LITERAL 0", push 0 to stack
SET_HEALTH(2), // e.g. "SET_HEALTH", pop health and wizard number, call set health
SET_WISDOM(3), // e.g. "SET_WISDOM", pop wisdom and wizard number, call set wisdom
SET_AGILITY(4), // e.g. "SET_AGILITY", pop agility and wizard number, call set agility
PLAY_SOUND(5), // e.g. "PLAY_SOUND", pop value as wizard number, call play sound
SPAWN_PARTICLES(6), // e.g. "SPAWN_PARTICLES", pop value as wizard number, call spawn particles
GET_HEALTH(7), // e.g. "GET_HEALTH", pop value as wizard number, push wizard's health
GET_AGILITY(8), // e.g. "GET_AGILITY", pop value as wizard number, push wizard's agility
GET_WISDOM(9), // e.g. "GET_WISDOM", pop value as wizard number, push wizard's wisdom
ADD(10), // e.g. "ADD", pop 2 values, push their sum
DIVIDE(11); // e.g. "DIVIDE", pop 2 values, push their division
// ...
}
```
At the heart of our example is the `VirtualMachine` class. It takes instructions as input and
executes them to provide the game object behavior.
```java
@Getter
@Slf4j
public class VirtualMachine {
private final Stack<Integer> stack = new Stack<>();
private final Wizard[] wizards = new Wizard[2];
public VirtualMachine() {
wizards[0] = new Wizard(randomInt(3, 32), randomInt(3, 32), randomInt(3, 32),
0, 0);
wizards[1] = new Wizard(randomInt(3, 32), randomInt(3, 32), randomInt(3, 32),
0, 0);
}
public VirtualMachine(Wizard wizard1, Wizard wizard2) {
wizards[0] = wizard1;
wizards[1] = wizard2;
}
public void execute(int[] bytecode) {
for (var i = 0; i < bytecode.length; i++) {
Instruction instruction = Instruction.getInstruction(bytecode[i]);
switch (instruction) {
case LITERAL:
// Read the next byte from the bytecode.
int value = bytecode[++i];
// Push the next value to stack
stack.push(value);
break;
case SET_AGILITY:
var amount = stack.pop();
var wizard = stack.pop();
setAgility(wizard, amount);
break;
case SET_WISDOM:
amount = stack.pop();
wizard = stack.pop();
setWisdom(wizard, amount);
break;
case SET_HEALTH:
amount = stack.pop();
wizard = stack.pop();
setHealth(wizard, amount);
break;
case GET_HEALTH:
wizard = stack.pop();
stack.push(getHealth(wizard));
break;
case GET_AGILITY:
wizard = stack.pop();
stack.push(getAgility(wizard));
break;
case GET_WISDOM:
wizard = stack.pop();
stack.push(getWisdom(wizard));
break;
case ADD:
var a = stack.pop();
var b = stack.pop();
stack.push(a + b);
break;
case DIVIDE:
a = stack.pop();
b = stack.pop();
stack.push(b / a);
break;
case PLAY_SOUND:
wizard = stack.pop();
getWizards()[wizard].playSound();
break;
case SPAWN_PARTICLES:
wizard = stack.pop();
getWizards()[wizard].spawnParticles();
break;
default:
throw new IllegalArgumentException("Invalid instruction value");
}
LOGGER.info("Executed " + instruction.name() + ", Stack contains " + getStack());
}
}
public void setHealth(int wizard, int amount) {
wizards[wizard].setHealth(amount);
}
// other setters ->
// ...
}
```
Now we can show the full example utilizing the virtual machine.
```java
public static void main(String[] args) {
var vm = new VirtualMachine(
new Wizard(45, 7, 11, 0, 0),
new Wizard(36, 18, 8, 0, 0));
vm.execute(InstructionConverterUtil.convertToByteCode("LITERAL 0"));
vm.execute(InstructionConverterUtil.convertToByteCode("LITERAL 0"));
vm.execute(InstructionConverterUtil.convertToByteCode("GET_HEALTH"));
vm.execute(InstructionConverterUtil.convertToByteCode("LITERAL 0"));
vm.execute(InstructionConverterUtil.convertToByteCode("GET_AGILITY"));
vm.execute(InstructionConverterUtil.convertToByteCode("LITERAL 0"));
vm.execute(InstructionConverterUtil.convertToByteCode("GET_WISDOM"));
vm.execute(InstructionConverterUtil.convertToByteCode("ADD"));
vm.execute(InstructionConverterUtil.convertToByteCode("LITERAL 2"));
vm.execute(InstructionConverterUtil.convertToByteCode("DIVIDE"));
vm.execute(InstructionConverterUtil.convertToByteCode("ADD"));
vm.execute(InstructionConverterUtil.convertToByteCode("SET_HEALTH"));
}
```
Here is the console output.
```
16:20:10.193 [main] INFO com.iluwatar.bytecode.VirtualMachine - Executed LITERAL, Stack contains [0]
16:20:10.196 [main] INFO com.iluwatar.bytecode.VirtualMachine - Executed LITERAL, Stack contains [0, 0]
16:20:10.197 [main] INFO com.iluwatar.bytecode.VirtualMachine - Executed GET_HEALTH, Stack contains [0, 45]
16:20:10.197 [main] INFO com.iluwatar.bytecode.VirtualMachine - Executed LITERAL, Stack contains [0, 45, 0]
16:20:10.197 [main] INFO com.iluwatar.bytecode.VirtualMachine - Executed GET_AGILITY, Stack contains [0, 45, 7]
16:20:10.197 [main] INFO com.iluwatar.bytecode.VirtualMachine - Executed LITERAL, Stack contains [0, 45, 7, 0]
16:20:10.197 [main] INFO com.iluwatar.bytecode.VirtualMachine - Executed GET_WISDOM, Stack contains [0, 45, 7, 11]
16:20:10.197 [main] INFO com.iluwatar.bytecode.VirtualMachine - Executed ADD, Stack contains [0, 45, 18]
16:20:10.197 [main] INFO com.iluwatar.bytecode.VirtualMachine - Executed LITERAL, Stack contains [0, 45, 18, 2]
16:20:10.198 [main] INFO com.iluwatar.bytecode.VirtualMachine - Executed DIVIDE, Stack contains [0, 45, 9]
16:20:10.198 [main] INFO com.iluwatar.bytecode.VirtualMachine - Executed ADD, Stack contains [0, 54]
16:20:10.198 [main] INFO com.iluwatar.bytecode.VirtualMachine - Executed SET_HEALTH, Stack contains []
```
## Class diagram ## Class diagram
![alt text](./etc/bytecode.urm.png "Bytecode class diagram") ![alt text](./etc/bytecode.urm.png "Bytecode class diagram")
## Applicability ## Applicability
Use the Bytecode pattern when you have a lot of behavior you need to define and your Use the Bytecode pattern when you have a lot of behavior you need to define and your
games implementation language isnt a good fit because: games implementation language isnt a good fit because:
* Its too low-level, making it tedious or error-prone to program in. * its too low-level, making it tedious or error-prone to program in.
* Iterating on it takes too long due to slow compile times or other tooling issues. * iterating on it takes too long due to slow compile times or other tooling issues.
* It has too much trust. If you want to ensure the behavior being defined cant break the game, you need to sandbox it from the rest of the codebase. * it has too much trust. If you want to ensure the behavior being defined cant break the game, you need to sandbox it from the rest of the codebase.
## Related patterns
* [Interpreter](https://java-design-patterns.com/patterns/interpreter/)
## Credits ## Credits

BIN
bytecode/etc/bytecode.png Normal file

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@ -0,0 +1,49 @@
<?xml version="1.0" encoding="UTF-8"?>
<class-diagram version="1.2.3" icons="true" always-add-relationships="false" generalizations="true" realizations="true"
associations="true" dependencies="false" nesting-relationships="true" router="FAN">
<class id="1" language="java" name="com.iluwatar.bytecode.VirtualMachine" project="bytecode"
file="/bytecode/src/main/java/com/iluwatar/bytecode/VirtualMachine.java" binary="false" corner="BOTTOM_RIGHT">
<position height="-1" width="-1" x="455" y="173"/>
<display autosize="true" stereotype="true" package="true" initial-value="false" signature="true"
sort-features="false" accessors="true" visibility="true">
<attributes public="true" package="true" protected="true" private="true" static="true"/>
<operations public="true" package="true" protected="true" private="true" static="true"/>
</display>
</class>
<class id="2" language="java" name="com.iluwatar.bytecode.App" project="bytecode"
file="/bytecode/src/main/java/com/iluwatar/bytecode/App.java" binary="false" corner="BOTTOM_RIGHT">
<position height="-1" width="-1" x="148" y="110"/>
<display autosize="true" stereotype="true" package="true" initial-value="false" signature="true"
sort-features="false" accessors="true" visibility="true">
<attributes public="true" package="true" protected="true" private="true" static="true"/>
<operations public="true" package="true" protected="true" private="true" static="true"/>
</display>
</class>
<class id="3" language="java" name="com.iluwatar.bytecode.Wizard" project="bytecode"
file="/bytecode/src/main/java/com/iluwatar/bytecode/Wizard.java" binary="false" corner="BOTTOM_RIGHT">
<position height="-1" width="-1" x="148" y="416"/>
<display autosize="true" stereotype="true" package="true" initial-value="false" signature="true"
sort-features="false" accessors="true" visibility="true">
<attributes public="true" package="true" protected="true" private="true" static="true"/>
<operations public="true" package="true" protected="true" private="true" static="true"/>
</display>
</class>
<association id="4">
<end type="SOURCE" refId="1" navigable="false" variant="ASSOCIATION">
<attribute id="5" name="wizards">
<position height="18" width="48" x="296" y="291"/>
</attribute>
<multiplicity id="6" minimum="0" maximum="2147483647">
<position height="0" width="0" x="-327" y="-27"/>
</multiplicity>
</end>
<end type="TARGET" refId="3" navigable="true" variant="ASSOCIATION"/>
<display labels="true" multiplicity="true"/>
</association>
<classifier-display autosize="true" stereotype="true" package="true" initial-value="false" signature="true"
sort-features="false" accessors="true" visibility="true">
<attributes public="true" package="true" protected="true" private="true" static="true"/>
<operations public="true" package="true" protected="true" private="true" static="true"/>
</classifier-display>
<association-display labels="true" multiplicity="true"/>
</class-diagram>

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@ -3,6 +3,7 @@ package com.iluwatar.bytecode {
class App { class App {
- LOGGER : Logger {static} - LOGGER : Logger {static}
+ App() + App()
- interpretInstruction(instruction : String, vm : VirtualMachine) {static}
+ main(args : String[]) {static} + main(args : String[]) {static}
} }
enum Instruction { enum Instruction {
@ -17,25 +18,22 @@ package com.iluwatar.bytecode {
+ SET_HEALTH {static} + SET_HEALTH {static}
+ SET_WISDOM {static} + SET_WISDOM {static}
+ SPAWN_PARTICLES {static} + SPAWN_PARTICLES {static}
- intValue : int - value : int
+ getInstruction(value : int) : Instruction {static} + getInstruction(value : int) : Instruction {static}
+ getIntValue() : int + getIntValue() : int
+ valueOf(name : String) : Instruction {static} + valueOf(name : String) : Instruction {static}
+ values() : Instruction[] {static} + values() : Instruction[] {static}
} }
class VirtualMachine { class VirtualMachine {
- LOGGER : Logger {static}
- stack : Stack<Integer> - stack : Stack<Integer>
- wizards : Wizard[] - wizards : Wizard[]
+ VirtualMachine() + VirtualMachine()
+ VirtualMachine(wizard1 : Wizard, wizard2 : Wizard)
+ execute(bytecode : int[]) + execute(bytecode : int[])
+ getAgility(wizard : int) : int + getAgility(wizard : int) : int
+ getHealth(wizard : int) : int + getHealth(wizard : int) : int
+ getStack() : Stack<Integer> + getStack() : Stack<Integer>
+ getWisdom(wizard : int) : int + getWisdom(wizard : int) : int
+ getWizards() : Wizard[] + getWizards() : Wizard[]
- randomInt(min : int, max : int) : int
+ setAgility(wizard : int, amount : int) + setAgility(wizard : int, amount : int)
+ setHealth(wizard : int, amount : int) + setHealth(wizard : int, amount : int)
+ setWisdom(wizard : int, amount : int) + setWisdom(wizard : int, amount : int)
@ -47,7 +45,7 @@ package com.iluwatar.bytecode {
- numberOfPlayedSounds : int - numberOfPlayedSounds : int
- numberOfSpawnedParticles : int - numberOfSpawnedParticles : int
- wisdom : int - wisdom : int
+ Wizard(health : int, agility : int, wisdom : int, numberOfPlayedSounds : int, numberOfSpawnedParticles : int) + Wizard()
+ getAgility() : int + getAgility() : int
+ getHealth() : int + getHealth() : int
+ getNumberOfPlayedSounds() : int + getNumberOfPlayedSounds() : int
@ -56,8 +54,6 @@ package com.iluwatar.bytecode {
+ playSound() + playSound()
+ setAgility(agility : int) + setAgility(agility : int)
+ setHealth(health : int) + setHealth(health : int)
+ setNumberOfPlayedSounds(numberOfPlayedSounds : int)
+ setNumberOfSpawnedParticles(numberOfSpawnedParticles : int)
+ setWisdom(wisdom : int) + setWisdom(wisdom : int)
+ spawnParticles() + spawnParticles()
} }

View File

@ -23,38 +23,43 @@
THE SOFTWARE. THE SOFTWARE.
--> -->
<project xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd"> <project xmlns="http://maven.apache.org/POM/4.0.0"
<parent> xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
<artifactId>java-design-patterns</artifactId> xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
<groupId>com.iluwatar</groupId> <parent>
<version>1.26.0-SNAPSHOT</version> <artifactId>java-design-patterns</artifactId>
</parent> <groupId>com.iluwatar</groupId>
<modelVersion>4.0.0</modelVersion> <version>1.24.0-SNAPSHOT</version>
<artifactId>bytecode</artifactId> </parent>
<dependencies> <modelVersion>4.0.0</modelVersion>
<dependency>
<groupId>org.junit.jupiter</groupId> <artifactId>bytecode</artifactId>
<artifactId>junit-jupiter-engine</artifactId> <dependencies>
<scope>test</scope> <dependency>
</dependency> <groupId>org.junit.jupiter</groupId>
</dependencies> <artifactId>junit-jupiter-engine</artifactId>
<build> <scope>test</scope>
<plugins> </dependency>
<plugin> </dependencies>
<groupId>org.apache.maven.plugins</groupId>
<artifactId>maven-assembly-plugin</artifactId> <build>
<executions> <plugins>
<execution> <plugin>
<configuration> <groupId>org.apache.maven.plugins</groupId>
<archive> <artifactId>maven-assembly-plugin</artifactId>
<manifest> <executions>
<mainClass>com.iluwatar.bytecode.App</mainClass> <execution>
</manifest> <configuration>
</archive> <archive>
</configuration> <manifest>
</execution> <mainClass>com.iluwatar.bytecode.App</mainClass>
</executions> </manifest>
</plugin> </archive>
</plugins> </configuration>
</build> </execution>
</project> </executions>
</plugin>
</plugins>
</build>
</project>

View File

@ -42,14 +42,6 @@ import lombok.extern.slf4j.Slf4j;
@Slf4j @Slf4j
public class App { public class App {
private static final String LITERAL_0 = "LITERAL 0";
private static final String HEALTH_PATTERN = "%s_HEALTH";
private static final String GET_AGILITY = "GET_AGILITY";
private static final String GET_WISDOM = "GET_WISDOM";
private static final String ADD = "ADD";
private static final String LITERAL_2 = "LITERAL 2";
private static final String DIVIDE = "DIVIDE";
/** /**
* Main app method. * Main app method.
* *
@ -57,21 +49,33 @@ public class App {
*/ */
public static void main(String[] args) { public static void main(String[] args) {
var vm = new VirtualMachine( var wizard = new Wizard();
new Wizard(45, 7, 11, 0, 0), wizard.setHealth(45);
new Wizard(36, 18, 8, 0, 0)); wizard.setAgility(7);
wizard.setWisdom(11);
vm.execute(InstructionConverterUtil.convertToByteCode(LITERAL_0)); var vm = new VirtualMachine();
vm.execute(InstructionConverterUtil.convertToByteCode(LITERAL_0)); vm.getWizards()[0] = wizard;
vm.execute(InstructionConverterUtil.convertToByteCode(String.format(HEALTH_PATTERN, "GET")));
vm.execute(InstructionConverterUtil.convertToByteCode(LITERAL_0)); String literal = "LITERAL 0";
vm.execute(InstructionConverterUtil.convertToByteCode(GET_AGILITY));
vm.execute(InstructionConverterUtil.convertToByteCode(LITERAL_0)); interpretInstruction(literal, vm);
vm.execute(InstructionConverterUtil.convertToByteCode(GET_WISDOM)); interpretInstruction(literal, vm);
vm.execute(InstructionConverterUtil.convertToByteCode(ADD)); interpretInstruction("GET_HEALTH", vm);
vm.execute(InstructionConverterUtil.convertToByteCode(LITERAL_2)); interpretInstruction(literal, vm);
vm.execute(InstructionConverterUtil.convertToByteCode(DIVIDE)); interpretInstruction("GET_AGILITY", vm);
vm.execute(InstructionConverterUtil.convertToByteCode(ADD)); interpretInstruction(literal, vm);
vm.execute(InstructionConverterUtil.convertToByteCode(String.format(HEALTH_PATTERN, "SET"))); interpretInstruction("GET_WISDOM ", vm);
interpretInstruction("ADD", vm);
interpretInstruction("LITERAL 2", vm);
interpretInstruction("DIVIDE", vm);
interpretInstruction("ADD", vm);
interpretInstruction("SET_HEALTH", vm);
}
private static void interpretInstruction(String instruction, VirtualMachine vm) {
vm.execute(InstructionConverterUtil.convertToByteCode(instruction));
var stack = vm.getStack();
LOGGER.info(instruction + String.format("%" + (12 - instruction.length()) + "s", "") + stack);
} }
} }

View File

@ -33,17 +33,17 @@ import lombok.Getter;
@Getter @Getter
public enum Instruction { public enum Instruction {
LITERAL(1), // e.g. "LITERAL 0", push 0 to stack LITERAL(1),
SET_HEALTH(2), // e.g. "SET_HEALTH", pop health and wizard number, call set health SET_HEALTH(2),
SET_WISDOM(3), // e.g. "SET_WISDOM", pop wisdom and wizard number, call set wisdom SET_WISDOM(3),
SET_AGILITY(4), // e.g. "SET_AGILITY", pop agility and wizard number, call set agility SET_AGILITY(4),
PLAY_SOUND(5), // e.g. "PLAY_SOUND", pop value as wizard number, call play sound PLAY_SOUND(5),
SPAWN_PARTICLES(6), // e.g. "SPAWN_PARTICLES", pop value as wizard number, call spawn particles SPAWN_PARTICLES(6),
GET_HEALTH(7), // e.g. "GET_HEALTH", pop value as wizard number, push wizard's health GET_HEALTH(7),
GET_AGILITY(8), // e.g. "GET_AGILITY", pop value as wizard number, push wizard's agility GET_AGILITY(8),
GET_WISDOM(9), // e.g. "GET_WISDOM", pop value as wizard number, push wizard's wisdom GET_WISDOM(9),
ADD(10), // e.g. "ADD", pop 2 values, push their sum ADD(10),
DIVIDE(11); // e.g. "DIVIDE", pop 2 values, push their division DIVIDE(11);
private final int intValue; private final int intValue;

View File

@ -24,15 +24,12 @@
package com.iluwatar.bytecode; package com.iluwatar.bytecode;
import java.util.Stack; import java.util.Stack;
import java.util.concurrent.ThreadLocalRandom;
import lombok.Getter; import lombok.Getter;
import lombok.extern.slf4j.Slf4j;
/** /**
* Implementation of virtual machine. * Implementation of virtual machine.
*/ */
@Getter @Getter
@Slf4j
public class VirtualMachine { public class VirtualMachine {
private final Stack<Integer> stack = new Stack<>(); private final Stack<Integer> stack = new Stack<>();
@ -40,21 +37,12 @@ public class VirtualMachine {
private final Wizard[] wizards = new Wizard[2]; private final Wizard[] wizards = new Wizard[2];
/** /**
* No-args constructor. * Constructor.
*/ */
public VirtualMachine() { public VirtualMachine() {
wizards[0] = new Wizard(randomInt(3, 32), randomInt(3, 32), randomInt(3, 32), for (var i = 0; i < wizards.length; i++) {
0, 0); wizards[i] = new Wizard();
wizards[1] = new Wizard(randomInt(3, 32), randomInt(3, 32), randomInt(3, 32), }
0, 0);
}
/**
* Constructor taking the wizards as arguments.
*/
public VirtualMachine(Wizard wizard1, Wizard wizard2) {
wizards[0] = wizard1;
wizards[1] = wizard2;
} }
/** /**
@ -69,7 +57,6 @@ public class VirtualMachine {
case LITERAL: case LITERAL:
// Read the next byte from the bytecode. // Read the next byte from the bytecode.
int value = bytecode[++i]; int value = bytecode[++i];
// Push the next value to stack
stack.push(value); stack.push(value);
break; break;
case SET_AGILITY: case SET_AGILITY:
@ -120,7 +107,6 @@ public class VirtualMachine {
default: default:
throw new IllegalArgumentException("Invalid instruction value"); throw new IllegalArgumentException("Invalid instruction value");
} }
LOGGER.info("Executed " + instruction.name() + ", Stack contains " + getStack());
} }
} }
@ -147,8 +133,4 @@ public class VirtualMachine {
public int getAgility(int wizard) { public int getAgility(int wizard) {
return wizards[wizard].getAgility(); return wizards[wizard].getAgility();
} }
private int randomInt(int min, int max) {
return ThreadLocalRandom.current().nextInt(min, max + 1);
}
} }

View File

@ -23,7 +23,6 @@
package com.iluwatar.bytecode; package com.iluwatar.bytecode;
import lombok.AllArgsConstructor;
import lombok.Getter; import lombok.Getter;
import lombok.Setter; import lombok.Setter;
import lombok.extern.slf4j.Slf4j; import lombok.extern.slf4j.Slf4j;
@ -32,15 +31,16 @@ import lombok.extern.slf4j.Slf4j;
* This class represent game objects which properties can be changed by instructions interpreted by * This class represent game objects which properties can be changed by instructions interpreted by
* virtual machine. * virtual machine.
*/ */
@AllArgsConstructor
@Setter @Setter
@Getter @Getter
@Slf4j @Slf4j
public class Wizard { public class Wizard {
private int health; private int health;
private int agility; private int agility;
private int wisdom; private int wisdom;
private int numberOfPlayedSounds; private int numberOfPlayedSounds;
private int numberOfSpawnedParticles; private int numberOfSpawnedParticles;
@ -53,4 +53,5 @@ public class Wizard {
LOGGER.info("Spawning particles"); LOGGER.info("Spawning particles");
numberOfSpawnedParticles++; numberOfSpawnedParticles++;
} }
} }

View File

@ -73,4 +73,6 @@ public class InstructionConverterUtil {
return false; return false;
} }
} }
} }

View File

@ -4,342 +4,26 @@ title: Caching
folder: caching folder: caching
permalink: /patterns/caching/ permalink: /patterns/caching/
categories: Behavioral categories: Behavioral
language: en
tags: tags:
- Performance - Performance
- Cloud distributed - Cloud distributed
--- ---
## Intent ## Intent
To avoid expensive re-acquisition of resources by not releasing
The caching pattern avoids expensive re-acquisition of resources by not releasing them immediately the resources immediately after their use. The resources retain their identity, are kept in some
after use. The resources retain their identity, are kept in some fast-access storage, and are fast-access storage, and are re-used to avoid having to acquire them again.
re-used to avoid having to acquire them again.
## Explanation
Real world example
> A team is working on a website that provides new homes for abandoned cats. People can post their
> cats on the website after registering, but all the new posts require approval from one of the
> site moderators. The user accounts of the site moderators contain a specific flag and the data
> is stored in a MongoDB database. Checking for the moderator flag each time a post is viewed
> becomes expensive and it's a good idea to utilize caching here.
In plain words
> Caching pattern keeps frequently needed data in fast-access storage to improve performance.
Wikipedia says:
> In computing, a cache is a hardware or software component that stores data so that future
> requests for that data can be served faster; the data stored in a cache might be the result of
> an earlier computation or a copy of data stored elsewhere. A cache hit occurs when the requested
> data can be found in a cache, while a cache miss occurs when it cannot. Cache hits are served by
> reading data from the cache, which is faster than recomputing a result or reading from a slower
> data store; thus, the more requests that can be served from the cache, the faster the system
> performs.
**Programmatic Example**
Let's first look at the data layer of our application. The interesting classes are `UserAccount`
which is a simple Java object containing the user account details, and `DbManager` interface which handles
reading and writing of these objects to/from database.
```java
@Data
@AllArgsConstructor
@ToString
@EqualsAndHashCode
public class UserAccount {
private String userId;
private String userName;
private String additionalInfo;
}
public interface DbManager {
void connect();
void disconnect();
UserAccount readFromDb(String userId);
UserAccount writeToDb(UserAccount userAccount);
UserAccount updateDb(UserAccount userAccount);
UserAccount upsertDb(UserAccount userAccount);
}
```
In the example, we are demonstrating various different caching policies
* Write-through writes data to the cache and DB in a single transaction
* Write-around writes data immediately into the DB instead of the cache
* Write-behind writes data into the cache initially whilst the data is only written into the DB
when the cache is full
* Cache-aside pushes the responsibility of keeping the data synchronized in both data sources to
the application itself
* Read-through strategy is also included in the aforementioned strategies and it returns data from
the cache to the caller if it exists, otherwise queries from DB and stores it into the cache for
future use.
The cache implementation in `LruCache` is a hash table accompanied by a doubly
linked-list. The linked-list helps in capturing and maintaining the LRU data in the cache. When
data is queried (from the cache), added (to the cache), or updated, the data is moved to the front
of the list to depict itself as the most-recently-used data. The LRU data is always at the end of
the list.
```java
@Slf4j
public class LruCache {
static class Node {
String userId;
UserAccount userAccount;
Node previous;
Node next;
public Node(String userId, UserAccount userAccount) {
this.userId = userId;
this.userAccount = userAccount;
}
}
/* ... omitted details ... */
public LruCache(int capacity) {
this.capacity = capacity;
}
public UserAccount get(String userId) {
if (cache.containsKey(userId)) {
var node = cache.get(userId);
remove(node);
setHead(node);
return node.userAccount;
}
return null;
}
public void set(String userId, UserAccount userAccount) {
if (cache.containsKey(userId)) {
var old = cache.get(userId);
old.userAccount = userAccount;
remove(old);
setHead(old);
} else {
var newNode = new Node(userId, userAccount);
if (cache.size() >= capacity) {
LOGGER.info("# Cache is FULL! Removing {} from cache...", end.userId);
cache.remove(end.userId); // remove LRU data from cache.
remove(end);
setHead(newNode);
} else {
setHead(newNode);
}
cache.put(userId, newNode);
}
}
public boolean contains(String userId) {
return cache.containsKey(userId);
}
public void remove(Node node) { /* ... */ }
public void setHead(Node node) { /* ... */ }
public void invalidate(String userId) { /* ... */ }
public boolean isFull() { /* ... */ }
public UserAccount getLruData() { /* ... */ }
public void clear() { /* ... */ }
public List<UserAccount> getCacheDataInListForm() { /* ... */ }
public void setCapacity(int newCapacity) { /* ... */ }
}
```
The next layer we are going to look at is `CacheStore` which implements the different caching
strategies.
```java
@Slf4j
public class CacheStore {
private static final int CAPACITY = 3;
private static LruCache cache;
private final DbManager dbManager;
/* ... details omitted ... */
public UserAccount readThrough(final String userId) {
if (cache.contains(userId)) {
LOGGER.info("# Found in Cache!");
return cache.get(userId);
}
LOGGER.info("# Not found in cache! Go to DB!!");
UserAccount userAccount = dbManager.readFromDb(userId);
cache.set(userId, userAccount);
return userAccount;
}
public void writeThrough(final UserAccount userAccount) {
if (cache.contains(userAccount.getUserId())) {
dbManager.updateDb(userAccount);
} else {
dbManager.writeToDb(userAccount);
}
cache.set(userAccount.getUserId(), userAccount);
}
public void writeAround(final UserAccount userAccount) {
if (cache.contains(userAccount.getUserId())) {
dbManager.updateDb(userAccount);
// Cache data has been updated -- remove older
cache.invalidate(userAccount.getUserId());
// version from cache.
} else {
dbManager.writeToDb(userAccount);
}
}
public static void clearCache() {
if (cache != null) {
cache.clear();
}
}
public static void flushCache() {
LOGGER.info("# flushCache...");
Optional.ofNullable(cache)
.map(LruCache::getCacheDataInListForm)
.orElse(List.of())
.forEach(DbManager::updateDb);
}
/* ... omitted the implementation of other caching strategies ... */
}
```
`AppManager` helps to bridge the gap in communication between the main class and the application's
back-end. DB connection is initialized through this class. The chosen caching strategy/policy is
also initialized here. Before the cache can be used, the size of the cache has to be set. Depending
on the chosen caching policy, `AppManager` will call the appropriate function in the `CacheStore`
class.
```java
@Slf4j
public final class AppManager {
private static CachingPolicy cachingPolicy;
private final DbManager dbManager;
private final CacheStore cacheStore;
private AppManager() {
}
public void initDb() { /* ... */ }
public static void initCachingPolicy(CachingPolicy policy) { /* ... */ }
public static void initCacheCapacity(int capacity) { /* ... */ }
public UserAccount find(final String userId) {
LOGGER.info("Trying to find {} in cache", userId);
if (cachingPolicy == CachingPolicy.THROUGH
|| cachingPolicy == CachingPolicy.AROUND) {
return cacheStore.readThrough(userId);
} else if (cachingPolicy == CachingPolicy.BEHIND) {
return cacheStore.readThroughWithWriteBackPolicy(userId);
} else if (cachingPolicy == CachingPolicy.ASIDE) {
return findAside(userId);
}
return null;
}
public void save(final UserAccount userAccount) {
LOGGER.info("Save record!");
if (cachingPolicy == CachingPolicy.THROUGH) {
cacheStore.writeThrough(userAccount);
} else if (cachingPolicy == CachingPolicy.AROUND) {
cacheStore.writeAround(userAccount);
} else if (cachingPolicy == CachingPolicy.BEHIND) {
cacheStore.writeBehind(userAccount);
} else if (cachingPolicy == CachingPolicy.ASIDE) {
saveAside(userAccount);
}
}
public static String printCacheContent() {
return CacheStore.print();
}
/* ... details omitted ... */
}
```
Here is what we do in the main class of the application.
```java
@Slf4j
public class App {
public static void main(final String[] args) {
boolean isDbMongo = isDbMongo(args);
if(isDbMongo){
LOGGER.info("Using the Mongo database engine to run the application.");
} else {
LOGGER.info("Using the 'in Memory' database to run the application.");
}
App app = new App(isDbMongo);
app.useReadAndWriteThroughStrategy();
String splitLine = "==============================================";
LOGGER.info(splitLine);
app.useReadThroughAndWriteAroundStrategy();
LOGGER.info(splitLine);
app.useReadThroughAndWriteBehindStrategy();
LOGGER.info(splitLine);
app.useCacheAsideStategy();
LOGGER.info(splitLine);
}
public void useReadAndWriteThroughStrategy() {
LOGGER.info("# CachingPolicy.THROUGH");
appManager.initCachingPolicy(CachingPolicy.THROUGH);
var userAccount1 = new UserAccount("001", "John", "He is a boy.");
appManager.save(userAccount1);
LOGGER.info(appManager.printCacheContent());
appManager.find("001");
appManager.find("001");
}
public void useReadThroughAndWriteAroundStrategy() { /* ... */ }
public void useReadThroughAndWriteBehindStrategy() { /* ... */ }
public void useCacheAsideStategy() { /* ... */ }
}
```
## Class diagram ## Class diagram
![alt text](./etc/caching.png "Caching") ![alt text](./etc/caching.png "Caching")
## Applicability ## Applicability
Use the Caching pattern(s) when Use the Caching pattern(s) when
* Repetitious acquisition, initialization, and release of the same resource cause unnecessary * Repetitious acquisition, initialization, and release of the same resource causes unnecessary performance overhead.
performance overhead.
## Related patterns
* [Proxy](https://java-design-patterns.com/patterns/proxy/)
## Credits ## Credits
* [Write-through, write-around, write-back: Cache explained](http://www.computerweekly.com/feature/Write-through-write-around-write-back-Cache-explained) * [Write-through, write-around, write-back: Cache explained](http://www.computerweekly.com/feature/Write-through-write-around-write-back-Cache-explained)
* [Read-Through, Write-Through, Write-Behind, and Refresh-Ahead Caching](https://docs.oracle.com/cd/E15357_01/coh.360/e15723/cache_rtwtwbra.htm#COHDG5177) * [Read-Through, Write-Through, Write-Behind, and Refresh-Ahead Caching](https://docs.oracle.com/cd/E15357_01/coh.360/e15723/cache_rtwtwbra.htm#COHDG5177)
* [Cache-Aside pattern](https://docs.microsoft.com/en-us/azure/architecture/patterns/cache-aside) * [Cache-Aside pattern](https://docs.microsoft.com/en-us/azure/architecture/patterns/cache-aside)
* [Java EE 8 High Performance: Master techniques such as memory optimization, caching, concurrency, and multithreading to achieve maximum performance from your enterprise applications](https://www.amazon.com/gp/product/178847306X/ref=as_li_qf_asin_il_tl?ie=UTF8&tag=javadesignpat-20&creative=9325&linkCode=as2&creativeASIN=178847306X&linkId=e948720055599f248cdac47da9125ff4)
* [Java Performance: In-Depth Advice for Tuning and Programming Java 8, 11, and Beyond](https://www.amazon.com/gp/product/1492056111/ref=as_li_qf_asin_il_tl?ie=UTF8&tag=javadesignpat-20&creative=9325&linkCode=as2&creativeASIN=1492056111&linkId=7e553581559b9ec04221259e52004b08)
* [Effective Java](https://www.amazon.com/gp/product/B078H61SCH/ref=as_li_qf_asin_il_tl?ie=UTF8&tag=javadesignpat-20&creative=9325&linkCode=as2&creativeASIN=B078H61SCH&linkId=f06607a0b48c76541ef19c5b8b9e7882)
* [Java Performance: The Definitive Guide: Getting the Most Out of Your Code](https://www.amazon.com/gp/product/1449358454/ref=as_li_qf_asin_il_tl?ie=UTF8&tag=javadesignpat-20&creative=9325&linkCode=as2&creativeASIN=1449358454&linkId=475c18363e350630cc0b39ab681b2687)

View File

@ -1,11 +0,0 @@
version: '3.7'
services:
mongodb_container:
image: mongo:latest
environment:
MONGO_INITDB_ROOT_USERNAME: root
MONGO_INITDB_ROOT_PASSWORD: rootpassword
ports:
- 27017:27017
volumes:
- ./mongo-data/:/data/db

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@ -1,4 +1,4 @@
<?xml version="1.0" encoding="UTF-8"?> <?xml version="1.0"?>
<!-- <!--
The MIT License The MIT License
@ -23,12 +23,13 @@
THE SOFTWARE. THE SOFTWARE.
--> -->
<project xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd"> <project xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd" xmlns="http://maven.apache.org/POM/4.0.0"
xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance">
<modelVersion>4.0.0</modelVersion> <modelVersion>4.0.0</modelVersion>
<parent> <parent>
<groupId>com.iluwatar</groupId> <groupId>com.iluwatar</groupId>
<artifactId>java-design-patterns</artifactId> <artifactId>java-design-patterns</artifactId>
<version>1.26.0-SNAPSHOT</version> <version>1.24.0-SNAPSHOT</version>
</parent> </parent>
<artifactId>caching</artifactId> <artifactId>caching</artifactId>
<dependencies> <dependencies>
@ -38,14 +39,19 @@
<scope>test</scope> <scope>test</scope>
</dependency> </dependency>
<dependency> <dependency>
<groupId>org.mockito</groupId> <groupId>org.mongodb</groupId>
<artifactId>mockito-all</artifactId> <artifactId>mongodb-driver</artifactId>
<version>1.10.19</version> <version>3.12.1</version>
<scope>test</scope>
</dependency> </dependency>
<dependency> <dependency>
<groupId>org.mongodb</groupId> <groupId>org.mongodb</groupId>
<artifactId>mongo-java-driver</artifactId> <artifactId>mongodb-driver-core</artifactId>
<version>3.0.4</version>
</dependency>
<dependency>
<groupId>org.mongodb</groupId>
<artifactId>bson</artifactId>
<version>3.0.4</version>
</dependency> </dependency>
</dependencies> </dependencies>
<!-- <!--

View File

@ -1,62 +1,58 @@
/*
* The MIT License
* Copyright © 2014-2021 Ilkka Seppälä
*
* Permission is hereby granted, free of charge, to any person obtaining a copy
* of this software and associated documentation files (the "Software"), to deal
* in the Software without restriction, including without limitation the rights
* to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
* copies of the Software, and to permit persons to whom the Software is
* furnished to do so, subject to the following conditions:
*
* The above copyright notice and this permission notice shall be included in
* all copies or substantial portions of the Software.
*
* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
* IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
* FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
* AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
* LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
* OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
* THE SOFTWARE.
*/
package com.iluwatar.caching; package com.iluwatar.caching;
import com.iluwatar.caching.database.DbManager;
import com.iluwatar.caching.database.DbManagerFactory;
import lombok.extern.slf4j.Slf4j; import lombok.extern.slf4j.Slf4j;
/** /**
* The Caching pattern describes how to avoid expensive re-acquisition of * The Caching pattern describes how to avoid expensive re-acquisition of resources by not releasing
* resources by not releasing the resources immediately after their use. * the resources immediately after their use. The resources retain their identity, are kept in some
* The resources retain their identity, are kept in some fast-access storage, * fast-access storage, and are re-used to avoid having to acquire them again. There are four main
* and are re-used to avoid having to acquire them again. There are four main * caching strategies/techniques in this pattern; each with their own pros and cons. They are;
* caching strategies/techniques in this pattern; each with their own pros and * <code>write-through</code> which writes data to the cache and DB in a single transaction,
* cons. They are <code>write-through</code> which writes data to the cache and * <code>write-around</code> which writes data immediately into the DB instead of the cache,
* DB in a single transaction, <code>write-around</code> which writes data * <code>write-behind</code> which writes data into the cache initially whilst the data is only
* immediately into the DB instead of the cache, <code>write-behind</code> * written into the DB when the cache is full, and <code>cache-aside</code> which pushes the
* which writes data into the cache initially whilst the data is only * responsibility of keeping the data synchronized in both data sources to the application itself.
* written into the DB when the cache is full, and <code>cache-aside</code> * The <code>read-through</code> strategy is also included in the mentioned four strategies --
* which pushes the responsibility of keeping the data synchronized in both * returns data from the cache to the caller <b>if</b> it exists <b>else</b> queries from DB and
* data sources to the application itself. The <code>read-through</code> * stores it into the cache for future use. These strategies determine when the data in the cache
* strategy is also included in the mentioned four strategies -- * should be written back to the backing store (i.e. Database) and help keep both data sources
* returns data from the cache to the caller <b>if</b> it exists <b>else</b> * synchronized/up-to-date. This pattern can improve performance and also helps to maintain
* queries from DB and stores it into the cache for future use. These strategies * consistency between data held in the cache and the data in the underlying data store.
* determine when the data in the cache should be written back to the backing
* store (i.e. Database) and help keep both data sources
* synchronized/up-to-date. This pattern can improve performance and also helps
* to maintainconsistency between data held in the cache and the data in
* the underlying data store.
* *
* <p>In this example, the user account ({@link UserAccount}) entity is used * <p>In this example, the user account ({@link UserAccount}) entity is used as the underlying
* as the underlying application data. The cache itself is implemented as an * application data. The cache itself is implemented as an internal (Java) data structure. It adopts
* internal (Java) data structure. It adopts a Least-Recently-Used (LRU) * a Least-Recently-Used (LRU) strategy for evicting data from itself when its full. The four
* strategy for evicting data from itself when its full. The four * strategies are individually tested. The testing of the cache is restricted towards saving and
* strategies are individually tested. The testing of the cache is restricted * querying of user accounts from the underlying data store ( {@link DbManager}). The main class (
* towards saving and querying of user accounts from the * {@link App} is not aware of the underlying mechanics of the application (i.e. save and query) and
* underlying data store( {@link DbManager}). The main class ( {@link App} * whether the data is coming from the cache or the DB (i.e. separation of concern). The AppManager
* is not aware of the underlying mechanics of the application * ({@link AppManager}) handles the transaction of data to-and-from the underlying data store
* (i.e. save and query) and whether the data is coming from the cache or the * (depending on the preferred caching policy/strategy).
* DB (i.e. separation of concern). The AppManager ({@link AppManager}) handles
* the transaction of data to-and-from the underlying data store (depending on
* the preferred caching policy/strategy).
* <p> * <p>
* <i>{@literal App --> AppManager --> CacheStore/LRUCache/CachingPolicy --> * <i>{@literal App --> AppManager --> CacheStore/LRUCache/CachingPolicy --> DBManager} </i>
* DBManager} </i>
* </p>
*
* <p>
* There are 2 ways to launch the application.
* - to use "in Memory" database.
* - to use the MongoDb as a database
*
* To run the application with "in Memory" database, just launch it without parameters
* Example: 'java -jar app.jar'
*
* To run the application with MongoDb you need to be installed the MongoDb
* in your system, or to launch it in the docker container.
* You may launch docker container from the root of current module with command:
* 'docker-compose up'
* Then you can start the application with parameter --mongo
* Example: 'java -jar app.jar --mongo'
* </p> * </p>
* *
* @see CacheStore * @see CacheStore
@ -65,67 +61,23 @@ import lombok.extern.slf4j.Slf4j;
*/ */
@Slf4j @Slf4j
public class App { public class App {
/**
* Constant parameter name to use mongoDB.
*/
private static final String USE_MONGO_DB = "--mongo";
/**
* Application manager.
*/
private final AppManager appManager;
/**
* Constructor of current App.
*
* @param isMongo boolean
*/
public App(final boolean isMongo) {
DbManager dbManager = DbManagerFactory.initDb(isMongo);
appManager = new AppManager(dbManager);
appManager.initDb();
}
/** /**
* Program entry point. * Program entry point.
* *
* @param args command line args * @param args command line args
*/ */
public static void main(final String[] args) { public static void main(String[] args) {
// VirtualDB (instead of MongoDB) was used in running the JUnit tests AppManager.initDb(false); // VirtualDB (instead of MongoDB) was used in running the JUnit tests
// and the App class to avoid Maven compilation errors. Set flag to // and the App class to avoid Maven compilation errors. Set flag to
// true to run the tests with MongoDB (provided that MongoDB is // true to run the tests with MongoDB (provided that MongoDB is
// installed and socket connection is open). // installed and socket connection is open).
boolean isDbMongo = isDbMongo(args); AppManager.initCacheCapacity(3);
if (isDbMongo) { var app = new App();
LOGGER.info("Using the Mongo database engine to run the application.");
} else {
LOGGER.info("Using the 'in Memory' database to run the application.");
}
App app = new App(isDbMongo);
app.useReadAndWriteThroughStrategy(); app.useReadAndWriteThroughStrategy();
String splitLine = "==============================================";
LOGGER.info(splitLine);
app.useReadThroughAndWriteAroundStrategy(); app.useReadThroughAndWriteAroundStrategy();
LOGGER.info(splitLine);
app.useReadThroughAndWriteBehindStrategy(); app.useReadThroughAndWriteBehindStrategy();
LOGGER.info(splitLine);
app.useCacheAsideStategy(); app.useCacheAsideStategy();
LOGGER.info(splitLine);
}
/**
* Check the input parameters. if
*
* @param args input params
* @return true if there is "--mongo" parameter in arguments
*/
private static boolean isDbMongo(final String[] args) {
for (String arg : args) {
if (arg.equals(USE_MONGO_DB)) {
return true;
}
}
return false;
} }
/** /**
@ -133,14 +85,14 @@ public class App {
*/ */
public void useReadAndWriteThroughStrategy() { public void useReadAndWriteThroughStrategy() {
LOGGER.info("# CachingPolicy.THROUGH"); LOGGER.info("# CachingPolicy.THROUGH");
appManager.initCachingPolicy(CachingPolicy.THROUGH); AppManager.initCachingPolicy(CachingPolicy.THROUGH);
var userAccount1 = new UserAccount("001", "John", "He is a boy."); var userAccount1 = new UserAccount("001", "John", "He is a boy.");
appManager.save(userAccount1); AppManager.save(userAccount1);
LOGGER.info(appManager.printCacheContent()); LOGGER.info(AppManager.printCacheContent());
appManager.find("001"); AppManager.find("001");
appManager.find("001"); AppManager.find("001");
} }
/** /**
@ -148,21 +100,21 @@ public class App {
*/ */
public void useReadThroughAndWriteAroundStrategy() { public void useReadThroughAndWriteAroundStrategy() {
LOGGER.info("# CachingPolicy.AROUND"); LOGGER.info("# CachingPolicy.AROUND");
appManager.initCachingPolicy(CachingPolicy.AROUND); AppManager.initCachingPolicy(CachingPolicy.AROUND);
var userAccount2 = new UserAccount("002", "Jane", "She is a girl."); var userAccount2 = new UserAccount("002", "Jane", "She is a girl.");
appManager.save(userAccount2); AppManager.save(userAccount2);
LOGGER.info(appManager.printCacheContent()); LOGGER.info(AppManager.printCacheContent());
appManager.find("002"); AppManager.find("002");
LOGGER.info(appManager.printCacheContent()); LOGGER.info(AppManager.printCacheContent());
userAccount2 = appManager.find("002"); userAccount2 = AppManager.find("002");
userAccount2.setUserName("Jane G."); userAccount2.setUserName("Jane G.");
appManager.save(userAccount2); AppManager.save(userAccount2);
LOGGER.info(appManager.printCacheContent()); LOGGER.info(AppManager.printCacheContent());
appManager.find("002"); AppManager.find("002");
LOGGER.info(appManager.printCacheContent()); LOGGER.info(AppManager.printCacheContent());
appManager.find("002"); AppManager.find("002");
} }
/** /**
@ -170,31 +122,23 @@ public class App {
*/ */
public void useReadThroughAndWriteBehindStrategy() { public void useReadThroughAndWriteBehindStrategy() {
LOGGER.info("# CachingPolicy.BEHIND"); LOGGER.info("# CachingPolicy.BEHIND");
appManager.initCachingPolicy(CachingPolicy.BEHIND); AppManager.initCachingPolicy(CachingPolicy.BEHIND);
var userAccount3 = new UserAccount("003", var userAccount3 = new UserAccount("003", "Adam", "He likes food.");
"Adam", var userAccount4 = new UserAccount("004", "Rita", "She hates cats.");
"He likes food."); var userAccount5 = new UserAccount("005", "Isaac", "He is allergic to mustard.");
var userAccount4 = new UserAccount("004",
"Rita",
"She hates cats.");
var userAccount5 = new UserAccount("005",
"Isaac",
"He is allergic to mustard.");
appManager.save(userAccount3); AppManager.save(userAccount3);
appManager.save(userAccount4); AppManager.save(userAccount4);
appManager.save(userAccount5); AppManager.save(userAccount5);
LOGGER.info(appManager.printCacheContent()); LOGGER.info(AppManager.printCacheContent());
appManager.find("003"); AppManager.find("003");
LOGGER.info(appManager.printCacheContent()); LOGGER.info(AppManager.printCacheContent());
UserAccount userAccount6 = new UserAccount("006", UserAccount userAccount6 = new UserAccount("006", "Yasha", "She is an only child.");
"Yasha", AppManager.save(userAccount6);
"She is an only child."); LOGGER.info(AppManager.printCacheContent());
appManager.save(userAccount6); AppManager.find("004");
LOGGER.info(appManager.printCacheContent()); LOGGER.info(AppManager.printCacheContent());
appManager.find("004");
LOGGER.info(appManager.printCacheContent());
} }
/** /**
@ -202,26 +146,20 @@ public class App {
*/ */
public void useCacheAsideStategy() { public void useCacheAsideStategy() {
LOGGER.info("# CachingPolicy.ASIDE"); LOGGER.info("# CachingPolicy.ASIDE");
appManager.initCachingPolicy(CachingPolicy.ASIDE); AppManager.initCachingPolicy(CachingPolicy.ASIDE);
LOGGER.info(appManager.printCacheContent()); LOGGER.info(AppManager.printCacheContent());
var userAccount3 = new UserAccount("003", var userAccount3 = new UserAccount("003", "Adam", "He likes food.");
"Adam", var userAccount4 = new UserAccount("004", "Rita", "She hates cats.");
"He likes food."); var userAccount5 = new UserAccount("005", "Isaac", "He is allergic to mustard.");
var userAccount4 = new UserAccount("004", AppManager.save(userAccount3);
"Rita", AppManager.save(userAccount4);
"She hates cats."); AppManager.save(userAccount5);
var userAccount5 = new UserAccount("005",
"Isaac",
"He is allergic to mustard.");
appManager.save(userAccount3);
appManager.save(userAccount4);
appManager.save(userAccount5);
LOGGER.info(appManager.printCacheContent()); LOGGER.info(AppManager.printCacheContent());
appManager.find("003"); AppManager.find("003");
LOGGER.info(appManager.printCacheContent()); LOGGER.info(AppManager.printCacheContent());
appManager.find("004"); AppManager.find("004");
LOGGER.info(appManager.printCacheContent()); LOGGER.info(AppManager.printCacheContent());
} }
} }

View File

@ -23,80 +23,63 @@
package com.iluwatar.caching; package com.iluwatar.caching;
import com.iluwatar.caching.database.DbManager; import java.text.ParseException;
import java.util.Optional; import java.util.Optional;
import lombok.extern.slf4j.Slf4j;
/** /**
* AppManager helps to bridge the gap in communication between the main class * AppManager helps to bridge the gap in communication between the main class and the application's
* and the application's back-end. DB connection is initialized through this * back-end. DB connection is initialized through this class. The chosen caching strategy/policy is
* class. The chosen caching strategy/policy is also initialized here. * also initialized here. Before the cache can be used, the size of the cache has to be set.
* Before the cache can be used, the size of the cache has to be set. * Depending on the chosen caching policy, AppManager will call the appropriate function in the
* Depending on the chosen caching policy, AppManager will call the * CacheStore class.
* appropriate function in the CacheStore class.
*/ */
@Slf4j public final class AppManager {
public class AppManager {
/**
* Caching Policy.
*/
private CachingPolicy cachingPolicy;
/**
* Database Manager.
*/
private final DbManager dbManager;
/**
* Cache Store.
*/
private final CacheStore cacheStore;
/** private static CachingPolicy cachingPolicy;
* Constructor.
* private AppManager() {
* @param newDbManager database manager
*/
public AppManager(final DbManager newDbManager) {
this.dbManager = newDbManager;
this.cacheStore = new CacheStore(newDbManager);
} }
/** /**
* Developer/Tester is able to choose whether the application should use * Developer/Tester is able to choose whether the application should use MongoDB as its underlying
* MongoDB as its underlying data storage or a simple Java data structure * data storage or a simple Java data structure to (temporarily) store the data/objects during
* to (temporarily) store the data/objects during runtime. * runtime.
*/ */
public void initDb() { public static void initDb(boolean useMongoDb) {
dbManager.connect(); if (useMongoDb) {
try {
DbManager.connect();
} catch (ParseException e) {
e.printStackTrace();
}
} else {
DbManager.createVirtualDb();
}
} }
/** /**
* Initialize caching policy. * Initialize caching policy.
*
* @param policy is a {@link CachingPolicy}
*/ */
public void initCachingPolicy(final CachingPolicy policy) { public static void initCachingPolicy(CachingPolicy policy) {
cachingPolicy = policy; cachingPolicy = policy;
if (cachingPolicy == CachingPolicy.BEHIND) { if (cachingPolicy == CachingPolicy.BEHIND) {
Runtime.getRuntime().addShutdownHook(new Thread(cacheStore::flushCache)); Runtime.getRuntime().addShutdownHook(new Thread(CacheStore::flushCache));
} }
cacheStore.clearCache(); CacheStore.clearCache();
}
public static void initCacheCapacity(int capacity) {
CacheStore.initCapacity(capacity);
} }
/** /**
* Find user account. * Find user account.
*
* @param userId String
* @return {@link UserAccount}
*/ */
public UserAccount find(final String userId) { public static UserAccount find(String userId) {
LOGGER.info("Trying to find {} in cache", userId); if (cachingPolicy == CachingPolicy.THROUGH || cachingPolicy == CachingPolicy.AROUND) {
if (cachingPolicy == CachingPolicy.THROUGH return CacheStore.readThrough(userId);
|| cachingPolicy == CachingPolicy.AROUND) {
return cacheStore.readThrough(userId);
} else if (cachingPolicy == CachingPolicy.BEHIND) { } else if (cachingPolicy == CachingPolicy.BEHIND) {
return cacheStore.readThroughWithWriteBackPolicy(userId); return CacheStore.readThroughWithWriteBackPolicy(userId);
} else if (cachingPolicy == CachingPolicy.ASIDE) { } else if (cachingPolicy == CachingPolicy.ASIDE) {
return findAside(userId); return findAside(userId);
} }
@ -105,55 +88,41 @@ public class AppManager {
/** /**
* Save user account. * Save user account.
*
* @param userAccount {@link UserAccount}
*/ */
public void save(final UserAccount userAccount) { public static void save(UserAccount userAccount) {
LOGGER.info("Save record!");
if (cachingPolicy == CachingPolicy.THROUGH) { if (cachingPolicy == CachingPolicy.THROUGH) {
cacheStore.writeThrough(userAccount); CacheStore.writeThrough(userAccount);
} else if (cachingPolicy == CachingPolicy.AROUND) { } else if (cachingPolicy == CachingPolicy.AROUND) {
cacheStore.writeAround(userAccount); CacheStore.writeAround(userAccount);
} else if (cachingPolicy == CachingPolicy.BEHIND) { } else if (cachingPolicy == CachingPolicy.BEHIND) {
cacheStore.writeBehind(userAccount); CacheStore.writeBehind(userAccount);
} else if (cachingPolicy == CachingPolicy.ASIDE) { } else if (cachingPolicy == CachingPolicy.ASIDE) {
saveAside(userAccount); saveAside(userAccount);
} }
} }
/** public static String printCacheContent() {
* Returns String. return CacheStore.print();
*
* @return String
*/
public String printCacheContent() {
return cacheStore.print();
} }
/** /**
* Cache-Aside save user account helper. * Cache-Aside save user account helper.
*
* @param userAccount {@link UserAccount}
*/ */
private void saveAside(final UserAccount userAccount) { private static void saveAside(UserAccount userAccount) {
dbManager.updateDb(userAccount); DbManager.updateDb(userAccount);
cacheStore.invalidate(userAccount.getUserId()); CacheStore.invalidate(userAccount.getUserId());
} }
/** /**
* Cache-Aside find user account helper. * Cache-Aside find user account helper.
*
* @param userId String
* @return {@link UserAccount}
*/ */
private UserAccount findAside(final String userId) { private static UserAccount findAside(String userId) {
return Optional.ofNullable(cacheStore.get(userId)) return Optional.ofNullable(CacheStore.get(userId))
.or(() -> { .or(() -> {
Optional<UserAccount> userAccount = Optional<UserAccount> userAccount = Optional.ofNullable(DbManager.readFromDb(userId));
Optional.ofNullable(dbManager.readFromDb(userId)); userAccount.ifPresent(account -> CacheStore.set(userId, account));
userAccount.ifPresent(account -> cacheStore.set(userId, account)); return userAccount;
return userAccount; })
}) .orElse(null);
.orElse(null);
} }
} }

View File

@ -23,11 +23,9 @@
package com.iluwatar.caching; package com.iluwatar.caching;
import com.iluwatar.caching.database.DbManager;
import java.util.List; import java.util.List;
import java.util.Optional; import java.util.Optional;
import java.util.stream.Collectors; import java.util.stream.Collectors;
import lombok.extern.slf4j.Slf4j; import lombok.extern.slf4j.Slf4j;
/** /**
@ -35,34 +33,16 @@ import lombok.extern.slf4j.Slf4j;
*/ */
@Slf4j @Slf4j
public class CacheStore { public class CacheStore {
/**
* Cache capacity.
*/
private static final int CAPACITY = 3;
/** private static LruCache cache;
* Lru cache see {@link LruCache}.
*/
private LruCache cache;
/**
* DbManager.
*/
private final DbManager dbManager;
/** private CacheStore() {
* Cache Store.
* @param dataBaseManager {@link DbManager}
*/
public CacheStore(final DbManager dataBaseManager) {
this.dbManager = dataBaseManager;
initCapacity(CAPACITY);
} }
/** /**
* Init cache capacity. * Init cache capacity.
* @param capacity int
*/ */
public void initCapacity(final int capacity) { public static void initCapacity(int capacity) {
if (cache == null) { if (cache == null) {
cache = new LruCache(capacity); cache = new LruCache(capacity);
} else { } else {
@ -72,64 +52,57 @@ public class CacheStore {
/** /**
* Get user account using read-through cache. * Get user account using read-through cache.
* @param userId {@link String}
* @return {@link UserAccount}
*/ */
public UserAccount readThrough(final String userId) { public static UserAccount readThrough(String userId) {
if (cache.contains(userId)) { if (cache.contains(userId)) {
LOGGER.info("# Found in Cache!"); LOGGER.info("# Cache Hit!");
return cache.get(userId); return cache.get(userId);
} }
LOGGER.info("# Not found in cache! Go to DB!!"); LOGGER.info("# Cache Miss!");
UserAccount userAccount = dbManager.readFromDb(userId); UserAccount userAccount = DbManager.readFromDb(userId);
cache.set(userId, userAccount); cache.set(userId, userAccount);
return userAccount; return userAccount;
} }
/** /**
* Get user account using write-through cache. * Get user account using write-through cache.
* @param userAccount {@link UserAccount}
*/ */
public void writeThrough(final UserAccount userAccount) { public static void writeThrough(UserAccount userAccount) {
if (cache.contains(userAccount.getUserId())) { if (cache.contains(userAccount.getUserId())) {
dbManager.updateDb(userAccount); DbManager.updateDb(userAccount);
} else { } else {
dbManager.writeToDb(userAccount); DbManager.writeToDb(userAccount);
} }
cache.set(userAccount.getUserId(), userAccount); cache.set(userAccount.getUserId(), userAccount);
} }
/** /**
* Get user account using write-around cache. * Get user account using write-around cache.
* @param userAccount {@link UserAccount}
*/ */
public void writeAround(final UserAccount userAccount) { public static void writeAround(UserAccount userAccount) {
if (cache.contains(userAccount.getUserId())) { if (cache.contains(userAccount.getUserId())) {
dbManager.updateDb(userAccount); DbManager.updateDb(userAccount);
// Cache data has been updated -- remove older cache.invalidate(userAccount.getUserId()); // Cache data has been updated -- remove older
cache.invalidate(userAccount.getUserId());
// version from cache. // version from cache.
} else { } else {
dbManager.writeToDb(userAccount); DbManager.writeToDb(userAccount);
} }
} }
/** /**
* Get user account using read-through cache with write-back policy. * Get user account using read-through cache with write-back policy.
* @param userId {@link String}
* @return {@link UserAccount}
*/ */
public UserAccount readThroughWithWriteBackPolicy(final String userId) { public static UserAccount readThroughWithWriteBackPolicy(String userId) {
if (cache.contains(userId)) { if (cache.contains(userId)) {
LOGGER.info("# Found in cache!"); LOGGER.info("# Cache Hit!");
return cache.get(userId); return cache.get(userId);
} }
LOGGER.info("# Not found in Cache!"); LOGGER.info("# Cache Miss!");
UserAccount userAccount = dbManager.readFromDb(userId); UserAccount userAccount = DbManager.readFromDb(userId);
if (cache.isFull()) { if (cache.isFull()) {
LOGGER.info("# Cache is FULL! Writing LRU data to DB..."); LOGGER.info("# Cache is FULL! Writing LRU data to DB...");
UserAccount toBeWrittenToDb = cache.getLruData(); UserAccount toBeWrittenToDb = cache.getLruData();
dbManager.upsertDb(toBeWrittenToDb); DbManager.upsertDb(toBeWrittenToDb);
} }
cache.set(userId, userAccount); cache.set(userId, userAccount);
return userAccount; return userAccount;
@ -137,13 +110,12 @@ public class CacheStore {
/** /**
* Set user account. * Set user account.
* @param userAccount {@link UserAccount}
*/ */
public void writeBehind(final UserAccount userAccount) { public static void writeBehind(UserAccount userAccount) {
if (cache.isFull() && !cache.contains(userAccount.getUserId())) { if (cache.isFull() && !cache.contains(userAccount.getUserId())) {
LOGGER.info("# Cache is FULL! Writing LRU data to DB..."); LOGGER.info("# Cache is FULL! Writing LRU data to DB...");
UserAccount toBeWrittenToDb = cache.getLruData(); UserAccount toBeWrittenToDb = cache.getLruData();
dbManager.upsertDb(toBeWrittenToDb); DbManager.upsertDb(toBeWrittenToDb);
} }
cache.set(userAccount.getUserId(), userAccount); cache.set(userAccount.getUserId(), userAccount);
} }
@ -151,7 +123,7 @@ public class CacheStore {
/** /**
* Clears cache. * Clears cache.
*/ */
public void clearCache() { public static void clearCache() {
if (cache != null) { if (cache != null) {
cache.clear(); cache.clear();
} }
@ -160,51 +132,44 @@ public class CacheStore {
/** /**
* Writes remaining content in the cache into the DB. * Writes remaining content in the cache into the DB.
*/ */
public void flushCache() { public static void flushCache() {
LOGGER.info("# flushCache..."); LOGGER.info("# flushCache...");
Optional.ofNullable(cache) Optional.ofNullable(cache)
.map(LruCache::getCacheDataInListForm) .map(LruCache::getCacheDataInListForm)
.orElse(List.of()) .orElse(List.of())
.forEach(dbManager::updateDb); .forEach(DbManager::updateDb);
dbManager.disconnect();
} }
/** /**
* Print user accounts. * Print user accounts.
* @return {@link String}
*/ */
public String print() { public static String print() {
return Optional.ofNullable(cache) return Optional.ofNullable(cache)
.map(LruCache::getCacheDataInListForm) .map(LruCache::getCacheDataInListForm)
.orElse(List.of()) .orElse(List.of())
.stream() .stream()
.map(userAccount -> userAccount.toString() + "\n") .map(userAccount -> userAccount.toString() + "\n")
.collect(Collectors.joining("", "\n--CACHE CONTENT--\n", "----")); .collect(Collectors.joining("", "\n--CACHE CONTENT--\n", "----\n"));
} }
/** /**
* Delegate to backing cache store. * Delegate to backing cache store.
* @param userId {@link String}
* @return {@link UserAccount}
*/ */
public UserAccount get(final String userId) { public static UserAccount get(String userId) {
return cache.get(userId); return cache.get(userId);
} }
/** /**
* Delegate to backing cache store. * Delegate to backing cache store.
* @param userId {@link String}
* @param userAccount {@link UserAccount}
*/ */
public void set(final String userId, final UserAccount userAccount) { public static void set(String userId, UserAccount userAccount) {
cache.set(userId, userAccount); cache.set(userId, userAccount);
} }
/** /**
* Delegate to backing cache store. * Delegate to backing cache store.
* @param userId {@link String}
*/ */
public void invalidate(final String userId) { public static void invalidate(String userId) {
cache.invalidate(userId); cache.invalidate(userId);
} }
} }

View File

@ -32,25 +32,10 @@ import lombok.Getter;
@AllArgsConstructor @AllArgsConstructor
@Getter @Getter
public enum CachingPolicy { public enum CachingPolicy {
/**
* Through.
*/
THROUGH("through"), THROUGH("through"),
/**
* AROUND.
*/
AROUND("around"), AROUND("around"),
/**
* BEHIND.
*/
BEHIND("behind"), BEHIND("behind"),
/**
* ASIDE.
*/
ASIDE("aside"); ASIDE("aside");
/**
* Policy value.
*/
private final String policy; private final String policy;
} }

View File

@ -0,0 +1,169 @@
/*
* The MIT License
* Copyright © 2014-2021 Ilkka Seppälä
*
* Permission is hereby granted, free of charge, to any person obtaining a copy
* of this software and associated documentation files (the "Software"), to deal
* in the Software without restriction, including without limitation the rights
* to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
* copies of the Software, and to permit persons to whom the Software is
* furnished to do so, subject to the following conditions:
*
* The above copyright notice and this permission notice shall be included in
* all copies or substantial portions of the Software.
*
* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
* IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
* FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
* AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
* LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
* OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
* THE SOFTWARE.
*/
package com.iluwatar.caching;
import com.iluwatar.caching.constants.CachingConstants;
import com.mongodb.MongoClient;
import com.mongodb.client.MongoDatabase;
import com.mongodb.client.model.UpdateOptions;
import java.text.ParseException;
import java.util.HashMap;
import java.util.Map;
import org.bson.Document;
/**
* <p>DBManager handles the communication with the underlying data store i.e. Database. It contains
* the implemented methods for querying, inserting, and updating data. MongoDB was used as the
* database for the application.</p>
*
* <p>Developer/Tester is able to choose whether the application should use MongoDB as its
* underlying data storage (connect()) or a simple Java data structure to (temporarily) store the
* data/objects during runtime (createVirtualDB()).</p>
*/
public final class DbManager {
private static MongoClient mongoClient;
private static MongoDatabase db;
private static boolean useMongoDB;
private static Map<String, UserAccount> virtualDB;
private DbManager() {
}
/**
* Create DB.
*/
public static void createVirtualDb() {
useMongoDB = false;
virtualDB = new HashMap<>();
}
/**
* Connect to DB.
*/
public static void connect() throws ParseException {
useMongoDB = true;
mongoClient = new MongoClient();
db = mongoClient.getDatabase("test");
}
/**
* Read user account from DB.
*/
public static UserAccount readFromDb(String userId) {
if (!useMongoDB) {
if (virtualDB.containsKey(userId)) {
return virtualDB.get(userId);
}
return null;
}
if (db == null) {
try {
connect();
} catch (ParseException e) {
e.printStackTrace();
}
}
var iterable = db
.getCollection(CachingConstants.USER_ACCOUNT)
.find(new Document(CachingConstants.USER_ID, userId));
if (iterable == null) {
return null;
}
Document doc = iterable.first();
String userName = doc.getString(CachingConstants.USER_NAME);
String appInfo = doc.getString(CachingConstants.ADD_INFO);
return new UserAccount(userId, userName, appInfo);
}
/**
* Write user account to DB.
*/
public static void writeToDb(UserAccount userAccount) {
if (!useMongoDB) {
virtualDB.put(userAccount.getUserId(), userAccount);
return;
}
if (db == null) {
try {
connect();
} catch (ParseException e) {
e.printStackTrace();
}
}
db.getCollection(CachingConstants.USER_ACCOUNT).insertOne(
new Document(CachingConstants.USER_ID, userAccount.getUserId())
.append(CachingConstants.USER_NAME, userAccount.getUserName())
.append(CachingConstants.ADD_INFO, userAccount.getAdditionalInfo())
);
}
/**
* Update DB.
*/
public static void updateDb(UserAccount userAccount) {
if (!useMongoDB) {
virtualDB.put(userAccount.getUserId(), userAccount);
return;
}
if (db == null) {
try {
connect();
} catch (ParseException e) {
e.printStackTrace();
}
}
db.getCollection(CachingConstants.USER_ACCOUNT).updateOne(
new Document(CachingConstants.USER_ID, userAccount.getUserId()),
new Document("$set", new Document(CachingConstants.USER_NAME, userAccount.getUserName())
.append(CachingConstants.ADD_INFO, userAccount.getAdditionalInfo())));
}
/**
* Insert data into DB if it does not exist. Else, update it.
*/
public static void upsertDb(UserAccount userAccount) {
if (!useMongoDB) {
virtualDB.put(userAccount.getUserId(), userAccount);
return;
}
if (db == null) {
try {
connect();
} catch (ParseException e) {
e.printStackTrace();
}
}
db.getCollection(CachingConstants.USER_ACCOUNT).updateOne(
new Document(CachingConstants.USER_ID, userAccount.getUserId()),
new Document("$set",
new Document(CachingConstants.USER_ID, userAccount.getUserId())
.append(CachingConstants.USER_NAME, userAccount.getUserName())
.append(CachingConstants.ADD_INFO, userAccount.getAdditionalInfo())
),
new UpdateOptions().upsert(true)
);
}
}

View File

@ -29,83 +29,41 @@ import java.util.List;
import java.util.Map; import java.util.Map;
import lombok.extern.slf4j.Slf4j; import lombok.extern.slf4j.Slf4j;
/** /**
* Data structure/implementation of the application's cache. The data structure * Data structure/implementation of the application's cache. The data structure consists of a hash
* consists of a hash table attached with a doubly linked-list. The linked-list * table attached with a doubly linked-list. The linked-list helps in capturing and maintaining the
* helps in capturing and maintaining the LRU data in the cache. When a data is * LRU data in the cache. When a data is queried (from the cache), added (to the cache), or updated,
* queried (from the cache), added (to the cache), or updated, the data is * the data is moved to the front of the list to depict itself as the most-recently-used data. The
* moved to the front of the list to depict itself as the most-recently-used * LRU data is always at the end of the list.
* data. The LRU data is always at the end of the list.
*/ */
@Slf4j @Slf4j
public class LruCache { public class LruCache {
/**
* Static class Node.
*/
static class Node {
/**
* user id.
*/
private final String userId;
/**
* User Account.
*/
private UserAccount userAccount;
/**
* previous.
*/
private Node previous;
/**
* next.
*/
private Node next;
/** static class Node {
* Node definition. String userId;
* UserAccount userAccount;
* @param id String Node previous;
* @param account {@link UserAccount} Node next;
*/
Node(final String id, final UserAccount account) { public Node(String userId, UserAccount userAccount) {
this.userId = id; this.userId = userId;
this.userAccount = account; this.userAccount = userAccount;
} }
} }
/** int capacity;
* Capacity of Cache. Map<String, Node> cache = new HashMap<>();
*/ Node head;
private int capacity; Node end;
/**
* Cache {@link HashMap}.
*/
private Map<String, Node> cache = new HashMap<>();
/**
* Head.
*/
private Node head;
/**
* End.
*/
private Node end;
/** public LruCache(int capacity) {
* Constructor. this.capacity = capacity;
*
* @param cap Integer.
*/
public LruCache(final int cap) {
this.capacity = cap;
} }
/** /**
* Get user account. * Get user account.
*
* @param userId String
* @return {@link UserAccount}
*/ */
public UserAccount get(final String userId) { public UserAccount get(String userId) {
if (cache.containsKey(userId)) { if (cache.containsKey(userId)) {
var node = cache.get(userId); var node = cache.get(userId);
remove(node); remove(node);
@ -117,10 +75,8 @@ public class LruCache {
/** /**
* Remove node from linked list. * Remove node from linked list.
*
* @param node {@link Node}
*/ */
public void remove(final Node node) { public void remove(Node node) {
if (node.previous != null) { if (node.previous != null) {
node.previous.next = node.next; node.previous.next = node.next;
} else { } else {
@ -135,10 +91,8 @@ public class LruCache {
/** /**
* Move node to the front of the list. * Move node to the front of the list.
*
* @param node {@link Node}
*/ */
public void setHead(final Node node) { public void setHead(Node node) {
node.next = head; node.next = head;
node.previous = null; node.previous = null;
if (head != null) { if (head != null) {
@ -152,11 +106,8 @@ public class LruCache {
/** /**
* Set user account. * Set user account.
*
* @param userAccount {@link UserAccount}
* @param userId {@link String}
*/ */
public void set(final String userId, final UserAccount userAccount) { public void set(String userId, UserAccount userAccount) {
if (cache.containsKey(userId)) { if (cache.containsKey(userId)) {
var old = cache.get(userId); var old = cache.get(userId);
old.userAccount = userAccount; old.userAccount = userAccount;
@ -176,43 +127,25 @@ public class LruCache {
} }
} }
/** public boolean contains(String userId) {
* Check if Cache contains the userId.
*
* @param userId {@link String}
* @return boolean
*/
public boolean contains(final String userId) {
return cache.containsKey(userId); return cache.containsKey(userId);
} }
/** /**
* Invalidate cache for user. * Invalidate cache for user.
*
* @param userId {@link String}
*/ */
public void invalidate(final String userId) { public void invalidate(String userId) {
var toBeRemoved = cache.remove(userId); var toBeRemoved = cache.remove(userId);
if (toBeRemoved != null) { if (toBeRemoved != null) {
LOGGER.info("# {} has been updated! " LOGGER.info("# {} has been updated! Removing older version from cache...", userId);
+ "Removing older version from cache...", userId);
remove(toBeRemoved); remove(toBeRemoved);
} }
} }
/**
* Check if the cache is full.
* @return boolean
*/
public boolean isFull() { public boolean isFull() {
return cache.size() >= capacity; return cache.size() >= capacity;
} }
/**
* Get LRU data.
*
* @return {@link UserAccount}
*/
public UserAccount getLruData() { public UserAccount getLruData() {
return end.userAccount; return end.userAccount;
} }
@ -228,8 +161,6 @@ public class LruCache {
/** /**
* Returns cache data in list form. * Returns cache data in list form.
*
* @return {@link List}
*/ */
public List<UserAccount> getCacheDataInListForm() { public List<UserAccount> getCacheDataInListForm() {
var listOfCacheData = new ArrayList<UserAccount>(); var listOfCacheData = new ArrayList<UserAccount>();
@ -243,14 +174,10 @@ public class LruCache {
/** /**
* Set cache capacity. * Set cache capacity.
*
* @param newCapacity int
*/ */
public void setCapacity(final int newCapacity) { public void setCapacity(int newCapacity) {
if (capacity > newCapacity) { if (capacity > newCapacity) {
// Behavior can be modified to accommodate clear(); // Behavior can be modified to accommodate for decrease in cache size. For now, we'll
// for decrease in cache size. For now, we'll
clear();
// just clear the cache. // just clear the cache.
} else { } else {
this.capacity = newCapacity; this.capacity = newCapacity;

View File

@ -24,28 +24,19 @@
package com.iluwatar.caching; package com.iluwatar.caching;
import lombok.AllArgsConstructor; import lombok.AllArgsConstructor;
import lombok.Data; import lombok.Getter;
import lombok.EqualsAndHashCode; import lombok.Setter;
import lombok.ToString; import lombok.ToString;
/** /**
* Entity class (stored in cache and DB) used in the application. * Entity class (stored in cache and DB) used in the application.
*/ */
@Data @Setter
@Getter
@AllArgsConstructor @AllArgsConstructor
@ToString @ToString
@EqualsAndHashCode
public class UserAccount { public class UserAccount {
/**
* User Id.
*/
private String userId; private String userId;
/**
* User Name.
*/
private String userName; private String userName;
/**
* Additional Info.
*/
private String additionalInfo; private String additionalInfo;
} }

View File

@ -26,27 +26,11 @@ package com.iluwatar.caching.constants;
/** /**
* Constant class for defining constants. * Constant class for defining constants.
*/ */
public final class CachingConstants { public class CachingConstants {
/**
* User Account.
*/
public static final String USER_ACCOUNT = "user_accounts"; public static final String USER_ACCOUNT = "user_accounts";
/**
* User ID.
*/
public static final String USER_ID = "userID"; public static final String USER_ID = "userID";
/**
* User Name.
*/
public static final String USER_NAME = "userName"; public static final String USER_NAME = "userName";
/**
* Additional Info.
*/
public static final String ADD_INFO = "additionalInfo"; public static final String ADD_INFO = "additionalInfo";
/**
* Constructor.
*/
private CachingConstants() {
}
} }

View File

@ -1,4 +0,0 @@
/**
* Constants.
*/
package com.iluwatar.caching.constants;

View File

@ -1,52 +0,0 @@
package com.iluwatar.caching.database;
import com.iluwatar.caching.UserAccount;
/**
* <p>DBManager handles the communication with the underlying data store i.e.
* Database. It contains the implemented methods for querying, inserting,
* and updating data. MongoDB was used as the database for the application.</p>
*/
public interface DbManager {
/**
* Connect to DB.
*/
void connect();
/**
* Disconnect from DB.
*/
void disconnect();
/**
* Read from DB.
*
* @param userId {@link String}
* @return {@link UserAccount}
*/
UserAccount readFromDb(String userId);
/**
* Write to DB.
*
* @param userAccount {@link UserAccount}
* @return {@link UserAccount}
*/
UserAccount writeToDb(UserAccount userAccount);
/**
* Update record.
*
* @param userAccount {@link UserAccount}
* @return {@link UserAccount}
*/
UserAccount updateDb(UserAccount userAccount);
/**
* Update record or Insert if not exists.
*
* @param userAccount {@link UserAccount}
* @return {@link UserAccount}
*/
UserAccount upsertDb(UserAccount userAccount);
}

View File

@ -1,25 +0,0 @@
package com.iluwatar.caching.database;
/**
* Creates the database connection accroding the input parameter.
*/
public final class DbManagerFactory {
/**
* Private constructor.
*/
private DbManagerFactory() {
}
/**
* Init database.
*
* @param isMongo boolean
* @return {@link DbManager}
*/
public static DbManager initDb(final boolean isMongo) {
if (isMongo) {
return new MongoDb();
}
return new VirtualDb();
}
}

View File

@ -1,128 +0,0 @@
package com.iluwatar.caching.database;
import static com.iluwatar.caching.constants.CachingConstants.ADD_INFO;
import static com.iluwatar.caching.constants.CachingConstants.USER_ACCOUNT;
import static com.iluwatar.caching.constants.CachingConstants.USER_ID;
import static com.iluwatar.caching.constants.CachingConstants.USER_NAME;
import com.iluwatar.caching.UserAccount;
import com.iluwatar.caching.constants.CachingConstants;
import com.mongodb.MongoClient;
import com.mongodb.MongoClientOptions;
import com.mongodb.MongoCredential;
import com.mongodb.ServerAddress;
import com.mongodb.client.MongoDatabase;
import com.mongodb.client.model.UpdateOptions;
import java.util.List;
import lombok.extern.slf4j.Slf4j;
import org.bson.Document;
/**
* Implementation of DatabaseManager.
* implements base methods to work with MongoDb.
*/
@Slf4j
public class MongoDb implements DbManager {
private static final String DATABASE_NAME = "admin";
private static final String MONGO_USER = "root";
private static final String MONGO_PASSWORD = "rootpassword";
private MongoClient client;
private MongoDatabase db;
/**
* Connect to Db. Check th connection
*/
@Override
public void connect() {
MongoCredential mongoCredential = MongoCredential.createCredential(MONGO_USER,
DATABASE_NAME,
MONGO_PASSWORD.toCharArray());
MongoClientOptions options = MongoClientOptions.builder().build();
client = new MongoClient(new ServerAddress(), List.of(mongoCredential), options);
db = client.getDatabase(DATABASE_NAME);
}
@Override
public void disconnect() {
client.close();
}
/**
* Read data from DB.
*
* @param userId {@link String}
* @return {@link UserAccount}
*/
@Override
public UserAccount readFromDb(final String userId) {
var iterable = db
.getCollection(CachingConstants.USER_ACCOUNT)
.find(new Document(USER_ID, userId));
if (iterable.first() == null) {
return null;
}
Document doc = iterable.first();
if (doc != null) {
String userName = doc.getString(USER_NAME);
String appInfo = doc.getString(ADD_INFO);
return new UserAccount(userId, userName, appInfo);
} else {
return null;
}
}
/**
* Write data to DB.
*
* @param userAccount {@link UserAccount}
* @return {@link UserAccount}
*/
@Override
public UserAccount writeToDb(final UserAccount userAccount) {
db.getCollection(USER_ACCOUNT).insertOne(
new Document(USER_ID, userAccount.getUserId())
.append(USER_NAME, userAccount.getUserName())
.append(ADD_INFO, userAccount.getAdditionalInfo())
);
return userAccount;
}
/**
* Update DB.
*
* @param userAccount {@link UserAccount}
* @return {@link UserAccount}
*/
@Override
public UserAccount updateDb(final UserAccount userAccount) {
Document id = new Document(USER_ID, userAccount.getUserId());
Document dataSet = new Document(USER_NAME, userAccount.getUserName())
.append(ADD_INFO, userAccount.getAdditionalInfo());
db.getCollection(CachingConstants.USER_ACCOUNT)
.updateOne(id, new Document("$set", dataSet));
return userAccount;
}
/**
* Update data if exists.
*
* @param userAccount {@link UserAccount}
* @return {@link UserAccount}
*/
@Override
public UserAccount upsertDb(final UserAccount userAccount) {
String userId = userAccount.getUserId();
String userName = userAccount.getUserName();
String additionalInfo = userAccount.getAdditionalInfo();
db.getCollection(CachingConstants.USER_ACCOUNT).updateOne(
new Document(USER_ID, userId),
new Document("$set",
new Document(USER_ID, userId)
.append(USER_NAME, userName)
.append(ADD_INFO, additionalInfo)
),
new UpdateOptions().upsert(true)
);
return userAccount;
}
}

View File

@ -1,78 +0,0 @@
package com.iluwatar.caching.database;
import com.iluwatar.caching.UserAccount;
import java.util.HashMap;
import java.util.Map;
/**
* Implementation of DatabaseManager.
* implements base methods to work with hashMap as database.
*/
public class VirtualDb implements DbManager {
/**
* Virtual DataBase.
*/
private Map<String, UserAccount> db;
/**
* Creates new HashMap.
*/
@Override
public void connect() {
db = new HashMap<>();
}
@Override
public void disconnect() {
db = null;
}
/**
* Read from Db.
*
* @param userId {@link String}
* @return {@link UserAccount}
*/
@Override
public UserAccount readFromDb(final String userId) {
if (db.containsKey(userId)) {
return db.get(userId);
}
return null;
}
/**
* Write to DB.
*
* @param userAccount {@link UserAccount}
* @return {@link UserAccount}
*/
@Override
public UserAccount writeToDb(final UserAccount userAccount) {
db.put(userAccount.getUserId(), userAccount);
return userAccount;
}
/**
* Update reecord in DB.
*
* @param userAccount {@link UserAccount}
* @return {@link UserAccount}
*/
@Override
public UserAccount updateDb(final UserAccount userAccount) {
return writeToDb(userAccount);
}
/**
* Update.
*
* @param userAccount {@link UserAccount}
* @return {@link UserAccount}
*/
@Override
public UserAccount upsertDb(final UserAccount userAccount) {
return updateDb(userAccount);
}
}

View File

@ -1,4 +0,0 @@
/**
* Database classes.
*/
package com.iluwatar.caching.database;

View File

@ -1,20 +0,0 @@
/**
* The MIT License
* Copyright © 2014-2021 Ilkka Seppälä
* Permission is hereby granted, free of charge, to any person obtaining a copy
* of this software and associated documentation files (the "Software"), to deal
* in the Software without restriction, including without limitation the rights
* to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
* copies of the Software, and to permit persons to whom the Software is
* furnished to do so, subject to the following conditions:
* The above copyright notice and this permission notice shall be included in
* all copies or substantial portions of the Software.
* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
* IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
* FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
* AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
* LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
* OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
* THE SOFTWARE.
*/
package com.iluwatar.caching;

View File

@ -25,21 +25,25 @@ package com.iluwatar.caching;
import org.junit.jupiter.api.Test; import org.junit.jupiter.api.Test;
import java.io.IOException;
import static org.junit.jupiter.api.Assertions.assertDoesNotThrow; import static org.junit.jupiter.api.Assertions.assertDoesNotThrow;
/** /**
* Tests that Caching example runs without errors. * Tests that Caching example runs without errors.
*/ */
class AppTest { class AppTest {
/** /**
* Issue: Add at least one assertion to this test case. * Issue: Add at least one assertion to this test case.
* <p> *
* Solution: Inserted assertion to check whether the execution of the main method in {@link App} * Solution: Inserted assertion to check whether the execution of the main method in {@link App}
* throws an exception. * throws an exception.
*/ */
@Test @Test
void shouldExecuteApplicationWithoutException() { void shouldExecuteApplicationWithoutException() {
assertDoesNotThrow(() -> App.main(new String[]{})); assertDoesNotThrow(() -> App.main(new String[]{}));
} }
} }

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