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@ -16,17 +16,6 @@
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@ -24,9 +24,6 @@
# 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
# 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
on:
@ -36,34 +33,38 @@ on:
jobs:
# This Workflow Job will build this project and run Sonar analysis using JDK 11.0.3
build-and-analyze:
build:
name: Build and Run Sonar analysis on JDK 11.0.3
runs-on: ubuntu-20.04
steps:
- name: Checkout Code
uses: actions/checkout@v2
uses: actions/checkout@master
with:
# Disabling shallow clone for improving relevancy of SonarQube reporting
fetch-depth: 0
- name: Set up JDK 11.0.3
uses: actions/setup-java@v2
- name: Set up JDK 11
uses: actions/setup-java@master
with:
java-version: 11.0.3
distribution: 'zulu'
cache: 'maven'
java-version: 11
# Cache Sonar packages which as used to run anaylysis and collect metrics
- name: Cache SonarCloud packages
uses: actions/cache@v2
uses: actions/cache@master
with:
path: ~/.sonar/cache
key: ${{ 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
- name: Install xvfb
run: sudo apt-get install -y xvfb
@ -74,28 +75,3 @@ jobs:
# These two env variables are needed for sonar analysis
GITHUB_TOKEN: ${{ secrets.GITHUB_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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@ -34,22 +34,24 @@ on:
jobs:
build:
name: Build JDP
runs-on: ubuntu-20.04
strategy:
matrix:
java-version: [ 11.0.3, 11 ]
steps:
- name: Checkout Code
uses: actions/checkout@v2
uses: actions/checkout@master
- name: Set up JDK ${{ matrix.java-version }}
uses: actions/setup-java@v2
- name: Set up JDK 11
uses: actions/setup-java@master
with:
java-version: ${{ matrix.java-version }}
distribution: 'zulu'
cache: 'maven'
java-version: 11
- 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
- name: Install xvfb

1
.gitignore vendored
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@ -12,7 +12,6 @@ tmp/
local.properties
.loadpath
.recommenders
.DS_Store
####### Java annotation processor (APT) ########
.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
# distributed with this work for additional information
# regarding copyright ownership. The ASF licenses this file
# to you under the Apache License, Version 2.0 (the
# "License"); you may not use this file except in compliance
# with the License. You may obtain a copy of the License at
#
# http://www.apache.org/licenses/LICENSE-2.0
#
# Unless required by applicable law or agreed to in writing,
# software distributed under the License is distributed on an
# "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
# KIND, either express or implied. See the License for the
# specific language governing permissions and limitations
# under the License.
distributionUrl=https://repo.maven.apache.org/maven2/org/apache/maven/apache-maven/3.8.4/apache-maven-3.8.4-bin.zip
wrapperUrl=https://repo.maven.apache.org/maven2/org/apache/maven/wrapper/maven-wrapper/3.1.0/maven-wrapper-3.1.0.jar
#
# 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.
#
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)
Copyright © 2014-2021 Ilkka Seppälä
Copyright (c) 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
@ -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,
OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
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

163
README.md
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@ -6,22 +6,22 @@
![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)
[![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)
[![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](https://img.shields.io/badge/all_contributors-198-orange.svg?style=flat-square)](#contributors-)
[![All Contributors](https://img.shields.io/badge/all_contributors-155-orange.svg?style=flat-square)](#contributors-)
<!-- ALL-CONTRIBUTORS-BADGE:END -->
<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/>
# 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.
Design patterns can speed up the development process by providing tested, proven
@ -34,11 +34,11 @@ are familiar with the patterns.
# Getting started
This site showcases Java Design Patterns. The solutions have been developed by
experienced programmers and architects from the open-source community. The
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
experienced programmers and architects from the open source community. The
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 as
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
[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.
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
- 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 pattern categories, `Creational`, `Behavioral`, and others.
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.
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 developing them.
# How to contribute
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
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
you and answer your questions in the [Gitter chatroom](https://gitter.im/iluwatar/java-design-patterns).
# License
@ -77,26 +77,29 @@ This project is licensed under the terms of the MIT license.
<table>
<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="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/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="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>
<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://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="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/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>
<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="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>
</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/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>
@ -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/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>
</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://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="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>
<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/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://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>
<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="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://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/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>
<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://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>
</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://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>
@ -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://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>
</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/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="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>
<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="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/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>
<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="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="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://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>
<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="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>
</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/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>
@ -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/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>
</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/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://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>
<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/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/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>
<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/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://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="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>
<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://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>
</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="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>
@ -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/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>
</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://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://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>
<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://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/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>
<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/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://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://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://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>
</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="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://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/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>
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<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="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>
</tr>
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<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="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 +290,23 @@ 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/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>
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<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/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="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/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/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/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/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://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>
</table>

View File

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

View File

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

View File

@ -27,7 +27,8 @@ import com.iluwatar.abstractdocument.domain.Car;
import com.iluwatar.abstractdocument.domain.enums.Property;
import java.util.List;
import java.util.Map;
import lombok.extern.slf4j.Slf4j;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
/**
* The Abstract Document pattern enables handling additional, non-static properties. This pattern
@ -37,9 +38,10 @@ import lombok.extern.slf4j.Slf4j;
* <p>In Abstract Document pattern,({@link AbstractDocument}) fully implements {@link Document})
* interface. Traits are then defined to enable access to properties in usual, static way.
*/
@Slf4j
public class App {
private static final Logger LOGGER = LoggerFactory.getLogger(App.class);
/**
* Program entry point.
*

View File

@ -23,18 +23,19 @@
package com.iluwatar.abstractdocument;
import org.junit.jupiter.api.Test;
import static org.junit.jupiter.api.Assertions.assertEquals;
import static org.junit.jupiter.api.Assertions.assertNotNull;
import static org.junit.jupiter.api.Assertions.assertTrue;
import java.util.HashMap;
import java.util.List;
import java.util.Map;
import static org.junit.jupiter.api.Assertions.*;
import org.junit.jupiter.api.Test;
/**
* AbstractDocument test class
*/
class AbstractDocumentTest {
public class AbstractDocumentTest {
private static final String KEY = "key";
private static final String VALUE = "value";
@ -49,13 +50,13 @@ class AbstractDocumentTest {
private final DocumentImplementation document = new DocumentImplementation(new HashMap<>());
@Test
void shouldPutAndGetValue() {
public void shouldPutAndGetValue() {
document.put(KEY, VALUE);
assertEquals(VALUE, document.get(KEY));
}
@Test
void shouldRetrieveChildren() {
public void shouldRetrieveChildren() {
var children = List.of(Map.of(), Map.of());
document.put(KEY, children);
@ -66,14 +67,14 @@ class AbstractDocumentTest {
}
@Test
void shouldRetrieveEmptyStreamForNonExistingChildren() {
public void shouldRetrieveEmptyStreamForNonExistingChildren() {
var children = document.children(KEY, DocumentImplementation::new);
assertNotNull(children);
assertEquals(0, children.count());
}
@Test
void shouldIncludePropsInToString() {
public void shouldIncludePropsInToString() {
var props = Map.of(KEY, (Object) VALUE);
var document = new DocumentImplementation(props);
assertTrue(document.toString().contains(KEY));

View File

@ -23,20 +23,19 @@
package com.iluwatar.abstractdocument;
import static org.junit.jupiter.api.Assertions.assertEquals;
import com.iluwatar.abstractdocument.domain.Car;
import com.iluwatar.abstractdocument.domain.Part;
import com.iluwatar.abstractdocument.domain.enums.Property;
import org.junit.jupiter.api.Test;
import java.util.List;
import java.util.Map;
import static org.junit.jupiter.api.Assertions.assertEquals;
import org.junit.jupiter.api.Test;
/**
* Test for Part and Car
*/
class DomainTest {
public class DomainTest {
private static final String TEST_PART_TYPE = "test-part-type";
private static final String TEST_PART_MODEL = "test-part-model";
@ -46,7 +45,7 @@ class DomainTest {
private static final long TEST_CAR_PRICE = 1L;
@Test
void shouldConstructPart() {
public void shouldConstructPart() {
var partProperties = Map.of(
Property.TYPE.toString(), TEST_PART_TYPE,
Property.MODEL.toString(), TEST_PART_MODEL,
@ -59,7 +58,7 @@ class DomainTest {
}
@Test
void shouldConstructCar() {
public void shouldConstructCar() {
var carProperties = Map.of(
Property.MODEL.toString(), TEST_CAR_MODEL,
Property.PRICE.toString(), TEST_CAR_PRICE,

View File

@ -4,7 +4,6 @@ title: Abstract Factory
folder: abstract-factory
permalink: /patterns/abstract-factory/
categories: Creational
language: en
tags:
- Gang of Four
---
@ -20,9 +19,9 @@ objects without specifying their concrete classes.
## 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
@ -34,7 +33,7 @@ Wikipedia says
**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.
```java
@ -52,21 +51,21 @@ public interface Army {
// Elven implementations ->
public class ElfCastle implements Castle {
static final String DESCRIPTION = "This is the elven castle!";
static final String DESCRIPTION = "This is the Elven castle!";
@Override
public String getDescription() {
return DESCRIPTION;
}
}
public class ElfKing implements King {
static final String DESCRIPTION = "This is the elven king!";
static final String DESCRIPTION = "This is the Elven king!";
@Override
public String getDescription() {
return DESCRIPTION;
}
}
public class ElfArmy implements Army {
static final String DESCRIPTION = "This is the elven Army!";
static final String DESCRIPTION = "This is the Elven Army!";
@Override
public String getDescription() {
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
public interface KingdomFactory {
@ -87,43 +86,31 @@ public interface KingdomFactory {
}
public class ElfKingdomFactory implements KingdomFactory {
@Override
public Castle createCastle() {
return new ElfCastle();
}
@Override
public King createKing() {
return new ElfKing();
}
@Override
public Army createArmy() {
return new ElfArmy();
}
}
public class OrcKingdomFactory implements KingdomFactory {
@Override
public Castle createCastle() {
return new OrcCastle();
}
@Override
public King createKing() {
return new OrcKing();
}
@Override
public Army createArmy() {
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
var factory = new ElfKingdomFactory();
@ -139,13 +126,13 @@ army.getDescription();
Program output:
```java
This is the elven castle!
This is the elven king!
This is the elven Army!
This is the Elven castle!
This is the Elven king!
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`.
The client can use `FactoryMaker` to create the desired concrete factory which, in turn, will produce different concrete objects (derived from `Army`, `King`, `Castle`).
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 (Army, King, Castle).
In this example, we also used an enum to parameterize which type of kingdom factory the client will ask for.
```java
@ -191,8 +178,8 @@ public static void main(String[] args) {
Use the Abstract Factory pattern when
* 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 independent of how its products are created, composed and represented
* 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
* 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.
@ -208,13 +195,13 @@ Example use cases
* Unit test case writing becomes much easier
* 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.
* 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)

View File

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

View File

@ -23,7 +23,8 @@
package com.iluwatar.abstractfactory;
import lombok.extern.slf4j.Slf4j;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
/**
* The Abstract Factory pattern provides a way to encapsulate a group of individual factories that
@ -37,11 +38,12 @@ import lombok.extern.slf4j.Slf4j;
*
* <p>The essence of the Abstract Factory pattern is a factory interface ({@link KingdomFactory})
* 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
public class App implements Runnable {
private static Logger log = LoggerFactory.getLogger(App.class);
private final Kingdom kingdom = new Kingdom();
public Kingdom getKingdom() {
@ -60,17 +62,17 @@ public class App implements Runnable {
@Override
public void run() {
LOGGER.info("elf kingdom");
log.info("Elf Kingdom");
createKingdom(Kingdom.FactoryMaker.KingdomType.ELF);
LOGGER.info(kingdom.getArmy().getDescription());
LOGGER.info(kingdom.getCastle().getDescription());
LOGGER.info(kingdom.getKing().getDescription());
log.info(kingdom.getArmy().getDescription());
log.info(kingdom.getCastle().getDescription());
log.info(kingdom.getKing().getDescription());
LOGGER.info("orc kingdom");
log.info("Orc Kingdom");
createKingdom(Kingdom.FactoryMaker.KingdomType.ORC);
LOGGER.info(kingdom.getArmy().getDescription());
LOGGER.info(kingdom.getCastle().getDescription());
LOGGER.info(kingdom.getKing().getDescription());
log.info(kingdom.getArmy().getDescription());
log.info(kingdom.getCastle().getDescription());
log.info(kingdom.getKing().getDescription());
}
/**

View File

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

View File

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

View File

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

View File

@ -23,17 +23,36 @@
package com.iluwatar.abstractfactory;
import lombok.Getter;
import lombok.Setter;
@Getter
@Setter
public class Kingdom {
private King king;
private Castle castle;
private Army army;
public King getKing() {
return king;
}
public Castle getCastle() {
return castle;
}
public Army getArmy() {
return army;
}
public void setKing(King king) {
this.king = king;
}
public void setCastle(Castle castle) {
this.castle = castle;
}
public void setArmy(Army army) {
this.army = army;
}
/**
* The factory of kingdom factories.
*/

View File

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

View File

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

View File

@ -28,7 +28,7 @@ package com.iluwatar.abstractfactory;
*/
public class OrcKing implements King {
static final String DESCRIPTION = "This is the orc king!";
static final String DESCRIPTION = "This is the Orc king!";
@Override
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;
/**
* Tests for abstract factory.
* Test for abstract factory.
*/
class AbstractFactoryTest {
public class AbstractFactoryTest {
private final App app = new App();
@Test
void verifyKingCreation() {
public void king() {
app.createKingdom(Kingdom.FactoryMaker.KingdomType.ELF);
final var kingdom = app.getKingdom();
@ -51,7 +51,7 @@ class AbstractFactoryTest {
}
@Test
void verifyCastleCreation() {
public void castle() {
app.createKingdom(Kingdom.FactoryMaker.KingdomType.ELF);
final var kingdom = app.getKingdom();
@ -66,7 +66,7 @@ class AbstractFactoryTest {
}
@Test
void verifyArmyCreation() {
public void army() {
app.createKingdom(Kingdom.FactoryMaker.KingdomType.ELF);
final var kingdom = app.getKingdom();
@ -81,7 +81,7 @@ class AbstractFactoryTest {
}
@Test
void verifyElfKingdomCreation() {
public void createElfKingdom() {
app.createKingdom(Kingdom.FactoryMaker.KingdomType.ELF);
final var kingdom = app.getKingdom();
@ -97,7 +97,7 @@ class AbstractFactoryTest {
}
@Test
void verifyOrcKingdomCreation() {
public void createOrcKingdom() {
app.createKingdom(Kingdom.FactoryMaker.KingdomType.ORC);
final var kingdom = app.getKingdom();

View File

@ -28,13 +28,20 @@ import org.junit.jupiter.api.Test;
import static org.junit.jupiter.api.Assertions.assertDoesNotThrow;
/**
* Check whether the execution of the main method in {@link App} throws an exception.
* Tests that Abstract Factory example runs without errors.
*/
class AppTest {
/**
* 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.
*/
@Test
void shouldExecuteApplicationWithoutException() {
assertDoesNotThrow(() -> App.main(new String[]{}));
assertDoesNotThrow(() -> App.main(new String[]{}));
}
}

View File

@ -1,130 +0,0 @@
---
layout: pattern
title: Active Object
folder: active-object
permalink: /patterns/active-object/
categories: Concurrency
language: en
tags:
- Performance
---
## 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.
## Explanation
The class that implements the active object pattern will contain a self-synchronization mechanism without using 'synchronized' methods.
Real-world example
>The Orcs are known for their wildness and untameable soul. It seems like they have their own thread of control based on previous behavior.
To implement a creature that has its own thread of control mechanism and expose its API only and not the execution itself, we can use the Active Object pattern.
**Programmatic Example**
```java
public abstract class ActiveCreature{
private final Logger logger = LoggerFactory.getLogger(ActiveCreature.class.getName());
private BlockingQueue<Runnable> requests;
private String name;
private Thread thread;
public ActiveCreature(String name) {
this.name = name;
this.requests = new LinkedBlockingQueue<Runnable>();
thread = new Thread(new Runnable() {
@Override
public void run() {
while (true) {
try {
requests.take().run();
} catch (InterruptedException e) {
logger.error(e.getMessage());
}
}
}
}
);
thread.start();
}
public void eat() throws InterruptedException {
requests.put(new Runnable() {
@Override
public void run() {
logger.info("{} is eating!",name());
logger.info("{} has finished eating!",name());
}
}
);
}
public void roam() throws InterruptedException {
requests.put(new Runnable() {
@Override
public void run() {
logger.info("{} has started to roam the wastelands.",name());
}
}
);
}
public String name() {
return this.name;
}
}
```
We can see that any class that will extend the ActiveCreature class will have its own thread of control to invoke and execute methods.
For example, the Orc class:
```java
public class Orc extends ActiveCreature {
public Orc(String name) {
super(name);
}
}
```
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
public static void main(String[] args) {
var app = new App();
app.run();
}
@Override
public void run() {
ActiveCreature creature;
try {
for (int i = 0;i < creatures;i++) {
creature = new Orc(Orc.class.getSimpleName().toString() + i);
creature.eat();
creature.roam();
}
Thread.sleep(1000);
} catch (InterruptedException e) {
logger.error(e.getMessage());
}
Runtime.getRuntime().exit(1);
}
```
## 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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@ -1,25 +0,0 @@
@startuml
package com.iluwatar.activeobject {
abstract class ActiveCreature {
- logger : Logger
- name : String
- requests : BlockingQueue<Runnable>
- thread : Thread
+ ActiveCreature(name : String)
+ eat()
+ name() : String
+ roam()
}
class App {
- creatures : Integer
- logger : Logger
+ App()
+ main(args : String[]) {static}
+ run()
}
class Orc {
+ Orc(name : String)
}
}
Orc --|> ActiveCreature
@enduml

View File

@ -1,62 +0,0 @@
<?xml version="1.0" encoding="UTF-8"?>
<!--
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.
-->
<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">
<modelVersion>4.0.0</modelVersion>
<parent>
<groupId>com.iluwatar</groupId>
<artifactId>java-design-patterns</artifactId>
<version>1.26.0-SNAPSHOT</version>
</parent>
<artifactId>active-object</artifactId>
<dependencies>
<dependency>
<groupId>org.junit.jupiter</groupId>
<artifactId>junit-jupiter-engine</artifactId>
<scope>test</scope>
</dependency>
</dependencies>
<build>
<plugins>
<!-- Maven assembly plugin is invoked with default setting which we have
in parent pom and specifying the class having main method -->
<plugin>
<groupId>org.apache.maven.plugins</groupId>
<artifactId>maven-assembly-plugin</artifactId>
<executions>
<execution>
<configuration>
<archive>
<manifest>
<mainClass>com.iluwatar.activeobject.App</mainClass>
</manifest>
</archive>
</configuration>
</execution>
</executions>
</plugin>
</plugins>
</build>
</project>

View File

@ -1,118 +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.activeobject;
import java.util.concurrent.BlockingQueue;
import java.util.concurrent.LinkedBlockingQueue;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
/**
* ActiveCreature class is the base of the active object example.
* @author Noam Greenshtain
*
*/
public abstract class ActiveCreature {
private static final Logger logger = LoggerFactory.getLogger(ActiveCreature.class.getName());
private BlockingQueue<Runnable> requests;
private String name;
private Thread thread; // Thread of execution.
private int status; // status of the thread of execution.
/**
* Constructor and initialization.
*/
protected ActiveCreature(String name) {
this.name = name;
this.status = 0;
this.requests = new LinkedBlockingQueue<>();
thread = new Thread(() -> {
boolean infinite = true;
while (infinite) {
try {
requests.take().run();
} catch (InterruptedException e) {
if (this.status != 0) {
logger.error("Thread was interrupted. --> {}", e.getMessage());
}
infinite = false;
Thread.currentThread().interrupt();
}
}
});
thread.start();
}
/**
* Eats the porridge.
* @throws InterruptedException due to firing a new Runnable.
*/
public void eat() throws InterruptedException {
requests.put(() -> {
logger.info("{} is eating!",name());
logger.info("{} has finished eating!",name());
});
}
/**
* Roam the wastelands.
* @throws InterruptedException due to firing a new Runnable.
*/
public void roam() throws InterruptedException {
requests.put(() ->
logger.info("{} has started to roam in the wastelands.",name())
);
}
/**
* Returns the name of the creature.
* @return the name of the creature.
*/
public String name() {
return this.name;
}
/**
* Kills the thread of execution.
* @param status of the thread of execution. 0 == OK, the rest is logging an error.
*/
public void kill(int status) {
this.status = status;
this.thread.interrupt();
}
/**
* Returns the status of the thread of execution.
* @return the status of the thread of execution.
*/
public int getStatus() {
return this.status;
}
}

View File

@ -1,75 +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.activeobject;
import java.util.ArrayList;
import java.util.List;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
/**
* The Active Object pattern helps to solve synchronization difficulties without using
* 'synchronized' methods. The active object will contain a thread-safe data structure
* (such as BlockingQueue) and use to synchronize method calls by moving the logic of the method
* into an invocator(usually a Runnable) and store it in the DSA.
*
* <p>In this example, we fire 20 threads to modify a value in the target class.
*/
public class App implements Runnable {
private static final Logger logger = LoggerFactory.getLogger(App.class.getName());
private static final int NUM_CREATURES = 3;
/**
* Program entry point.
*
* @param args command line arguments.
*/
public static void main(String[] args) {
var app = new App();
app.run();
}
@Override
public void run() {
List<ActiveCreature> creatures = new ArrayList<>();
try {
for (int i = 0;i < NUM_CREATURES;i++) {
creatures.add(new Orc(Orc.class.getSimpleName() + i));
creatures.get(i).eat();
creatures.get(i).roam();
}
Thread.sleep(1000);
} catch (InterruptedException e) {
logger.error(e.getMessage());
Thread.currentThread().interrupt();
} finally {
for (int i = 0;i < NUM_CREATURES;i++) {
creatures.get(i).kill(0);
}
}
}
}

View File

@ -1,37 +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.activeobject;
/**
* An implementation of the ActiveCreature class.
* @author Noam Greenshtain
*
*/
public class Orc extends ActiveCreature {
public Orc(String name) {
super(name);
}
}

View File

@ -1,42 +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.activeobject;
import static org.junit.jupiter.api.Assertions.assertEquals;
import org.junit.jupiter.api.Test;
class ActiveCreatureTest {
@Test
void executionTest() throws InterruptedException {
ActiveCreature orc = new Orc("orc1");
assertEquals("orc1",orc.name());
assertEquals(0,orc.getStatus());
orc.eat();
orc.roam();
orc.kill(0);
}
}

View File

@ -1,37 +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.activeobject;
import static org.junit.jupiter.api.Assertions.assertDoesNotThrow;
import org.junit.jupiter.api.Test;
class AppTest {
@Test
void shouldExecuteApplicationWithoutException() {
assertDoesNotThrow(() -> App.main(new String[]{}));
}
}

View File

@ -4,7 +4,6 @@ title: Acyclic Visitor
folder: acyclic-visitor
permalink: /patterns/acyclic-visitor/
categories: Behavioral
language: en
tags:
- 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 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
The good:

View File

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

View File

@ -23,15 +23,17 @@
package com.iluwatar.acyclicvisitor;
import lombok.extern.slf4j.Slf4j;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
/**
* ConfigureForDosVisitor class implements both zoom's and hayes' visit method for Dos
* manufacturer.
*/
@Slf4j
public class ConfigureForDosVisitor implements AllModemVisitor {
private static final Logger LOGGER = LoggerFactory.getLogger(ConfigureForDosVisitor.class);
@Override
public void visit(Hayes hayes) {
LOGGER.info(hayes + " used with Dos configurator.");

View File

@ -23,15 +23,17 @@
package com.iluwatar.acyclicvisitor;
import lombok.extern.slf4j.Slf4j;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
/**
* ConfigureForUnixVisitor class implements zoom's visit method for Unix manufacturer, unlike
* traditional visitor pattern, this class may selectively implement visit for other modems.
*/
@Slf4j
public class ConfigureForUnixVisitor implements ZoomVisitor {
private static final Logger LOGGER = LoggerFactory.getLogger(ConfigureForUnixVisitor.class);
@Override
public void visit(Zoom zoom) {
LOGGER.info(zoom + " used with Unix configurator.");

View File

@ -23,13 +23,15 @@
package com.iluwatar.acyclicvisitor;
import lombok.extern.slf4j.Slf4j;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
/**
* Hayes class implements its accept method.
*/
@Slf4j
public class Hayes implements Modem {
public class Hayes extends Modem {
private static final Logger LOGGER = LoggerFactory.getLogger(ConfigureForDosVisitor.class);
/**
* Accepts all visitors but honors only HayesVisitor.

View File

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

View File

@ -23,13 +23,15 @@
package com.iluwatar.acyclicvisitor;
import lombok.extern.slf4j.Slf4j;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
/**
* Zoom class implements its accept method.
*/
@Slf4j
public class Zoom implements Modem {
public class Zoom extends Modem {
private static final Logger LOGGER = LoggerFactory.getLogger(ConfigureForDosVisitor.class);
/**
* Accepts all visitors but honors only ZoomVisitor.

View File

@ -35,34 +35,34 @@ import uk.org.lidalia.slf4jtest.TestLoggerFactory;
/**
* ConfigureForDosVisitor test class
*/
class ConfigureForDosVisitorTest {
public class ConfigureForDosVisitorTest {
private final TestLogger logger = TestLoggerFactory.getTestLogger(ConfigureForDosVisitor.class);
@Test
void testVisitForZoom() {
public void testVisitForZoom() {
var conDos = new ConfigureForDosVisitor();
var zoom = new Zoom();
conDos.visit(zoom);
assertThat(logger.getLoggingEvents())
.extracting("level", "message")
.contains(tuple(INFO, zoom + " used with Dos configurator."));
}
@Test
void testVisitForHayes() {
public void testVisitForHayes() {
var conDos = new ConfigureForDosVisitor();
var hayes = new Hayes();
conDos.visit(hayes);
assertThat(logger.getLoggingEvents())
.extracting("level", "message")
.contains(tuple(INFO, hayes + " used with Dos configurator."));
}
@AfterEach
public void clearLoggers() {
TestLoggerFactory.clear();

View File

@ -23,34 +23,35 @@
package com.iluwatar.acyclicvisitor;
import org.junit.jupiter.api.AfterEach;
import org.junit.jupiter.api.Test;
import uk.org.lidalia.slf4jtest.TestLogger;
import uk.org.lidalia.slf4jtest.TestLoggerFactory;
import static org.assertj.core.api.Assertions.assertThat;
import static org.assertj.core.groups.Tuple.tuple;
import static uk.org.lidalia.slf4jext.Level.INFO;
import org.junit.jupiter.api.AfterEach;
import org.junit.jupiter.api.Test;
import uk.org.lidalia.slf4jtest.TestLogger;
import uk.org.lidalia.slf4jtest.TestLoggerFactory;
/**
* ConfigureForUnixVisitor test class
*/
class ConfigureForUnixVisitorTest {
public class ConfigureForUnixVisitorTest {
private static final TestLogger LOGGER = TestLoggerFactory.getTestLogger(ConfigureForUnixVisitor.class);
@AfterEach
public void clearLoggers() {
TestLoggerFactory.clear();
}
@Test
void testVisitForZoom() {
public void testVisitForZoom() {
var conUnix = new ConfigureForUnixVisitor();
var zoom = new Zoom();
conUnix.visit(zoom);
assertThat(LOGGER.getLoggingEvents())
.extracting("level", "message")
.contains(tuple(INFO, zoom + " used with Unix configurator."));

View File

@ -23,32 +23,34 @@
package com.iluwatar.acyclicvisitor;
import org.junit.jupiter.api.Test;
import static org.mockito.Matchers.eq;
import static org.mockito.Mockito.*;
import static org.mockito.Mockito.mock;
import static org.mockito.Mockito.verify;
import static org.mockito.Mockito.verifyZeroInteractions;
import org.junit.jupiter.api.Test;
/**
* Hayes test class
*/
class HayesTest {
public class HayesTest {
@Test
void testAcceptForDos() {
public void testAcceptForDos() {
var hayes = new Hayes();
var mockVisitor = mock(ConfigureForDosVisitor.class);
hayes.accept(mockVisitor);
verify((HayesVisitor) mockVisitor).visit(eq(hayes));
verify((HayesVisitor)mockVisitor).visit(eq(hayes));
}
@Test
void testAcceptForUnix() {
public void testAcceptForUnix() {
var hayes = new Hayes();
var mockVisitor = mock(ConfigureForUnixVisitor.class);
hayes.accept(mockVisitor);
verifyZeroInteractions(mockVisitor);
}
}

View File

@ -24,32 +24,32 @@
package com.iluwatar.acyclicvisitor;
import org.junit.jupiter.api.Test;
import static org.mockito.Matchers.eq;
import static org.mockito.Mockito.mock;
import static org.mockito.Mockito.verify;
import static org.mockito.Mockito.mock;
import org.junit.jupiter.api.Test;
/**
* Zoom test class
*/
class ZoomTest {
public class ZoomTest {
@Test
void testAcceptForDos() {
public void testAcceptForDos() {
var zoom = new Zoom();
var mockVisitor = mock(ConfigureForDosVisitor.class);
zoom.accept(mockVisitor);
verify((ZoomVisitor) mockVisitor).visit(eq(zoom));
verify((ZoomVisitor)mockVisitor).visit(eq(zoom));
}
@Test
void testAcceptForUnix() {
public void testAcceptForUnix() {
var zoom = new Zoom();
var mockVisitor = mock(ConfigureForUnixVisitor.class);
zoom.accept(mockVisitor);
verify((ZoomVisitor) mockVisitor).visit(eq(zoom));
verify((ZoomVisitor)mockVisitor).visit(eq(zoom));
}
}

View File

@ -4,7 +4,6 @@ title: Adapter
folder: adapter
permalink: /patterns/adapter/
categories: Structural
language: en
tags:
- Gang of Four
---
@ -18,10 +17,10 @@ couldn't otherwise because of incompatible interfaces.
## 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.
> 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.
> 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 outlet.
> Yet another example would be a translator translating words spoken by one person to another
In plain words
@ -36,15 +35,15 @@ Wikipedia says
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
public interface RowingBoat {
void row();
}
@Slf4j
public class FishingBoat {
private static final Logger LOGGER = LoggerFactory.getLogger(FishingBoat.class);
public void sail() {
LOGGER.info("The fishing boat is sailing");
}
@ -68,12 +67,13 @@ 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
@Slf4j
public class FishingBoatAdapter implements RowingBoat {
private static final Logger LOGGER = LoggerFactory.getLogger(FishingBoatAdapter.class);
private final FishingBoat boat;
public FishingBoatAdapter() {
@ -100,31 +100,25 @@ captain.row();
## Applicability
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 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.
* 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.
* 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 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.
## Tutorials
* [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
## Consequences:
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.
* 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.
* 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.
* introduces only one object, and no additional pointer indirection is needed to get to the adaptee.
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.
* 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.
* 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 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.Collections#list()](https://docs.oracle.com/javase/8/docs/api/java/util/Collections.html#list-java.util.Enumeration-)

View File

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

View File

@ -23,20 +23,24 @@
package com.iluwatar.adapter;
import lombok.AllArgsConstructor;
import lombok.NoArgsConstructor;
import lombok.Setter;
/**
* The Captain uses {@link RowingBoat} to sail. <br> This is the client in the pattern.
*/
@Setter
@NoArgsConstructor
@AllArgsConstructor
public final class Captain {
private RowingBoat rowingBoat;
public Captain() {
}
public Captain(final RowingBoat boat) {
this.rowingBoat = boat;
}
void setRowingBoat(final RowingBoat boat) {
this.rowingBoat = boat;
}
void row() {
rowingBoat.row();
}

View File

@ -23,15 +23,18 @@
package com.iluwatar.adapter;
import lombok.extern.slf4j.Slf4j;
import static org.slf4j.LoggerFactory.getLogger;
import org.slf4j.Logger;
/**
* Device class (adaptee in the pattern). We want to reuse this class. Fishing boat moves by
* sailing.
*/
@Slf4j
final class FishingBoat {
private static final Logger LOGGER = getLogger(FishingBoat.class);
void sail() {
LOGGER.info("The fishing boat is sailing");
}

View File

@ -29,7 +29,11 @@ package com.iluwatar.adapter;
*/
public class FishingBoatAdapter implements RowingBoat {
private final FishingBoat boat = new FishingBoat();
private final FishingBoat boat;
public FishingBoatAdapter() {
boat = new FishingBoat();
}
public final void row() {
boat.sail();

View File

@ -23,19 +23,18 @@
package com.iluwatar.adapter;
import org.junit.jupiter.api.BeforeEach;
import org.junit.jupiter.api.Test;
import java.util.HashMap;
import java.util.Map;
import static org.mockito.Mockito.spy;
import static org.mockito.Mockito.verify;
import java.util.HashMap;
import java.util.Map;
import org.junit.jupiter.api.BeforeEach;
import org.junit.jupiter.api.Test;
/**
* Tests for the adapter pattern.
* Test class
*/
class AdapterPatternTest {
public class AdapterPatternTest {
private Map<String, Object> beans;
@ -65,7 +64,7 @@ class AdapterPatternTest {
* by the client ({@link Captain} ).
*/
@Test
void testAdapter() {
public void testAdapter() {
var captain = (Captain) beans.get(ROWING_BEAN);
// when captain moves

View File

@ -33,7 +33,9 @@ import static org.junit.jupiter.api.Assertions.assertDoesNotThrow;
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.
*/

View File

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

View File

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

View File

@ -26,7 +26,8 @@ package com.iluwatar.aggregator.microservices;
import static java.util.Objects.requireNonNullElse;
import javax.annotation.Resource;
import org.springframework.web.bind.annotation.GetMapping;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.RequestMethod;
import org.springframework.web.bind.annotation.RestController;
/**
@ -36,18 +37,20 @@ import org.springframework.web.bind.annotation.RestController;
@RestController
public class Aggregator {
@Resource
private ProductInformationClient informationClient;
@Resource
private ProductInventoryClient inventoryClient;
/**
* Retrieves product data.
*
* @return a Product.
*/
@GetMapping("/product")
@RequestMapping(path = "/product", method = RequestMethod.GET)
public Product getProduct() {
var product = new Product();

View File

@ -23,14 +23,9 @@
package com.iluwatar.aggregator.microservices;
import lombok.Getter;
import lombok.Setter;
/**
* Encapsulates all the data for a Product that clients will request.
*/
@Getter
@Setter
public class Product {
/**
@ -44,4 +39,20 @@ public class Product {
*/
private int productInventories;
public String getTitle() {
return title;
}
public void setTitle(String title) {
this.title = title;
}
public int getProductInventories() {
return productInventories;
}
public void setProductInventories(int productInventories) {
this.productInventories = productInventories;
}
}

View File

@ -28,16 +28,18 @@ import java.net.URI;
import java.net.http.HttpClient;
import java.net.http.HttpRequest;
import java.net.http.HttpResponse;
import lombok.extern.slf4j.Slf4j;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
import org.springframework.stereotype.Component;
/**
* An adapter to communicate with information micro-service.
*/
@Slf4j
@Component
public class ProductInformationClientImpl implements ProductInformationClient {
private static final Logger LOGGER = LoggerFactory.getLogger(ProductInformationClientImpl.class);
@Override
public String getProductTitle() {
var request = HttpRequest.newBuilder()
@ -52,7 +54,6 @@ public class ProductInformationClientImpl implements ProductInformationClient {
LOGGER.error("IOException Occurred", ioe);
} catch (InterruptedException ie) {
LOGGER.error("InterruptedException Occurred", ie);
Thread.currentThread().interrupt();
}
return null;
}

View File

@ -28,16 +28,18 @@ import java.net.URI;
import java.net.http.HttpClient;
import java.net.http.HttpRequest;
import java.net.http.HttpResponse;
import lombok.extern.slf4j.Slf4j;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
import org.springframework.stereotype.Component;
/**
* An adapter to communicate with inventory micro-service.
*/
@Slf4j
@Component
public class ProductInventoryClientImpl implements ProductInventoryClient {
private static final Logger LOGGER = LoggerFactory.getLogger(ProductInventoryClientImpl.class);
@Override
public Integer getProductInventories() {
var response = "";
@ -54,7 +56,6 @@ public class ProductInventoryClientImpl implements ProductInventoryClient {
LOGGER.error("IOException Occurred", ioe);
} catch (InterruptedException ie) {
LOGGER.error("InterruptedException Occurred", ie);
Thread.currentThread().interrupt();
}
if ("".equalsIgnoreCase(response)) {
return null;

View File

@ -23,19 +23,19 @@
package com.iluwatar.aggregator.microservices;
import static org.junit.jupiter.api.Assertions.assertEquals;
import static org.mockito.Mockito.when;
import org.junit.jupiter.api.BeforeEach;
import org.junit.jupiter.api.Test;
import org.mockito.InjectMocks;
import org.mockito.Mock;
import org.mockito.MockitoAnnotations;
import static org.junit.jupiter.api.Assertions.assertEquals;
import static org.mockito.Mockito.when;
/**
* Test Aggregation of domain objects
*/
class AggregatorTest {
public class AggregatorTest {
@InjectMocks
private Aggregator aggregator;
@ -48,14 +48,14 @@ class AggregatorTest {
@BeforeEach
public void setup() {
MockitoAnnotations.openMocks(this);
MockitoAnnotations.initMocks(this);
}
/**
* Tests getting the data for a desktop client
*/
@Test
void testGetProduct() {
public void testGetProduct() {
var title = "The Product Title.";
var inventories = 5;

View File

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

View File

@ -23,7 +23,8 @@
package com.iluwatar.information.microservice;
import org.springframework.web.bind.annotation.GetMapping;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.RequestMethod;
import org.springframework.web.bind.annotation.RestController;
/**
@ -37,7 +38,7 @@ public class InformationController {
*
* @return product inventory.
*/
@GetMapping("/information")
@RequestMapping(value = "/information", method = RequestMethod.GET)
public String getProductTitle() {
return "The Product Title.";
}

View File

@ -23,17 +23,17 @@
package com.iluwatar.information.microservice;
import org.junit.jupiter.api.Test;
import static org.junit.jupiter.api.Assertions.assertEquals;
import org.junit.jupiter.api.Test;
/**
* Test for Information Rest Controller
*/
class InformationControllerTest {
public class InformationControllerTest {
@Test
void shouldGetProductTitle() {
public void shouldGetProductTitle() {
var infoController = new InformationController();
var title = infoController.getProductTitle();
assertEquals("The Product Title.", title);

View File

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

View File

@ -23,7 +23,8 @@
package com.iluwatar.inventory.microservice;
import org.springframework.web.bind.annotation.GetMapping;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.RequestMethod;
import org.springframework.web.bind.annotation.RestController;
/**
@ -37,7 +38,7 @@ public class InventoryController {
*
* @return product inventory.
*/
@GetMapping("/inventories")
@RequestMapping(value = "/inventories", method = RequestMethod.GET)
public int getProductInventories() {
return 5;
}

View File

@ -23,17 +23,16 @@
package com.iluwatar.inventory.microservice;
import org.junit.jupiter.api.Test;
import static org.junit.jupiter.api.Assertions.assertEquals;
import org.junit.jupiter.api.Test;
/**
* Test Inventory Rest Controller
*/
class InventoryControllerTest {
public class InventoryControllerTest {
@Test
void testGetProductInventories() {
public void testGetProductInventories() {
var inventoryController = new InventoryController();
var numberOfInventories = inventoryController.getProductInventories();
assertEquals(5, numberOfInventories);

View File

@ -23,18 +23,20 @@
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">
<parent>
<artifactId>java-design-patterns</artifactId>
<groupId>com.iluwatar</groupId>
<version>1.26.0-SNAPSHOT</version>
</parent>
<modelVersion>4.0.0</modelVersion>
<artifactId>aggregator-microservices</artifactId>
<packaging>pom</packaging>
<modules>
<module>information-microservice</module>
<module>aggregator-service</module>
<module>inventory-microservice</module>
</modules>
<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>
<artifactId>java-design-patterns</artifactId>
<groupId>com.iluwatar</groupId>
<version>1.24.0-SNAPSHOT</version>
</parent>
<modelVersion>4.0.0</modelVersion>
<artifactId>aggregator-microservices</artifactId>
<packaging>pom</packaging>
<modules>
<module>information-microservice</module>
<module>aggregator-service</module>
<module>inventory-microservice</module>
</modules>
</project>

View File

@ -4,7 +4,6 @@ title: Ambassador
folder: ambassador
permalink: /patterns/ambassador/
categories: Structural
language: en
tags:
- Decoupling
- Cloud distributed
@ -49,8 +48,9 @@ interface RemoteServiceInterface {
A remote services represented as a singleton.
```java
@Slf4j
public class RemoteService implements RemoteServiceInterface {
private static final Logger LOGGER = LoggerFactory.getLogger(RemoteService.class);
private static RemoteService service = null;
static synchronized RemoteService getRemoteService() {
@ -80,8 +80,9 @@ public class RemoteService implements RemoteServiceInterface {
A service ambassador adding additional features such as logging, latency checks
```java
@Slf4j
public class ServiceAmbassador implements RemoteServiceInterface {
private static final Logger LOGGER = LoggerFactory.getLogger(ServiceAmbassador.class);
private static final int RETRIES = 3;
private static final int DELAY_MS = 3000;
@ -131,8 +132,9 @@ public class ServiceAmbassador implements RemoteServiceInterface {
A client has a local service ambassador used to interact with the remote service:
```java
@Slf4j
public class Client {
private static final Logger LOGGER = LoggerFactory.getLogger(Client.class);
private final ServiceAmbassador serviceAmbassador = new ServiceAmbassador();
long useService(int value) {

View File

@ -23,38 +23,40 @@
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">
<parent>
<artifactId>java-design-patterns</artifactId>
<groupId>com.iluwatar</groupId>
<version>1.26.0-SNAPSHOT</version>
</parent>
<modelVersion>4.0.0</modelVersion>
<artifactId>ambassador</artifactId>
<dependencies>
<dependency>
<groupId>org.junit.jupiter</groupId>
<artifactId>junit-jupiter-engine</artifactId>
<scope>test</scope>
</dependency>
</dependencies>
<build>
<plugins>
<plugin>
<groupId>org.apache.maven.plugins</groupId>
<artifactId>maven-assembly-plugin</artifactId>
<executions>
<execution>
<configuration>
<archive>
<manifest>
<mainClass>com.iluwatar.ambassador.App</mainClass>
</manifest>
</archive>
</configuration>
</execution>
</executions>
</plugin>
</plugins>
</build>
<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>
<artifactId>java-design-patterns</artifactId>
<groupId>com.iluwatar</groupId>
<version>1.24.0-SNAPSHOT</version>
</parent>
<modelVersion>4.0.0</modelVersion>
<artifactId>ambassador</artifactId>
<dependencies>
<dependency>
<groupId>org.junit.jupiter</groupId>
<artifactId>junit-jupiter-engine</artifactId>
<scope>test</scope>
</dependency>
</dependencies>
<build>
<plugins>
<plugin>
<groupId>org.apache.maven.plugins</groupId>
<artifactId>maven-assembly-plugin</artifactId>
<executions>
<execution>
<configuration>
<archive>
<manifest>
<mainClass>com.iluwatar.ambassador.App</mainClass>
</manifest>
</archive>
</configuration>
</execution>
</executions>
</plugin>
</plugins>
</build>
</project>

View File

@ -23,19 +23,20 @@
package com.iluwatar.ambassador;
import lombok.extern.slf4j.Slf4j;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
/**
* A simple Client.
*/
@Slf4j
public class Client {
private static final Logger LOGGER = LoggerFactory.getLogger(Client.class);
private final ServiceAmbassador serviceAmbassador = new ServiceAmbassador();
long useService(int value) {
var result = serviceAmbassador.doRemoteFunction(value);
LOGGER.info("Service result: {}", result);
LOGGER.info("Service result: " + result);
return result;
}
}

View File

@ -26,14 +26,15 @@ package com.iluwatar.ambassador;
import static java.lang.Thread.sleep;
import com.iluwatar.ambassador.util.RandomProvider;
import lombok.extern.slf4j.Slf4j;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
/**
* A remote legacy application represented by a Singleton implementation.
*/
@Slf4j
public class RemoteService implements RemoteServiceInterface {
private static final int THRESHOLD = 200;
private static final Logger LOGGER = LoggerFactory.getLogger(RemoteService.class);
private static RemoteService service = null;
private final RandomProvider randomProvider;
@ -72,9 +73,8 @@ public class RemoteService implements RemoteServiceInterface {
sleep(waitTime);
} catch (InterruptedException e) {
LOGGER.error("Thread sleep state interrupted", e);
Thread.currentThread().interrupt();
}
return waitTime <= THRESHOLD ? value * 10
: RemoteServiceStatus.FAILURE.getRemoteServiceStatusValue();
: RemoteServiceStatus.FAILURE.getRemoteServiceStatusValue();
}
}

View File

@ -33,7 +33,8 @@ package com.iluwatar.ambassador;
*/
public enum RemoteServiceStatus {
FAILURE(-1);
FAILURE(-1)
;
private final long remoteServiceStatusValue;

View File

@ -26,16 +26,17 @@ package com.iluwatar.ambassador;
import static com.iluwatar.ambassador.RemoteServiceStatus.FAILURE;
import static java.lang.Thread.sleep;
import lombok.extern.slf4j.Slf4j;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
/**
* ServiceAmbassador provides an interface for a ({@link Client}) to access ({@link RemoteService}).
* The interface adds logging, latency testing and usage of the service in a safe way that will not
* add stress to the remote service when connectivity issues occur.
*/
@Slf4j
public class ServiceAmbassador implements RemoteServiceInterface {
private static final Logger LOGGER = LoggerFactory.getLogger(ServiceAmbassador.class);
private static final int RETRIES = 3;
private static final int DELAY_MS = 3000;
@ -52,7 +53,7 @@ public class ServiceAmbassador implements RemoteServiceInterface {
var result = RemoteService.getRemoteService().doRemoteFunction(value);
var timeTaken = System.currentTimeMillis() - startTime;
LOGGER.info("Time taken (ms): {}", timeTaken);
LOGGER.info("Time taken (ms): " + timeTaken);
return result;
}
@ -66,13 +67,12 @@ public class ServiceAmbassador implements RemoteServiceInterface {
}
if ((result = checkLatency(value)) == FAILURE.getRemoteServiceStatusValue()) {
LOGGER.info("Failed to reach remote: ({})", i + 1);
LOGGER.info("Failed to reach remote: (" + (i + 1) + ")");
retries++;
try {
sleep(DELAY_MS);
} catch (InterruptedException e) {
LOGGER.error("Thread sleep state interrupted", e);
Thread.currentThread().interrupt();
}
} else {
break;

View File

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

View File

@ -23,11 +23,13 @@
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>
<artifactId>api-gateway</artifactId>
<groupId>com.iluwatar</groupId>
<version>1.26.0-SNAPSHOT</version>
<version>1.24.0-SNAPSHOT</version>
</parent>
<modelVersion>4.0.0</modelVersion>
<artifactId>api-gateway-service</artifactId>
@ -52,6 +54,7 @@
<scope>test</scope>
</dependency>
</dependencies>
<build>
<plugins>
<plugin>

View File

@ -24,7 +24,8 @@
package com.iluwatar.api.gateway;
import javax.annotation.Resource;
import org.springframework.web.bind.annotation.GetMapping;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.RequestMethod;
import org.springframework.web.bind.annotation.RestController;
/**
@ -44,7 +45,7 @@ public class ApiGateway {
*
* @return Product information for clients on a desktop
*/
@GetMapping("/desktop")
@RequestMapping(path = "/desktop", method = RequestMethod.GET)
public DesktopProduct getProductDesktop() {
var desktopProduct = new DesktopProduct();
desktopProduct.setImagePath(imageClient.getImagePath());
@ -57,7 +58,7 @@ public class ApiGateway {
*
* @return Product information for clients on a mobile device
*/
@GetMapping("/mobile")
@RequestMapping(path = "/mobile", method = RequestMethod.GET)
public MobileProduct getProductMobile() {
var mobileProduct = new MobileProduct();
mobileProduct.setPrice(priceClient.getPrice());

View File

@ -23,16 +23,10 @@
package com.iluwatar.api.gateway;
import lombok.Getter;
import lombok.Setter;
/**
* Encapsulates all of the information that a desktop client needs to display a product.
*/
@Getter
@Setter
public class DesktopProduct {
/**
* The price of the product.
*/
@ -43,4 +37,19 @@ public class DesktopProduct {
*/
private String imagePath;
public String getPrice() {
return price;
}
public void setPrice(String price) {
this.price = price;
}
public String getImagePath() {
return imagePath;
}
public void setImagePath(String imagePath) {
this.imagePath = imagePath;
}
}

View File

@ -23,21 +23,24 @@
package com.iluwatar.api.gateway;
import static org.slf4j.LoggerFactory.getLogger;
import java.io.IOException;
import java.net.URI;
import java.net.http.HttpClient;
import java.net.http.HttpRequest;
import java.net.http.HttpResponse;
import java.net.http.HttpResponse.BodyHandlers;
import lombok.extern.slf4j.Slf4j;
import org.slf4j.Logger;
import org.springframework.stereotype.Component;
/**
* An adapter to communicate with the Image microservice.
*/
@Slf4j
@Component
public class ImageClientImpl implements ImageClient {
private static final Logger LOGGER = getLogger(ImageClientImpl.class);
/**
* Makes a simple HTTP Get request to the Image microservice.
@ -57,11 +60,8 @@ public class ImageClientImpl implements ImageClient {
var httpResponse = httpClient.send(httpGet, BodyHandlers.ofString());
logResponse(httpResponse);
return httpResponse.body();
} catch (IOException ioe) {
LOGGER.error("Failure occurred while getting image path", ioe);
} catch (InterruptedException ie) {
LOGGER.error("Failure occurred while getting image path", ie);
Thread.currentThread().interrupt();
} catch (IOException | InterruptedException e) {
LOGGER.error("Failure occurred while getting image path", e);
}
return null;

View File

@ -23,17 +23,20 @@
package com.iluwatar.api.gateway;
import lombok.Getter;
import lombok.Setter;
/**
* Encapsulates all of the information that mobile client needs to display a product.
*/
@Getter
@Setter
public class MobileProduct {
/**
* The price of the product.
*/
private String price;
public String getPrice() {
return price;
}
public void setPrice(String price) {
this.price = price;
}
}

View File

@ -23,22 +23,25 @@
package com.iluwatar.api.gateway;
import static org.slf4j.LoggerFactory.getLogger;
import java.io.IOException;
import java.net.URI;
import java.net.http.HttpClient;
import java.net.http.HttpRequest;
import java.net.http.HttpResponse;
import java.net.http.HttpResponse.BodyHandlers;
import lombok.extern.slf4j.Slf4j;
import org.slf4j.Logger;
import org.springframework.stereotype.Component;
/**
* An adapter to communicate with the Price microservice.
*/
@Slf4j
@Component
public class PriceClientImpl implements PriceClient {
private static final Logger LOGGER = getLogger(PriceClientImpl.class);
/**
* Makes a simple HTTP Get request to the Price microservice.
@ -58,11 +61,8 @@ public class PriceClientImpl implements PriceClient {
var httpResponse = httpClient.send(httpGet, BodyHandlers.ofString());
logResponse(httpResponse);
return httpResponse.body();
} catch (IOException e) {
} catch (IOException | InterruptedException e) {
LOGGER.error("Failure occurred while getting price info", e);
} catch (InterruptedException e) {
LOGGER.error("Failure occurred while getting price info", e);
Thread.currentThread().interrupt();
}
return null;

View File

@ -35,7 +35,7 @@ import org.mockito.MockitoAnnotations;
/**
* Test API Gateway Pattern
*/
class ApiGatewayTest {
public class ApiGatewayTest {
@InjectMocks
private ApiGateway apiGateway;
@ -48,14 +48,14 @@ class ApiGatewayTest {
@BeforeEach
public void setup() {
MockitoAnnotations.openMocks(this);
MockitoAnnotations.initMocks(this);
}
/**
* Tests getting the data for a desktop client
*/
@Test
void testGetProductDesktop() {
public void testGetProductDesktop() {
var imagePath = "/product-image.png";
var price = "20";
when(imageClient.getImagePath()).thenReturn(imagePath);
@ -71,7 +71,7 @@ class ApiGatewayTest {
* Tests getting the data for a mobile client
*/
@Test
void testGetProductMobile() {
public void testGetProductMobile() {
var price = "20";
when(priceClient.getPrice()).thenReturn(price);

View File

@ -23,11 +23,13 @@
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>
<artifactId>api-gateway</artifactId>
<groupId>com.iluwatar</groupId>
<version>1.26.0-SNAPSHOT</version>
<version>1.24.0-SNAPSHOT</version>
</parent>
<modelVersion>4.0.0</modelVersion>
<artifactId>image-microservice</artifactId>
@ -47,6 +49,7 @@
<scope>test</scope>
</dependency>
</dependencies>
<build>
<plugins>
<plugin>

View File

@ -23,24 +23,27 @@
package com.iluwatar.image.microservice;
import lombok.extern.slf4j.Slf4j;
import org.springframework.web.bind.annotation.GetMapping;
import static org.slf4j.LoggerFactory.getLogger;
import org.slf4j.Logger;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.RequestMethod;
import org.springframework.web.bind.annotation.RestController;
/**
* Exposes the Image microservice's endpoints.
*/
@Slf4j
@RestController
public class ImageController {
private static final Logger LOGGER = getLogger(ImageController.class);
/**
* An endpoint for a user to retrieve an image path.
*
* @return An image path
*/
@GetMapping("/image-path")
@RequestMapping(value = "/image-path", method = RequestMethod.GET)
public String getImagePath() {
LOGGER.info("Successfully found image path");
return "/product-image.png";

View File

@ -23,17 +23,16 @@
package com.iluwatar.image.microservice;
import org.junit.jupiter.api.Test;
import static org.junit.jupiter.api.Assertions.assertEquals;
import org.junit.jupiter.api.Test;
/**
* Test for Image Rest Controller
*/
class ImageControllerTest {
public class ImageControllerTest {
@Test
void testGetImagePath() {
public void testGetImagePath() {
var imageController = new ImageController();
var imagePath = imageController.getImagePath();
assertEquals("/product-image.png", imagePath);

View File

@ -23,11 +23,13 @@
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>
<artifactId>java-design-patterns</artifactId>
<groupId>com.iluwatar</groupId>
<version>1.26.0-SNAPSHOT</version>
<version>1.24.0-SNAPSHOT</version>
</parent>
<modelVersion>4.0.0</modelVersion>
<artifactId>api-gateway</artifactId>

View File

@ -23,15 +23,19 @@
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>
<artifactId>api-gateway</artifactId>
<groupId>com.iluwatar</groupId>
<version>1.26.0-SNAPSHOT</version>
<version>1.24.0-SNAPSHOT</version>
</parent>
<modelVersion>4.0.0</modelVersion>
<artifactId>price-microservice</artifactId>
<packaging>jar</packaging>
<dependencies>
<dependency>
<groupId>org.springframework</groupId>
@ -47,6 +51,7 @@
<scope>test</scope>
</dependency>
</dependencies>
<build>
<plugins>
<plugin>

View File

@ -23,24 +23,27 @@
package com.iluwatar.price.microservice;
import lombok.extern.slf4j.Slf4j;
import org.springframework.web.bind.annotation.GetMapping;
import static org.slf4j.LoggerFactory.getLogger;
import org.slf4j.Logger;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.RequestMethod;
import org.springframework.web.bind.annotation.RestController;
/**
* Exposes the Price microservice's endpoints.
*/
@Slf4j
@RestController
public class PriceController {
private static final Logger LOGGER = getLogger(PriceController.class);
/**
* An endpoint for a user to retrieve a product's price.
*
* @return A product's price
*/
@GetMapping("/price")
@RequestMapping(value = "/price", method = RequestMethod.GET)
public String getPrice() {
LOGGER.info("Successfully found price info");
return "20";

View File

@ -23,17 +23,16 @@
package com.iluwatar.price.microservice;
import org.junit.jupiter.api.Test;
import static org.junit.jupiter.api.Assertions.assertEquals;
import org.junit.jupiter.api.Test;
/**
* Test for Price Rest Controller
*/
class PriceControllerTest {
public class PriceControllerTest {
@Test
void testgetPrice() {
public void testgetPrice() {
var priceController = new PriceController();
var price = priceController.getPrice();
assertEquals("20", price);

View File

@ -4,7 +4,6 @@ title: Arrange/Act/Assert
folder: arrange-act-assert
permalink: /patterns/arrange-act-assert/
categories: Idiom
language: en
tags:
- Testing
---
@ -82,10 +81,10 @@ Then we write our unit tests according to Arrange/Act/Assert pattern. Notice the
separated steps for each unit test.
```java
class CashAAATest {
public class CashAAATest {
@Test
void testPlus() {
public void testPlus() {
//Arrange
var cash = new Cash(3);
//Act
@ -95,7 +94,7 @@ class CashAAATest {
}
@Test
void testMinus() {
public void testMinus() {
//Arrange
var cash = new Cash(8);
//Act
@ -106,7 +105,7 @@ class CashAAATest {
}
@Test
void testInsufficientMinus() {
public void testInsufficientMinus() {
//Arrange
var cash = new Cash(1);
//Act
@ -117,7 +116,7 @@ class CashAAATest {
}
@Test
void testUpdate() {
public void testUpdate() {
//Arrange
var cash = new Cash(5);
//Act

View File

@ -23,13 +23,16 @@
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>
<artifactId>java-design-patterns</artifactId>
<groupId>com.iluwatar</groupId>
<version>1.26.0-SNAPSHOT</version>
<version>1.24.0-SNAPSHOT</version>
</parent>
<modelVersion>4.0.0</modelVersion>
<artifactId>arrange-act-assert</artifactId>
<dependencies>
<dependency>
@ -38,4 +41,4 @@
<scope>test</scope>
</dependency>
</dependencies>
</project>
</project>

View File

@ -23,17 +23,18 @@
package com.iluwatar.arrangeactassert;
import lombok.AllArgsConstructor;
/**
* Arrange/Act/Assert (AAA) is a unit test pattern. In this simple example, we have a ({@link Cash})
* object for plus, minus and counting amount.
*/
@AllArgsConstructor
public class Cash {
private int amount;
Cash(int amount) {
this.amount = amount;
}
//plus
void plus(int addend) {
amount += addend;

BIN
assets/flags/AR.png Normal file

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@ -4,166 +4,26 @@ title: Async Method Invocation
folder: async-method-invocation
permalink: /patterns/async-method-invocation/
categories: Concurrency
language: en
tags:
- Reactive
---
## Intent
Asynchronous method invocation is a pattern where the calling thread
Asynchronous method invocation is pattern where the calling thread
is not blocked while waiting results of tasks. The pattern provides parallel
processing of multiple independent tasks and retrieving the results via
callbacks or waiting until everything is done.
## Explanation
Real world example
> Launching space rockets is an exciting business. The mission command gives an order to launch and
> after some undetermined time, the rocket either launches successfully or fails miserably.
In plain words
> Asynchronous method invocation starts task processing and returns immediately before the task is
> ready. The results of the task processing are returned to the caller later.
Wikipedia says
> In multithreaded computer programming, asynchronous method invocation (AMI), also known as
> asynchronous method calls or the asynchronous pattern is a design pattern in which the call site
> is not blocked while waiting for the called code to finish. Instead, the calling thread is
> notified when the reply arrives. Polling for a reply is an undesired option.
**Programmatic Example**
In this example, we are launching space rockets and deploying lunar rovers.
The application demonstrates the async method invocation pattern. The key parts of the pattern are
`AsyncResult` which is an intermediate container for an asynchronously evaluated value,
`AsyncCallback` which can be provided to be executed on task completion and `AsyncExecutor` that
manages the execution of the async tasks.
```java
public interface AsyncResult<T> {
boolean isCompleted();
T getValue() throws ExecutionException;
void await() throws InterruptedException;
}
```
```java
public interface AsyncCallback<T> {
void onComplete(T value, Optional<Exception> ex);
}
```
```java
public interface AsyncExecutor {
<T> AsyncResult<T> startProcess(Callable<T> task);
<T> AsyncResult<T> startProcess(Callable<T> task, AsyncCallback<T> callback);
<T> T endProcess(AsyncResult<T> asyncResult) throws ExecutionException, InterruptedException;
}
```
`ThreadAsyncExecutor` is an implementation of `AsyncExecutor`. Some of its key parts are highlighted
next.
```java
public class ThreadAsyncExecutor implements AsyncExecutor {
@Override
public <T> AsyncResult<T> startProcess(Callable<T> task) {
return startProcess(task, null);
}
@Override
public <T> AsyncResult<T> startProcess(Callable<T> task, AsyncCallback<T> callback) {
var result = new CompletableResult<>(callback);
new Thread(
() -> {
try {
result.setValue(task.call());
} catch (Exception ex) {
result.setException(ex);
}
},
"executor-" + idx.incrementAndGet())
.start();
return result;
}
@Override
public <T> T endProcess(AsyncResult<T> asyncResult)
throws ExecutionException, InterruptedException {
if (!asyncResult.isCompleted()) {
asyncResult.await();
}
return asyncResult.getValue();
}
}
```
Then we are ready to launch some rockets to see how everything works together.
```java
public static void main(String[] args) throws Exception {
// construct a new executor that will run async tasks
var executor = new ThreadAsyncExecutor();
// start few async tasks with varying processing times, two last with callback handlers
final var asyncResult1 = executor.startProcess(lazyval(10, 500));
final var asyncResult2 = executor.startProcess(lazyval("test", 300));
final var asyncResult3 = executor.startProcess(lazyval(50L, 700));
final var asyncResult4 = executor.startProcess(lazyval(20, 400), callback("Deploying lunar rover"));
final var asyncResult5 =
executor.startProcess(lazyval("callback", 600), callback("Deploying lunar rover"));
// emulate processing in the current thread while async tasks are running in their own threads
Thread.sleep(350); // Oh boy, we are working hard here
log("Mission command is sipping coffee");
// wait for completion of the tasks
final var result1 = executor.endProcess(asyncResult1);
final var result2 = executor.endProcess(asyncResult2);
final var result3 = executor.endProcess(asyncResult3);
asyncResult4.await();
asyncResult5.await();
// log the results of the tasks, callbacks log immediately when complete
log("Space rocket <" + result1 + "> launch complete");
log("Space rocket <" + result2 + "> launch complete");
log("Space rocket <" + result3 + "> launch complete");
}
```
Here's the program console output.
```java
21:47:08.227 [executor-2] INFO com.iluwatar.async.method.invocation.App - Space rocket <test> launched successfully
21:47:08.269 [main] INFO com.iluwatar.async.method.invocation.App - Mission command is sipping coffee
21:47:08.318 [executor-4] INFO com.iluwatar.async.method.invocation.App - Space rocket <20> launched successfully
21:47:08.335 [executor-4] INFO com.iluwatar.async.method.invocation.App - Deploying lunar rover <20>
21:47:08.414 [executor-1] INFO com.iluwatar.async.method.invocation.App - Space rocket <10> launched successfully
21:47:08.519 [executor-5] INFO com.iluwatar.async.method.invocation.App - Space rocket <callback> launched successfully
21:47:08.519 [executor-5] INFO com.iluwatar.async.method.invocation.App - Deploying lunar rover <callback>
21:47:08.616 [executor-3] INFO com.iluwatar.async.method.invocation.App - Space rocket <50> launched successfully
21:47:08.617 [main] INFO com.iluwatar.async.method.invocation.App - Space rocket <10> launch complete
21:47:08.617 [main] INFO com.iluwatar.async.method.invocation.App - Space rocket <test> launch complete
21:47:08.618 [main] INFO com.iluwatar.async.method.invocation.App - Space rocket <50> launch complete
```
# Class diagram
![alt text](./etc/async-method-invocation.png "Async Method Invocation")
## Applicability
Use the async method invocation pattern when
Use async method invocation pattern when
* You have multiple independent tasks that can run in parallel
* You need to improve the performance of a group of sequential tasks
* You have a limited amount of processing capacity or long-running tasks and the caller should not wait for the tasks to be ready
* You have limited amount of processing capacity or long running tasks and the
caller should not wait the tasks to be ready
## Real world examples

View File

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

View File

@ -24,15 +24,14 @@
package com.iluwatar.async.method.invocation;
import java.util.concurrent.Callable;
import lombok.extern.slf4j.Slf4j;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
/**
* In this example, we are launching space rockets and deploying lunar rovers.
*
* <p>The application demonstrates the async method invocation pattern. The key parts of the
* pattern are <code>AsyncResult</code> which is an intermediate container for an asynchronously
* evaluated value, <code>AsyncCallback</code> which can be provided to be executed on task
* completion and <code>AsyncExecutor</code> that manages the execution of the async tasks.
* This application demonstrates the async method invocation pattern. Key parts of the pattern are
* <code>AsyncResult</code> which is an intermediate container for an asynchronously evaluated
* value, <code>AsyncCallback</code> which can be provided to be executed on task completion and
* <code>AsyncExecutor</code> that manages the execution of the async tasks.
*
* <p>The main method shows example flow of async invocations. The main thread starts multiple
* tasks with variable durations and then continues its own work. When the main thread has done it's
@ -56,15 +55,13 @@ import lombok.extern.slf4j.Slf4j;
* @see java.util.concurrent.CompletableFuture
* @see java.util.concurrent.ExecutorService
*/
@Slf4j
public class App {
private static final String ROCKET_LAUNCH_LOG_PATTERN = "Space rocket <%s> launched successfully";
private static final Logger LOGGER = LoggerFactory.getLogger(App.class);
/**
* Program entry point.
*/
public static void main(String[] args) throws Exception {
// construct a new executor that will run async tasks
var executor = new ThreadAsyncExecutor();
@ -73,14 +70,13 @@ public class App {
final var asyncResult1 = executor.startProcess(lazyval(10, 500));
final var asyncResult2 = executor.startProcess(lazyval("test", 300));
final var asyncResult3 = executor.startProcess(lazyval(50L, 700));
final var asyncResult4 = executor.startProcess(lazyval(20, 400),
callback("Deploying lunar rover"));
final var asyncResult4 = executor.startProcess(lazyval(20, 400), callback("Callback result 4"));
final var asyncResult5 =
executor.startProcess(lazyval("callback", 600), callback("Deploying lunar rover"));
executor.startProcess(lazyval("callback", 600), callback("Callback result 5"));
// emulate processing in the current thread while async tasks are running in their own threads
Thread.sleep(350); // Oh boy, we are working hard here
log("Mission command is sipping coffee");
Thread.sleep(350); // Oh boy I'm working hard here
log("Some hard work done");
// wait for completion of the tasks
final var result1 = executor.endProcess(asyncResult1);
@ -90,9 +86,9 @@ public class App {
asyncResult5.await();
// log the results of the tasks, callbacks log immediately when complete
log(String.format(ROCKET_LAUNCH_LOG_PATTERN, result1));
log(String.format(ROCKET_LAUNCH_LOG_PATTERN, result2));
log(String.format(ROCKET_LAUNCH_LOG_PATTERN, result3));
log("Result 1: " + result1);
log("Result 2: " + result2);
log("Result 3: " + result3);
}
/**
@ -105,7 +101,7 @@ public class App {
private static <T> Callable<T> lazyval(T value, long delayMillis) {
return () -> {
Thread.sleep(delayMillis);
log(String.format(ROCKET_LAUNCH_LOG_PATTERN, value));
log("Task completed with: " + value);
return value;
};
}
@ -121,7 +117,7 @@ public class App {
if (ex.isPresent()) {
log(name + " failed: " + ex.map(Exception::getMessage).orElse(""));
} else {
log(name + " <" + value + ">");
log(name + ": " + value);
}
};
}

View File

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

View File

@ -4,137 +4,24 @@ title: Balking
folder: balking
permalink: /patterns/balking/
categories: Concurrency
language: en
tags:
- Decoupling
---
## Intent
Balking Pattern is used to prevent an object from executing a certain code if it is in an incomplete
or inappropriate state.
## Explanation
Real world example
> There's a start-button in a washing machine to initiate the laundry washing. When the washing
> machine is inactive the button works as expected, but if it's already washing the button does
> nothing.
In plain words
> Using the balking pattern, a certain code executes only if the object is in particular state.
Wikipedia says
> The balking pattern is a software design pattern that only executes an action on an object when
> the object is in a particular state. For example, if an object reads ZIP files and a calling
> method invokes a get method on the object when the ZIP file is not open, the object would "balk"
> at the request.
**Programmatic Example**
In this example implementation, `WashingMachine` is an object that has two states in which it can
be: ENABLED and WASHING. If the machine is ENABLED, the state changes to WASHING using a thread-safe
method. On the other hand, if it already has been washing and any other thread executes `wash()`
it won't do that and returns without doing anything.
Here are the relevant parts of the `WashingMachine` class.
```java
@Slf4j
public class WashingMachine {
private final DelayProvider delayProvider;
private WashingMachineState washingMachineState;
public WashingMachine(DelayProvider delayProvider) {
this.delayProvider = delayProvider;
this.washingMachineState = WashingMachineState.ENABLED;
}
public WashingMachineState getWashingMachineState() {
return washingMachineState;
}
public void wash() {
synchronized (this) {
var machineState = getWashingMachineState();
LOGGER.info("{}: Actual machine state: {}", Thread.currentThread().getName(), machineState);
if (this.washingMachineState == WashingMachineState.WASHING) {
LOGGER.error("Cannot wash if the machine has been already washing!");
return;
}
this.washingMachineState = WashingMachineState.WASHING;
}
LOGGER.info("{}: Doing the washing", Thread.currentThread().getName());
this.delayProvider.executeAfterDelay(50, TimeUnit.MILLISECONDS, this::endOfWashing);
}
public synchronized void endOfWashing() {
washingMachineState = WashingMachineState.ENABLED;
LOGGER.info("{}: Washing completed.", Thread.currentThread().getId());
}
}
```
Here's the simple `DelayProvider` interface used by the `WashingMachine`.
```java
public interface DelayProvider {
void executeAfterDelay(long interval, TimeUnit timeUnit, Runnable task);
}
```
Now we introduce the application using the `WashingMachine`.
```java
public static void main(String... args) {
final var washingMachine = new WashingMachine();
var executorService = Executors.newFixedThreadPool(3);
for (int i = 0; i < 3; i++) {
executorService.execute(washingMachine::wash);
}
executorService.shutdown();
try {
executorService.awaitTermination(10, TimeUnit.SECONDS);
} catch (InterruptedException ie) {
LOGGER.error("ERROR: Waiting on executor service shutdown!");
Thread.currentThread().interrupt();
}
}
```
Here is the console output of the program.
```
14:02:52.268 [pool-1-thread-2] INFO com.iluwatar.balking.WashingMachine - pool-1-thread-2: Actual machine state: ENABLED
14:02:52.272 [pool-1-thread-2] INFO com.iluwatar.balking.WashingMachine - pool-1-thread-2: Doing the washing
14:02:52.272 [pool-1-thread-3] INFO com.iluwatar.balking.WashingMachine - pool-1-thread-3: Actual machine state: WASHING
14:02:52.273 [pool-1-thread-3] ERROR com.iluwatar.balking.WashingMachine - Cannot wash if the machine has been already washing!
14:02:52.273 [pool-1-thread-1] INFO com.iluwatar.balking.WashingMachine - pool-1-thread-1: Actual machine state: WASHING
14:02:52.273 [pool-1-thread-1] ERROR com.iluwatar.balking.WashingMachine - Cannot wash if the machine has been already washing!
14:02:52.324 [pool-1-thread-2] INFO com.iluwatar.balking.WashingMachine - 14: Washing completed.
```
Balking Pattern is used to prevent an object from executing certain code if it is an
incomplete or inappropriate state
## Class diagram
![alt text](./etc/balking.png "Balking")
## Applicability
Use the Balking pattern when
* You want to invoke an action on an object only when it is in a particular state
* Objects are generally only in a state that is prone to balking temporarily but for an unknown
amount of time
* you want to invoke an action on an object only when it is in a particular state
* objects are generally only in a state that is prone to balking temporarily
but for an unknown amount of time
## Related patterns
* [Guarded Suspension Pattern](https://java-design-patterns.com/patterns/guarded-suspension/)
* [Double Checked Locking Pattern](https://java-design-patterns.com/patterns/double-checked-locking/)
## Credits
* [Patterns in Java: A Catalog of Reusable Design Patterns Illustrated with UML, 2nd Edition, Volume 1](https://www.amazon.com/gp/product/0471227293/ref=as_li_qf_asin_il_tl?ie=UTF8&tag=javadesignpat-20&creative=9325&linkCode=as2&creativeASIN=0471227293&linkId=0e39a59ffaab93fb476036fecb637b99)
* Guarded Suspension Pattern
* Double Checked Locking Pattern

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