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Author SHA1 Message Date
9323e4e741 Merge branch 'master' into all-contributors/add-Harshrajsinh
# Conflicts:
#	.all-contributorsrc
#	README.md
2020-07-29 19:44:33 +03:00
f1b7574932 docs: update .all-contributorsrc [skip ci] 2020-07-28 17:12:02 +00:00
0cc1b20415 docs: update README.md [skip ci] 2020-07-28 17:12:01 +00:00
904 changed files with 6178 additions and 17694 deletions

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@ -291,43 +291,6 @@
"code"
]
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"login": "Harshrajsinh",
"name": "Harshraj Thakor",
@ -748,8 +711,7 @@
"avatar_url": "https://avatars1.githubusercontent.com/u/7418012?v=4",
"profile": "https://github.com/hbothra15",
"contributions": [
"code",
"design"
"code"
]
},
{
@ -904,479 +866,6 @@
"contributions": [
"code"
]
},
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},
{
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"profile": "https://www.stefan-birkner.de",
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]
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"profile": "https://github.com/fedorskvorcov",
"contributions": [
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]
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]
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]
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]
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@ -1,80 +0,0 @@
#
# The MIT License
# Copyright © 2014-2019 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.
#
# 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
name: Java CI
on:
push:
branches: [ master ]
jobs:
build:
runs-on: ubuntu-20.04
steps:
- name: Checkout Code
uses: actions/checkout@v2
with:
# Disabling shallow clone for improving relevancy of SonarQube reporting
fetch-depth: 0
- name: Set up JDK 11
uses: actions/setup-java@v1
with:
java-version: 11
- name: Cache SonarCloud packages
uses: actions/cache@v2
with:
path: ~/.sonar/cache
key: ${{ runner.os }}-sonar
restore-keys: ${{ runner.os }}-sonar
- name: Cache Maven dependencies
uses: actions/cache@v2
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
# The SonarQube analysis is only for the master branch of the main repository.
# SonarQube scan does not work for forked repositories try changing it to xvfb-run mvn clean verify
# See https://jira.sonarsource.com/browse/MMF-1371
- name: Build with Maven and run SonarQube analysis
run: xvfb-run mvn clean verify org.sonarsource.scanner.maven:sonar-maven-plugin:sonar
env:
# These two env variables are needed for sonar analysis
GITHUB_TOKEN: ${{ secrets.GITHUB_TOKEN }}
SONAR_TOKEN: ${{ secrets.SONAR_TOKEN }}

View File

@ -24,41 +24,37 @@
# 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
name: Java PR Builder
name: Java CI with Maven
on:
push:
branches: [ master ]
pull_request:
branches: [ master ]
types: [ opened, reopened, synchronize, labeled, unlabeled ]
jobs:
build:
runs-on: ubuntu-20.04
runs-on: ubuntu-18.04
steps:
- name: Checkout Code
uses: actions/checkout@v2
- uses: actions/checkout@v2
- name: Set up JDK 11
uses: actions/setup-java@v1
with:
java-version: 11
- name: Cache Maven Dependecies
uses: actions/cache@v2
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
# This worflow is only for building Pull Requests, the master branch runs Sonar analysis on the main repository.
# SonarQube scan does not work for forked repositories.
run: sudo apt-get install xvfb
# SonarQube scan does not work for forked repositories
# See https://jira.sonarsource.com/browse/MMF-1371
- name: Build with Maven
if: github.ref != 'refs/heads/master'
run: xvfb-run mvn clean verify
- name: Build with Maven and run SonarQube analysis
if: github.ref == 'refs/heads/master'
run: xvfb-run mvn clean verify org.sonarsource.scanner.maven:sonar-maven-plugin:sonar
env:
# These two env variables are needed for sonar analysis
GITHUB_TOKEN: ${{ secrets.REPOSITORY_ACCESS_TOKEN }}
SONAR_TOKEN: ${{ secrets.SONAR_TOKEN }}

290
README.md
View File

@ -6,19 +6,12 @@
![Java CI with Maven](https://github.com/iluwatar/java-design-patterns/workflows/Java%20CI%20with%20Maven/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)
[![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)
[![Sonarcloud Status](https://sonarcloud.io/api/project_badges/measure?project=iluwatar_java-design-patterns&metric=alert_status)](https://sonarcloud.io/dashboard?id=iluwatar_java-design-patterns)
<!-- ALL-CONTRIBUTORS-BADGE:START - Do not remove or modify this section -->
[![All Contributors](https://img.shields.io/badge/all_contributors-151-orange.svg?style=flat-square)](#contributors-)
[![All Contributors](https://img.shields.io/badge/all_contributors-32-orange.svg?style=flat-square)](#contributors-)
<!-- ALL-CONTRIBUTORS-BADGE:END -->
<br/>
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),
<br/>
# Introduction
Design patterns are the best formalized practices a programmer can use to
@ -37,7 +30,7 @@ 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 as
programming tutorials on how to implement a specific pattern. We use the most
programming tutorials how to implement a specific pattern. We use the most
popular battle-proven open source Java technologies.
Before you dive into the material, you should be familiar with various
@ -76,235 +69,150 @@ This project is licensed under the terms of the MIT license.
<!-- markdownlint-disable -->
<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="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="https://github.com/iluwatar"><img src="https://avatars1.githubusercontent.com/u/582346?v=4" width="100px;" alt=""/><br /><sub><b>Ilkka Seppälä</b></sub></a><br /><a href="#projectManagement-iluwatar" title="Project Management">📆</a> <a href="#maintenance-iluwatar" title="Maintenance">🚧</a> <a href="#content-iluwatar" title="Content">🖋</a></td>
<td align="center"><a href="https://github.com/amit1307"><img src="https://avatars0.githubusercontent.com/u/23420222?v=4" 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" 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" 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>
</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>
<td align="center"><a href="http://www.joemccarthy.co.uk"><img src="https://avatars0.githubusercontent.com/u/4526195?v=4" 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" 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" 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" 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://twitter.com/i_sabiq"><img src="https://avatars1.githubusercontent.com/u/19510920?v=4" 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" 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" 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" 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>
</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>
<td align="center"><a href="https://github.com/Crossy147"><img src="https://avatars2.githubusercontent.com/u/7272996?v=4" 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" 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" 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" 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>
<td align="center"><a href="http://colinbut.com"><img src="https://avatars2.githubusercontent.com/u/10725674?v=4?s=100" width="100px;" alt=""/><br /><sub><b>Colin But</b></sub></a><br /><a href="https://github.com/iluwatar/java-design-patterns/commits?author=colinbut" title="Code">💻</a></td>
<td align="center"><a href="https://github.com/TylerMcConville"><img src="https://avatars0.githubusercontent.com/u/4946449?v=4" 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" 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" width="100px;" alt=""/><br /><sub><b>nikhilbarar</b></sub></a><br /><a href="https://github.com/iluwatar/java-design-patterns/commits?author=nikhilbarar" title="Code">💻</a></td>
<td align="center"><a href="http://colinbut.com"><img src="https://avatars2.githubusercontent.com/u/10725674?v=4" width="100px;" alt=""/><br /><sub><b>Colin But</b></sub></a><br /><a href="https://github.com/iluwatar/java-design-patterns/commits?author=colinbut" title="Code">💻</a></td>
</tr>
<tr>
<td align="center"><a href="https://github.com/ruslanpa"><img src="https://avatars2.githubusercontent.com/u/1503411?v=4?s=100" width="100px;" alt=""/><br /><sub><b>Ruslan</b></sub></a><br /><a href="https://github.com/iluwatar/java-design-patterns/commits?author=ruslanpa" title="Code">💻</a></td>
<td align="center"><a href="https://github.com/JuhoKang"><img src="https://avatars1.githubusercontent.com/u/4745294?v=4?s=100" width="100px;" alt=""/><br /><sub><b>Juho Kang</b></sub></a><br /><a href="https://github.com/iluwatar/java-design-patterns/commits?author=JuhoKang" title="Code">💻</a></td>
<td align="center"><a href="https://github.com/dheeraj-mummareddy"><img src="https://avatars2.githubusercontent.com/u/7002230?v=4?s=100" width="100px;" alt=""/><br /><sub><b>Dheeraj Mummareddy</b></sub></a><br /><a href="https://github.com/iluwatar/java-design-patterns/commits?author=dheeraj-mummareddy" title="Code">💻</a></td>
<td align="center"><a href="https://www.bernardosulzbach.com"><img src="https://avatars0.githubusercontent.com/u/8271090?v=4?s=100" width="100px;" alt=""/><br /><sub><b>Bernardo Sulzbach</b></sub></a><br /><a href="https://github.com/iluwatar/java-design-patterns/commits?author=bernardosulzbach" title="Code">💻</a></td>
<td align="center"><a href="https://github.com/ruslanpa"><img src="https://avatars2.githubusercontent.com/u/1503411?v=4" width="100px;" alt=""/><br /><sub><b>Ruslan</b></sub></a><br /><a href="https://github.com/iluwatar/java-design-patterns/commits?author=ruslanpa" title="Code">💻</a></td>
<td align="center"><a href="https://github.com/JuhoKang"><img src="https://avatars1.githubusercontent.com/u/4745294?v=4" 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" 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" 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>
<td align="center"><a href="https://github.com/4lexis"><img src="https://avatars0.githubusercontent.com/u/19871727?v=4" 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" 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" 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" 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/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://github.com/gvsharma"><img src="https://avatars1.githubusercontent.com/u/6648152?v=4" 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" 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" 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://github.com/npczwh"><img src="https://avatars0.githubusercontent.com/u/14066422?v=4" 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>
</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>
<td align="center"><a href="https://github.com/qza"><img src="https://avatars3.githubusercontent.com/u/233149?v=4" 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" 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" 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" 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>
</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="https://twitter.com/StPitsios"><img src="https://avatars1.githubusercontent.com/u/6773603?v=4" 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/robertt240"><img src="https://avatars1.githubusercontent.com/u/9137432?v=4" 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://t.me/paul_docker"><img src="https://avatars1.githubusercontent.com/u/2404785?v=4" 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://github.com/gwildor28"><img src="https://avatars0.githubusercontent.com/u/16000365?v=4" width="100px;" alt=""/><br /><sub><b>gwildor28</b></sub></a><br /><a href="https://github.com/iluwatar/java-design-patterns/commits?author=gwildor28" 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>
<td align="center"><a href="https://github.com/amit2103"><img src="https://avatars3.githubusercontent.com/u/7566692?v=4" 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/hoswey"><img src="https://avatars3.githubusercontent.com/u/3689445?v=4" 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://www.linkedin.com/in/gopinathlangote/"><img src="https://avatars2.githubusercontent.com/u/10210778?v=4" 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/ThatGuyWithTheHat"><img src="https://avatars0.githubusercontent.com/u/24470582?v=4" width="100px;" alt=""/><br /><sub><b>Matt</b></sub></a><br /><a href="#content-ThatGuyWithTheHat" title="Content">🖋</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>
<td align="center"><a href="https://github.com/sankypanhale"><img src="https://avatars1.githubusercontent.com/u/6478783?v=4?s=100" width="100px;" alt=""/><br /><sub><b>Sanket Panhale</b></sub></a><br /><a href="#content-sankypanhale" title="Content">🖋</a></td>
<td align="center"><a href="https://github.com/vehpsr"><img src="https://avatars2.githubusercontent.com/u/3133265?v=4" 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/Azureyjt"><img src="https://avatars2.githubusercontent.com/u/18476317?v=4" 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/mookkiah"><img src="https://avatars1.githubusercontent.com/u/8975264?v=4" 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://llorllale.github.io/"><img src="https://avatars1.githubusercontent.com/u/2019896?v=4" 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://github.com/staillebois"><img src="https://avatars0.githubusercontent.com/u/23701200?v=4?s=100" width="100px;" alt=""/><br /><sub><b>staillebois</b></sub></a><br /><a href="https://github.com/iluwatar/java-design-patterns/commits?author=staillebois" title="Code">💻</a></td>
<td align="center"><a href="https://github.com/valdar-hu"><img src="https://avatars3.githubusercontent.com/u/17962817?v=4?s=100" width="100px;" alt=""/><br /><sub><b>Krisztián Nagy</b></sub></a><br /><a href="https://github.com/iluwatar/java-design-patterns/commits?author=valdar-hu" title="Code">💻</a></td>
<td align="center"><a href="https://www.vanogrid.com"><img src="https://avatars0.githubusercontent.com/u/4307918?v=4?s=100" width="100px;" alt=""/><br /><sub><b>Alexander Ivanov</b></sub></a><br /><a href="https://github.com/iluwatar/java-design-patterns/commits?author=vanogrid" title="Code">💻</a></td>
<td align="center"><a href="https://github.com/yosfik"><img src="https://avatars3.githubusercontent.com/u/4850270?v=4?s=100" width="100px;" alt=""/><br /><sub><b>Yosfik Alqadri</b></sub></a><br /><a href="https://github.com/iluwatar/java-design-patterns/commits?author=yosfik" title="Code">💻</a></td>
<td align="center"><a href="https://www.kevinpeters.net/about/"><img src="https://avatars1.githubusercontent.com/u/12736734?v=4" 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://github.com/hbothra15"><img src="https://avatars1.githubusercontent.com/u/7418012?v=4" 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></td>
<td align="center"><a href="https://github.com/giorgosmav21"><img src="https://avatars2.githubusercontent.com/u/22855493?v=4" 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/oconnelc"><img src="https://avatars0.githubusercontent.com/u/1112973?v=4" 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/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>
<td align="center"><a href="https://github.com/leogtzr"><img src="https://avatars0.githubusercontent.com/u/1211969?v=4" 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://bitbucket.org/hannespernpeintner/"><img src="https://avatars3.githubusercontent.com/u/1679437?v=4" width="100px;" alt=""/><br /><sub><b>Hannes</b></sub></a><br /><a href="https://github.com/iluwatar/java-design-patterns/commits?author=hannespernpeintner" title="Code">💻</a></td>
<td align="center"><a href="https://github.com/dgruntz"><img src="https://avatars0.githubusercontent.com/u/1516800?v=4" width="100px;" alt=""/><br /><sub><b>Dominik Gruntz</b></sub></a><br /><a href="https://github.com/iluwatar/java-design-patterns/commits?author=dgruntz" title="Code">💻</a></td>
<td align="center"><a href="https://christofferh.com"><img src="https://avatars1.githubusercontent.com/u/767643?v=4" 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>
</tr>
<tr>
<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/AnaghaSasikumar"><img src="https://avatars2.githubusercontent.com/u/42939261?v=4" width="100px;" alt=""/><br /><sub><b>AnaghaSasikumar</b></sub></a><br /><a href="https://github.com/iluwatar/java-design-patterns/commits?author=AnaghaSasikumar" title="Code">💻</a></td>
<td align="center"><a href="https://github.com/waisuan"><img src="https://avatars2.githubusercontent.com/u/10975700?v=4" 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="http://www.wramdemark.se"><img src="https://avatars2.githubusercontent.com/u/7052193?v=4" width="100px;" alt=""/><br /><sub><b>Per Wramdemark</b></sub></a><br /><a href="https://github.com/iluwatar/java-design-patterns/commits?author=perwramdemark" title="Code">💻</a></td>
<td align="center"><a href="http://leonmak.me"><img src="https://avatars3.githubusercontent.com/u/13071508?v=4" 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>
</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>
<td align="center"><a href="https://github.com/kanwarpreet25"><img src="https://avatars0.githubusercontent.com/u/39183641?v=4" width="100px;" alt=""/><br /><sub><b>kanwarpreet25</b></sub></a><br /><a href="https://github.com/iluwatar/java-design-patterns/commits?author=kanwarpreet25" title="Code">💻</a></td>
<td align="center"><a href="https://github.com/MSaifAsif"><img src="https://avatars1.githubusercontent.com/u/6280554?v=4" 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://alwayswithme.github.io"><img src="https://avatars3.githubusercontent.com/u/3234786?v=4" 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://ranjeet-floyd.github.io"><img src="https://avatars0.githubusercontent.com/u/1992972?v=4" 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>
</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="http://mitchell-irvin.com"><img src="https://avatars0.githubusercontent.com/u/16233245?v=4" 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://github.com/jarpit96"><img src="https://avatars2.githubusercontent.com/u/10098713?v=4" width="100px;" alt=""/><br /><sub><b>Arpit Jain</b></sub></a><br /><a href="https://github.com/iluwatar/java-design-patterns/commits?author=jarpit96" title="Code">💻</a></td>
<td align="center"><a href="https://github.com/hoangnam2261"><img src="https://avatars2.githubusercontent.com/u/31692990?v=4" 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/fanofxiaofeng"><img src="https://avatars0.githubusercontent.com/u/3983683?v=4" 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>
</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>
<td align="center"><a href="https://github.com/kirill-vlasov"><img src="https://avatars3.githubusercontent.com/u/16112495?v=4" 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://joningi.net"><img src="https://avatars2.githubusercontent.com/u/6115148?v=4" width="100px;" alt=""/><br /><sub><b>Jón Ingi Sveinbjörnsson</b></sub></a><br /><a href="https://github.com/iluwatar/java-design-patterns/commits?author=joningiwork" title="Code">💻</a></td>
<td align="center"><a href="https://github.com/dmitraver"><img src="https://avatars3.githubusercontent.com/u/1798156?v=4" 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/besok"><img src="https://avatars2.githubusercontent.com/u/29834592?v=4" 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>
</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>
<td align="center"><a href="https://github.com/dgruntz"><img src="https://avatars0.githubusercontent.com/u/1516800?v=4?s=100" width="100px;" alt=""/><br /><sub><b>Dominik Gruntz</b></sub></a><br /><a href="https://github.com/iluwatar/java-design-patterns/commits?author=dgruntz" title="Code">💻</a></td>
<td align="center"><a href="https://github.com/baislsl"><img src="https://avatars0.githubusercontent.com/u/17060584?v=4" 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="http://adamski.pro"><img src="https://avatars1.githubusercontent.com/u/6537430?v=4" 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/Rzeposlaw"><img src="https://avatars2.githubusercontent.com/u/18425745?v=4" 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://www.devsedge.net/"><img src="https://avatars0.githubusercontent.com/u/9956006?v=4" 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>
</tr>
<tr>
<td align="center"><a href="https://bitbucket.org/hannespernpeintner/"><img src="https://avatars3.githubusercontent.com/u/1679437?v=4?s=100" width="100px;" alt=""/><br /><sub><b>Hannes</b></sub></a><br /><a href="https://github.com/iluwatar/java-design-patterns/commits?author=hannespernpeintner" title="Code">💻</a></td>
<td align="center"><a href="https://github.com/leogtzr"><img src="https://avatars0.githubusercontent.com/u/1211969?v=4?s=100" width="100px;" alt=""/><br /><sub><b>Leo Gutiérrez Ramírez</b></sub></a><br /><a href="https://github.com/iluwatar/java-design-patterns/commits?author=leogtzr" title="Code">💻</a></td>
<td align="center"><a href="https://github.com/npczwh"><img src="https://avatars0.githubusercontent.com/u/14066422?v=4?s=100" width="100px;" alt=""/><br /><sub><b>Zhang WH</b></sub></a><br /><a href="https://github.com/iluwatar/java-design-patterns/commits?author=npczwh" title="Code">💻</a></td>
<td align="center"><a href="https://github.com/oconnelc"><img src="https://avatars0.githubusercontent.com/u/1112973?v=4?s=100" width="100px;" alt=""/><br /><sub><b>Christopher O'Connell</b></sub></a><br /><a href="https://github.com/iluwatar/java-design-patterns/commits?author=oconnelc" title="Code">💻</a></td>
<td align="center"><a href="https://github.com/Juaanma"><img src="https://avatars3.githubusercontent.com/u/7390500?v=4" width="100px;" alt=""/><br /><sub><b>Juan Manuel Suárez</b></sub></a><br /><a href="https://github.com/iluwatar/java-design-patterns/commits?author=Juaanma" title="Code">💻</a></td>
<td align="center"><a href="https://github.com/7agustibm"><img src="https://avatars0.githubusercontent.com/u/8149332?v=4" 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/yosfik"><img src="https://avatars3.githubusercontent.com/u/4850270?v=4" width="100px;" alt=""/><br /><sub><b>Yosfik Alqadri</b></sub></a><br /><a href="https://github.com/iluwatar/java-design-patterns/commits?author=yosfik" title="Code">💻</a></td>
<td align="center"><a href="https://www.vanogrid.com"><img src="https://avatars0.githubusercontent.com/u/4307918?v=4" 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>
</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>
<td align="center"><a href="https://github.com/valdar-hu"><img src="https://avatars3.githubusercontent.com/u/17962817?v=4" width="100px;" alt=""/><br /><sub><b>Krisztián Nagy</b></sub></a><br /><a href="https://github.com/iluwatar/java-design-patterns/commits?author=valdar-hu" title="Code">💻</a></td>
<td align="center"><a href="https://github.com/staillebois"><img src="https://avatars0.githubusercontent.com/u/23701200?v=4" width="100px;" alt=""/><br /><sub><b>staillebois</b></sub></a><br /><a href="https://github.com/iluwatar/java-design-patterns/commits?author=staillebois" title="Code">💻</a></td>
<td align="center"><a href="https://github.com/sankypanhale"><img src="https://avatars1.githubusercontent.com/u/6478783?v=4" width="100px;" alt=""/><br /><sub><b>Sanket Panhale</b></sub></a><br /><a href="#content-sankypanhale" title="Content">🖋</a></td>
<td align="center"><a href="https://github.com/prafful1"><img src="https://avatars0.githubusercontent.com/u/14350274?v=4" width="100px;" alt=""/><br /><sub><b>Prafful Agarwal</b></sub></a><br /><a href="#content-prafful1" title="Content">🖋</a></td>
</tr>
<tr>
<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://przemeknowak.com"><img src="https://avatars1.githubusercontent.com/u/3254609?v=4" 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/lbroman"><img src="https://avatars1.githubusercontent.com/u/86007?v=4" 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="http://about.me/kaiwinter"><img src="https://avatars0.githubusercontent.com/u/110982?v=4" width="100px;" alt=""/><br /><sub><b>Kai Winter</b></sub></a><br /><a href="https://github.com/iluwatar/java-design-patterns/commits?author=kaiwinter" title="Code">💻</a></td>
<td align="center"><a href="https://github.com/jjjimenez100"><img src="https://avatars3.githubusercontent.com/u/22243493?v=4" 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>
</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>
<td align="center"><a href="https://about.me/dzmitryh"><img src="https://avatars2.githubusercontent.com/u/5390492?v=4" 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="http://ccygnus.com/"><img src="https://avatars1.githubusercontent.com/u/9342724?v=4" 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://github.com/anthonycampbell"><img src="https://avatars3.githubusercontent.com/u/10249255?v=4" width="100px;" alt=""/><br /><sub><b>anthony</b></sub></a><br /><a href="https://github.com/iluwatar/java-design-patterns/commits?author=anthonycampbell" title="Code">💻</a></td>
<td align="center"><a href="https://github.com/amogozov"><img src="https://avatars3.githubusercontent.com/u/7372215?v=4" 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>
</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>
</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>
<td align="center"><a href="https://github.com/grzesiekkedzior"><img src="https://avatars3.githubusercontent.com/u/23739158?v=4?s=100" width="100px;" alt=""/><br /><sub><b>grzesiekkedzior</b></sub></a><br /><a href="https://github.com/iluwatar/java-design-patterns/commits?author=grzesiekkedzior" title="Code">💻</a> <a href="https://github.com/iluwatar/java-design-patterns/pulls?q=is%3Apr+reviewed-by%3Agrzesiekkedzior" title="Reviewed Pull Requests">👀</a></td>
</tr>
<tr>
<td align="center"><a href="https://github.com/sivasubramanim"><img src="https://avatars2.githubusercontent.com/u/51107434?v=4?s=100" width="100px;" alt=""/><br /><sub><b>Sivasubramani M</b></sub></a><br /><a href="https://github.com/iluwatar/java-design-patterns/commits?author=sivasubramanim" title="Code">💻</a></td>
<td align="center"><a href="https://github.com/d4gg4d"><img src="https://avatars2.githubusercontent.com/u/99457?v=4?s=100" width="100px;" alt=""/><br /><sub><b>Sami Airaksinen</b></sub></a><br /><a href="https://github.com/iluwatar/java-design-patterns/commits?author=d4gg4d" title="Code">💻</a></td>
<td align="center"><a href="https://github.com/vertti"><img src="https://avatars0.githubusercontent.com/u/557751?v=4?s=100" width="100px;" alt=""/><br /><sub><b>Janne Sinivirta</b></sub></a><br /><a href="https://github.com/iluwatar/java-design-patterns/commits?author=vertti" title="Code">💻</a></td>
<td align="center"><a href="https://github.com/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://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>
</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="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>
</tr>
<tr>
<td align="center"><a href="https://github.com/swarajsaaj"><img src="https://avatars2.githubusercontent.com/u/6285049?v=4?s=100" width="100px;" alt=""/><br /><sub><b>Swaraj</b></sub></a><br /><a href="https://github.com/iluwatar/java-design-patterns/commits?author=swarajsaaj" title="Code">💻</a></td>
<td align="center"><a href="http://christophflick.de"><img src="https://avatars0.githubusercontent.com/u/4465376?v=4?s=100" width="100px;" alt=""/><br /><sub><b>Christoph Flick</b></sub></a><br /><a href="https://github.com/iluwatar/java-design-patterns/commits?author=ChFlick" title="Documentation">📖</a></td>
<td align="center"><a href="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>
<tr>
<td align="center"><a href="https://github.com/akashchandwani"><img src="https://avatars2.githubusercontent.com/u/3483277?v=4?s=100" width="100px;" alt=""/><br /><sub><b>Akash Chandwani</b></sub></a><br /><a href="https://github.com/iluwatar/java-design-patterns/pulls?q=is%3Apr+reviewed-by%3Aakashchandwani" title="Reviewed Pull Requests">👀</a></td>
<td align="center"><a href="http://www.linkedin.com/in/manannikov"><img src="https://avatars2.githubusercontent.com/u/7019769?v=4?s=100" width="100px;" alt=""/><br /><sub><b>Pavlo Manannikov</b></sub></a><br /><a href="https://github.com/iluwatar/java-design-patterns/commits?author=manannikov" title="Code">💻</a></td>
<td align="center"><a href="https://github.com/eimanip"><img src="https://avatars0.githubusercontent.com/u/20307301?v=4?s=100" width="100px;" alt=""/><br /><sub><b>Eiman</b></sub></a><br /><a href="https://github.com/iluwatar/java-design-patterns/commits?author=eimanip" title="Code">💻</a></td>
<td align="center"><a href="https://github.com/OrangePants-R"><img src="https://avatars0.githubusercontent.com/u/42976136?v=4?s=100" width="100px;" alt=""/><br /><sub><b>Rocky</b></sub></a><br /><a href="https://github.com/iluwatar/java-design-patterns/commits?author=OrangePants-R" title="Documentation">📖</a></td>
</tr>
<tr>
<td align="center"><a href="https://ibrahimalii.github.io/"><img src="https://avatars2.githubusercontent.com/u/21141301?v=4?s=100" width="100px;" alt=""/><br /><sub><b>Ibrahim ali abdelghany</b></sub></a><br /><a href="https://github.com/iluwatar/java-design-patterns/pulls?q=is%3Apr+reviewed-by%3AibrahimAlii" title="Reviewed Pull Requests">👀</a></td>
<td align="center"><a href="https://github.com/gkulkarni2020"><img src="https://avatars3.githubusercontent.com/u/5161548?v=4?s=100" width="100px;" alt=""/><br /><sub><b>Girish Kulkarni</b></sub></a><br /><a href="https://github.com/iluwatar/java-design-patterns/commits?author=gkulkarni2020" title="Documentation">📖</a></td>
<td align="center"><a href="https://github.com/omk13"><img src="https://avatars0.githubusercontent.com/u/59054172?v=4?s=100" width="100px;" alt=""/><br /><sub><b>Omar Karazoun</b></sub></a><br /><a href="https://github.com/iluwatar/java-design-patterns/commits?author=omk13" title="Code">💻</a></td>
<td align="center"><a href="https://github.com/jeff303"><img src="https://avatars0.githubusercontent.com/u/3521562?v=4?s=100" width="100px;" alt=""/><br /><sub><b>Jeff Evans</b></sub></a><br /><a href="https://github.com/iluwatar/java-design-patterns/commits?author=jeff303" title="Code">💻</a></td>
</tr>
<tr>
<td align="center"><a href="https://viveksb007.github.io"><img src="https://avatars1.githubusercontent.com/u/12713808?v=4?s=100" width="100px;" alt=""/><br /><sub><b>Vivek Singh</b></sub></a><br /><a href="https://github.com/iluwatar/java-design-patterns/commits?author=viveksb007" title="Code">💻</a></td>
<td align="center"><a href="https://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>
</tr>
<tr>
<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://alexsomai.com"><img src="https://avatars1.githubusercontent.com/u/5720977?v=4" 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/MaVdbussche"><img src="https://avatars1.githubusercontent.com/u/26136934?v=4" width="100px;" alt=""/><br /><sub><b>Martin Vandenbussche</b></sub></a><br /><a href="https://github.com/iluwatar/java-design-patterns/commits?author=MaVdbussche" title="Code">💻</a></td>
<td align="center"><a href="https://github.com/Harshrajsinh"><img src="https://avatars2.githubusercontent.com/u/22811531?v=4" 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>
</table>
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@ -9,182 +9,21 @@ tags:
---
## Intent
Use dynamic properties and achieve flexibility of untyped languages while keeping type-safety.
## Explanation
The Abstract Document pattern enables handling additional, non-static properties. This pattern
uses concept of traits to enable type safety and separate properties of different classes into
set of interfaces.
Real world example
> Consider a car that consists of multiple parts. However we don't know if the specific car really has all the parts, or just some of them. Our cars are dynamic and extremely flexible.
In plain words
> Abstract Document pattern allows attaching properties to objects without them knowing about it.
Wikipedia says
> An object-oriented structural design pattern for organizing objects in loosely typed key-value stores and exposing
the data using typed views. The purpose of the pattern is to achieve a high degree of flexibility between components
in a strongly typed language where new properties can be added to the object-tree on the fly, without losing the
support of type-safety. The pattern makes use of traits to separate different properties of a class into different
interfaces.
**Programmatic Example**
Let's first define the base classes `Document` and `AbstractDocument`. They basically make the object hold a property
map and any amount of child objects.
```java
public interface Document {
Void put(String key, Object value);
Object get(String key);
<T> Stream<T> children(String key, Function<Map<String, Object>, T> constructor);
}
public abstract class AbstractDocument implements Document {
private final Map<String, Object> properties;
protected AbstractDocument(Map<String, Object> properties) {
Objects.requireNonNull(properties, "properties map is required");
this.properties = properties;
}
@Override
public Void put(String key, Object value) {
properties.put(key, value);
return null;
}
@Override
public Object get(String key) {
return properties.get(key);
}
@Override
public <T> Stream<T> children(String key, Function<Map<String, Object>, T> constructor) {
return Stream.ofNullable(get(key))
.filter(Objects::nonNull)
.map(el -> (List<Map<String, Object>>) el)
.findAny()
.stream()
.flatMap(Collection::stream)
.map(constructor);
}
...
}
```
Next we define an enum `Property` and a set of interfaces for type, price, model and parts. This allows us to create
static looking interface to our `Car` class.
```java
public enum Property {
PARTS, TYPE, PRICE, MODEL
}
public interface HasType extends Document {
default Optional<String> getType() {
return Optional.ofNullable((String) get(Property.TYPE.toString()));
}
}
public interface HasPrice extends Document {
default Optional<Number> getPrice() {
return Optional.ofNullable((Number) get(Property.PRICE.toString()));
}
}
public interface HasModel extends Document {
default Optional<String> getModel() {
return Optional.ofNullable((String) get(Property.MODEL.toString()));
}
}
public interface HasParts extends Document {
default Stream<Part> getParts() {
return children(Property.PARTS.toString(), Part::new);
}
}
```
Now we are ready to introduce the `Car`.
```java
public class Car extends AbstractDocument implements HasModel, HasPrice, HasParts {
public Car(Map<String, Object> properties) {
super(properties);
}
}
```
And finally here's how we construct and use the `Car` in a full example.
```java
LOGGER.info("Constructing parts and car");
var wheelProperties = Map.of(
Property.TYPE.toString(), "wheel",
Property.MODEL.toString(), "15C",
Property.PRICE.toString(), 100L);
var doorProperties = Map.of(
Property.TYPE.toString(), "door",
Property.MODEL.toString(), "Lambo",
Property.PRICE.toString(), 300L);
var carProperties = Map.of(
Property.MODEL.toString(), "300SL",
Property.PRICE.toString(), 10000L,
Property.PARTS.toString(), List.of(wheelProperties, doorProperties));
var car = new Car(carProperties);
LOGGER.info("Here is our car:");
LOGGER.info("-> model: {}", car.getModel().orElseThrow());
LOGGER.info("-> price: {}", car.getPrice().orElseThrow());
LOGGER.info("-> parts: ");
car.getParts().forEach(p -> LOGGER.info("\t{}/{}/{}",
p.getType().orElse(null),
p.getModel().orElse(null),
p.getPrice().orElse(null))
);
// Constructing parts and car
// Here is our car:
// model: 300SL
// price: 10000
// parts:
// wheel/15C/100
// door/Lambo/300
```
Achieve flexibility of untyped languages and keep the type-safety
## Class diagram
![alt text](./etc/abstract-document.png "Abstract Document Traits and Domain")
## Applicability
## Applicability
Use the Abstract Document Pattern when
* There is a need to add new properties on the fly
* You want a flexible way to organize domain in tree like structure
* You want more loosely coupled system
* there is a need to add new properties on the fly
* you want a flexible way to organize domain in tree like structure
* you want more loosely coupled system
## Credits
* [Wikipedia: Abstract Document Pattern](https://en.wikipedia.org/wiki/Abstract_Document_Pattern)
* [Martin Fowler: Dealing with properties](http://martinfowler.com/apsupp/properties.pdf)
* [Pattern-Oriented Software Architecture Volume 4: A Pattern Language for Distributed Computing (v. 4)](https://www.amazon.com/gp/product/0470059028/ref=as_li_qf_asin_il_tl?ie=UTF8&tag=javadesignpat-20&creative=9325&linkCode=as2&creativeASIN=0470059028&linkId=e3aacaea7017258acf184f9f3283b492)

View File

@ -21,7 +21,7 @@
<parent>
<artifactId>java-design-patterns</artifactId>
<groupId>com.iluwatar</groupId>
<version>1.24.0-SNAPSHOT</version>
<version>1.23.0-SNAPSHOT</version>
</parent>
<artifactId>abstract-document</artifactId>
<dependencies>

View File

@ -43,11 +43,9 @@ public class App {
private static final Logger LOGGER = LoggerFactory.getLogger(App.class);
/**
* Program entry point.
*
* @param args command line args
* Executes the App.
*/
public static void main(String[] args) {
public App() {
LOGGER.info("Constructing parts and car");
var wheelProperties = Map.of(
@ -77,4 +75,14 @@ public class App {
p.getPrice().orElse(null))
);
}
/**
* Program entry point.
*
* @param args command line args
*/
public static void main(String[] args) {
new App();
}
}

View File

@ -32,6 +32,7 @@ import java.util.stream.Stream;
*/
public interface HasParts extends Document {
default Stream<Part> getParts() {
return children(Property.PARTS.toString(), Part::new);
}

View File

@ -32,6 +32,7 @@ import java.util.Optional;
*/
public interface HasPrice extends Document {
default Optional<Number> getPrice() {
return Optional.ofNullable((Number) get(Property.PRICE.toString()));
}

View File

@ -32,6 +32,7 @@ import java.util.Optional;
*/
public interface HasType extends Document {
default Optional<String> getType() {
return Optional.ofNullable((String) get(Property.TYPE.toString()));
}

View File

@ -21,6 +21,6 @@
* THE SOFTWARE.
*/
package com.iluwatar.filterer.threat;
public enum ThreatType { TROJAN, WORM, ROOTKIT }
module com.iluwatar.abstractdocument {
requires org.slf4j;
}

View File

@ -40,14 +40,14 @@ public class AbstractDocumentTest {
private static final String KEY = "key";
private static final String VALUE = "value";
private static class DocumentImplementation extends AbstractDocument {
private class DocumentImplementation extends AbstractDocument {
DocumentImplementation(Map<String, Object> properties) {
super(properties);
}
}
private final DocumentImplementation document = new DocumentImplementation(new HashMap<>());
private DocumentImplementation document = new DocumentImplementation(new HashMap<>());
@Test
public void shouldPutAndGetValue() {

View File

@ -25,23 +25,14 @@ package com.iluwatar.abstractdocument;
import org.junit.jupiter.api.Test;
import static org.junit.jupiter.api.Assertions.assertDoesNotThrow;
/**
* Simple App test
*/
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.
*/
public class AppTest {
@Test
void shouldExecuteAppWithoutException() {
assertDoesNotThrow(() -> App.main(null));
public void shouldExecuteAppWithoutException() {
App.main(null);
}
}

View File

@ -9,19 +9,16 @@ tags:
---
## Also known as
Kit
## Intent
Provide an interface for creating families of related or dependent
objects without specifying their concrete classes.
## Explanation
Real world example
> 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.
> To create a kingdom we need objects with 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
@ -33,18 +30,15 @@ Wikipedia says
**Programmatic Example**
Translating the kingdom example above. First of all we have some interfaces and implementation for the objects in the
kingdom.
Translating the kingdom example above. First of all we have some interfaces and implementation for the objects in the kingdom
```java
public interface Castle {
String getDescription();
}
public interface King {
String getDescription();
}
public interface Army {
String getDescription();
}
@ -72,7 +66,7 @@ public class ElfArmy implements Army {
}
}
// Orcish implementations similarly -> ...
// Orcish implementations similarly...
```
@ -118,17 +112,9 @@ var castle = factory.createCastle();
var king = factory.createKing();
var army = factory.createArmy();
castle.getDescription();
king.getDescription();
army.getDescription();
```
Program output:
```java
This is the Elven castle!
This is the Elven king!
This is the Elven Army!
castle.getDescription(); // Output: This is the Elven castle!
king.getDescription(); // Output: This is the Elven king!
army.getDescription(); // Output: 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.
@ -170,52 +156,46 @@ public static void main(String[] args) {
```
## Class diagram
![alt text](./etc/abstract-factory.urm.png "Abstract Factory class diagram")
## Applicability
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 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.
* You need a run-time value to construct a particular dependency
* You want to decide which product to call from a family at runtime.
* You need to supply one or more parameters only known at run-time before you can resolve a dependency.
* When you need consistency among products
* You dont want to change existing code when adding new products or families of products to the program.
* a system should be independent of how its products are created, composed and represented
* a system should be configured with one of multiple families of products
* a 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.
* you need a run-time value to construct a particular dependency
* you want to decide which product to call from a family at runtime.
* you need to supply one or more parameters only known at run-time before you can resolve a dependency.
* when you need consistency among products
* you dont want to change existing code when adding new products or families of products to the program.
Example use cases
## Use Cases:
* Selecting to call to the appropriate implementation of FileSystemAcmeService or DatabaseAcmeService or NetworkAcmeService at runtime.
* Unit test case writing becomes much easier
* Selecting to call the appropriate implementation of FileSystemAcmeService or DatabaseAcmeService or NetworkAcmeService at runtime.
* Unit test case writing becomes much easier
* UI tools for different OS
## Consequences:
* Dependency injection in java hides the service class dependencies that can lead to runtime errors that would have been caught at compile time.
* Dependency injection in java hides the service class dependencies that can lead to runtime errors that would have been caught at compile time.
* While the pattern is great when creating predefined objects, adding the new ones might be challenging.
* 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 may become more complicated than it should be, since a lot of new interfaces and classes are introduced along with the pattern.
## Tutorial
* [Abstract Factory Pattern Tutorial](https://www.journaldev.com/1418/abstract-factory-design-pattern-in-java)
## Known uses
## Real world examples
* [javax.xml.parsers.DocumentBuilderFactory](http://docs.oracle.com/javase/8/docs/api/javax/xml/parsers/DocumentBuilderFactory.html)
* [javax.xml.transform.TransformerFactory](http://docs.oracle.com/javase/8/docs/api/javax/xml/transform/TransformerFactory.html#newInstance--)
* [javax.xml.xpath.XPathFactory](http://docs.oracle.com/javase/8/docs/api/javax/xml/xpath/XPathFactory.html#newInstance--)
## Related patterns
[Factory Method](https://java-design-patterns.com/patterns/factory-method/)
[Factory Kit](https://java-design-patterns.com/patterns/factory-kit/)
## Credits
* [Design Patterns: Elements of Reusable Object-Oriented Software](https://www.amazon.com/gp/product/0201633612/ref=as_li_tl?ie=UTF8&camp=1789&creative=9325&creativeASIN=0201633612&linkCode=as2&tag=javadesignpat-20&linkId=675d49790ce11db99d90bde47f1aeb59)

View File

@ -22,7 +22,7 @@
<parent>
<groupId>com.iluwatar</groupId>
<artifactId>java-design-patterns</artifactId>
<version>1.24.0-SNAPSHOT</version>
<version>1.23.0-SNAPSHOT</version>
</parent>
<artifactId>abstract-factory</artifactId>
<dependencies>

View File

@ -23,6 +23,7 @@
package com.iluwatar.abstractfactory;
import com.iluwatar.abstractfactory.App.FactoryMaker.KingdomType;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
@ -40,14 +41,84 @@ import org.slf4j.LoggerFactory;
* and its implementations ( {@link ElfKingdomFactory}, {@link OrcKingdomFactory}). The example uses
* both concrete implementations to create a king, a castle and an army.
*/
public class App implements Runnable {
public class App {
private static Logger log = LoggerFactory.getLogger(App.class);
private static final Logger LOGGER = LoggerFactory.getLogger(App.class);
private final Kingdom kingdom = new Kingdom();
private King king;
private Castle castle;
private Army army;
public Kingdom getKingdom() {
return kingdom;
/**
* Creates kingdom.
*/
public void createKingdom(final KingdomFactory factory) {
setKing(factory.createKing());
setCastle(factory.createCastle());
setArmy(factory.createArmy());
}
King getKing(final KingdomFactory factory) {
return factory.createKing();
}
public King getKing() {
return king;
}
private void setKing(final King king) {
this.king = king;
}
Castle getCastle(final KingdomFactory factory) {
return factory.createCastle();
}
public Castle getCastle() {
return castle;
}
private void setCastle(final Castle castle) {
this.castle = castle;
}
Army getArmy(final KingdomFactory factory) {
return factory.createArmy();
}
public Army getArmy() {
return army;
}
private void setArmy(final Army army) {
this.army = army;
}
/**
* The factory of kingdom factories.
*/
public static class FactoryMaker {
/**
* Enumeration for the different types of Kingdoms.
*/
public enum KingdomType {
ELF, ORC
}
/**
* The factory method to create KingdomFactory concrete objects.
*/
public static KingdomFactory makeFactory(KingdomType type) {
switch (type) {
case ELF:
return new ElfKingdomFactory();
case ORC:
return new OrcKingdomFactory();
default:
throw new IllegalArgumentException("KingdomType not supported.");
}
}
}
/**
@ -56,33 +127,19 @@ public class App implements Runnable {
* @param args command line args
*/
public static void main(String[] args) {
var app = new App();
app.run();
}
@Override
public void run() {
log.info("Elf Kingdom");
createKingdom(Kingdom.FactoryMaker.KingdomType.ELF);
log.info(kingdom.getArmy().getDescription());
log.info(kingdom.getCastle().getDescription());
log.info(kingdom.getKing().getDescription());
LOGGER.info("Elf Kingdom");
app.createKingdom(FactoryMaker.makeFactory(KingdomType.ELF));
LOGGER.info(app.getArmy().getDescription());
LOGGER.info(app.getCastle().getDescription());
LOGGER.info(app.getKing().getDescription());
log.info("Orc Kingdom");
createKingdom(Kingdom.FactoryMaker.KingdomType.ORC);
log.info(kingdom.getArmy().getDescription());
log.info(kingdom.getCastle().getDescription());
log.info(kingdom.getKing().getDescription());
}
/**
* Creates kingdom.
* @param kingdomType type of Kingdom
*/
public void createKingdom(final Kingdom.FactoryMaker.KingdomType kingdomType) {
final KingdomFactory kingdomFactory = Kingdom.FactoryMaker.makeFactory(kingdomType);
kingdom.setKing(kingdomFactory.createKing());
kingdom.setCastle(kingdomFactory.createCastle());
kingdom.setArmy(kingdomFactory.createArmy());
LOGGER.info("Orc Kingdom");
app.createKingdom(FactoryMaker.makeFactory(KingdomType.ORC));
LOGGER.info(app.getArmy().getDescription());
LOGGER.info(app.getCastle().getDescription());
LOGGER.info(app.getKing().getDescription());
}
}

View File

@ -1,82 +0,0 @@
/*
* The MIT License
* Copyright © 2014-2019 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.abstractfactory;
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.
*/
public static class FactoryMaker {
/**
* Enumeration for the different types of Kingdoms.
*/
public enum KingdomType {
ELF, ORC
}
/**
* The factory method to create KingdomFactory concrete objects.
*/
public static KingdomFactory makeFactory(KingdomType type) {
switch (type) {
case ELF:
return new ElfKingdomFactory();
case ORC:
return new OrcKingdomFactory();
default:
throw new IllegalArgumentException("KingdomType not supported.");
}
}
}
}

View File

@ -21,13 +21,6 @@
* THE SOFTWARE.
*/
package com.iluwatar.factory;
/**
* Car interface.
*/
public interface Car {
String getDescription();
}
module com.iluwatar.abstractfactory {
requires org.slf4j;
}

View File

@ -23,71 +23,65 @@
package com.iluwatar.abstractfactory;
import org.junit.jupiter.api.Test;
import static org.junit.jupiter.api.Assertions.assertEquals;
import static org.junit.jupiter.api.Assertions.assertTrue;
import com.iluwatar.abstractfactory.App.FactoryMaker;
import com.iluwatar.abstractfactory.App.FactoryMaker.KingdomType;
import org.junit.jupiter.api.BeforeEach;
import org.junit.jupiter.api.Test;
/**
* Test for abstract factory.
*/
public class AbstractFactoryTest {
private final App app = new App();
private App app = new App();
private KingdomFactory elfFactory;
private KingdomFactory orcFactory;
@BeforeEach
public void setUp() {
elfFactory = FactoryMaker.makeFactory(KingdomType.ELF);
orcFactory = FactoryMaker.makeFactory(KingdomType.ORC);
}
@Test
public void king() {
app.createKingdom(Kingdom.FactoryMaker.KingdomType.ELF);
final var kingdom = app.getKingdom();
final var elfKing = kingdom.getKing();
final var elfKing = app.getKing(elfFactory);
assertTrue(elfKing instanceof ElfKing);
assertEquals(ElfKing.DESCRIPTION, elfKing.getDescription());
app.createKingdom(Kingdom.FactoryMaker.KingdomType.ORC);
final var orcKing = kingdom.getKing();
final var orcKing = app.getKing(orcFactory);
assertTrue(orcKing instanceof OrcKing);
assertEquals(OrcKing.DESCRIPTION, orcKing.getDescription());
}
@Test
public void castle() {
app.createKingdom(Kingdom.FactoryMaker.KingdomType.ELF);
final var kingdom = app.getKingdom();
final var elfCastle = kingdom.getCastle();
final var elfCastle = app.getCastle(elfFactory);
assertTrue(elfCastle instanceof ElfCastle);
assertEquals(ElfCastle.DESCRIPTION, elfCastle.getDescription());
app.createKingdom(Kingdom.FactoryMaker.KingdomType.ORC);
final var orcCastle = kingdom.getCastle();
final var orcCastle = app.getCastle(orcFactory);
assertTrue(orcCastle instanceof OrcCastle);
assertEquals(OrcCastle.DESCRIPTION, orcCastle.getDescription());
}
@Test
public void army() {
app.createKingdom(Kingdom.FactoryMaker.KingdomType.ELF);
final var kingdom = app.getKingdom();
final var elfArmy = kingdom.getArmy();
final var elfArmy = app.getArmy(elfFactory);
assertTrue(elfArmy instanceof ElfArmy);
assertEquals(ElfArmy.DESCRIPTION, elfArmy.getDescription());
app.createKingdom(Kingdom.FactoryMaker.KingdomType.ORC);
final var orcArmy = kingdom.getArmy();
final var orcArmy = app.getArmy(orcFactory);
assertTrue(orcArmy instanceof OrcArmy);
assertEquals(OrcArmy.DESCRIPTION, orcArmy.getDescription());
}
@Test
public void createElfKingdom() {
app.createKingdom(Kingdom.FactoryMaker.KingdomType.ELF);
final var kingdom = app.getKingdom();
final var king = kingdom.getKing();
final var castle = kingdom.getCastle();
final var army = kingdom.getArmy();
app.createKingdom(elfFactory);
final var king = app.getKing();
final var castle = app.getCastle();
final var army = app.getArmy();
assertTrue(king instanceof ElfKing);
assertEquals(ElfKing.DESCRIPTION, king.getDescription());
assertTrue(castle instanceof ElfCastle);
@ -98,12 +92,10 @@ public class AbstractFactoryTest {
@Test
public void createOrcKingdom() {
app.createKingdom(Kingdom.FactoryMaker.KingdomType.ORC);
final var kingdom = app.getKingdom();
final var king = kingdom.getKing();
final var castle = kingdom.getCastle();
final var army = kingdom.getArmy();
app.createKingdom(orcFactory);
final var king = app.getKing();
final var castle = app.getCastle();
final var army = app.getArmy();
assertTrue(king instanceof OrcKing);
assertEquals(OrcKing.DESCRIPTION, king.getDescription());
assertTrue(castle instanceof OrcCastle);

View File

@ -25,23 +25,12 @@ package com.iluwatar.abstractfactory;
import org.junit.jupiter.api.Test;
import static org.junit.jupiter.api.Assertions.assertDoesNotThrow;
/**
* 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.
*/
public class AppTest {
@Test
void shouldExecuteApplicationWithoutException() {
assertDoesNotThrow(() -> App.main(new String[]{}));
public void test() {
App.main(new String[]{});
}
}

View File

@ -9,126 +9,12 @@ tags:
---
## Intent
Allow new functions to be added to existing class hierarchies without affecting those hierarchies, and without creating
the troublesome dependency cycles that are inherent to the GoF Visitor Pattern.
## Explanation
Real world example
> We have a hierarchy of modem classes. The modems in this hierarchy need to be visited by an external algorithm based
> on filtering criteria (is it Unix or DOS compatible modem).
In plain words
> Acyclic Visitor allows functions to be added to existing class hierarchies without modifying the hierarchies.
[WikiWikiWeb](https://wiki.c2.com/?AcyclicVisitor) says
> The Acyclic Visitor pattern allows new functions to be added to existing class hierarchies without affecting those
> hierarchies, and without creating the dependency cycles that are inherent to the GangOfFour VisitorPattern.
**Programmatic Example**
Here's the `Modem` hierarchy.
```java
public abstract class Modem {
public abstract void accept(ModemVisitor modemVisitor);
}
public class Zoom extends Modem {
...
@Override
public void accept(ModemVisitor modemVisitor) {
if (modemVisitor instanceof ZoomVisitor) {
((ZoomVisitor) modemVisitor).visit(this);
} else {
LOGGER.info("Only ZoomVisitor is allowed to visit Zoom modem");
}
}
}
public class Hayes extends Modem {
...
@Override
public void accept(ModemVisitor modemVisitor) {
if (modemVisitor instanceof HayesVisitor) {
((HayesVisitor) modemVisitor).visit(this);
} else {
LOGGER.info("Only HayesVisitor is allowed to visit Hayes modem");
}
}
}
```
Next we introduce the `ModemVisitor` hierarchy.
```java
public interface ModemVisitor {
}
public interface HayesVisitor extends ModemVisitor {
void visit(Hayes hayes);
}
public interface ZoomVisitor extends ModemVisitor {
void visit(Zoom zoom);
}
public interface AllModemVisitor extends ZoomVisitor, HayesVisitor {
}
public class ConfigureForDosVisitor implements AllModemVisitor {
...
@Override
public void visit(Hayes hayes) {
LOGGER.info(hayes + " used with Dos configurator.");
}
@Override
public void visit(Zoom zoom) {
LOGGER.info(zoom + " used with Dos configurator.");
}
}
public class ConfigureForUnixVisitor implements ZoomVisitor {
...
@Override
public void visit(Zoom zoom) {
LOGGER.info(zoom + " used with Unix configurator.");
}
}
```
Finally, here are the visitors in action.
```java
var conUnix = new ConfigureForUnixVisitor();
var conDos = new ConfigureForDosVisitor();
var zoom = new Zoom();
var hayes = new Hayes();
hayes.accept(conDos);
zoom.accept(conDos);
hayes.accept(conUnix);
zoom.accept(conUnix);
```
Program output:
```
// Hayes modem used with Dos configurator.
// Zoom modem used with Dos configurator.
// Only HayesVisitor is allowed to visit Hayes modem
// Zoom modem used with Unix configurator.
```
Allow new functions to be added to existing class hierarchies without affecting those hierarchies, and without creating the troublesome dependency cycles that are inherent to the GOF VISITOR Pattern.
## Class diagram
![alt text](./etc/acyclic-visitor.png "Acyclic Visitor")
## Applicability
This pattern can be used:
* When you need to add a new function to an existing hierarchy without the need to alter or affect that hierarchy.
@ -138,7 +24,6 @@ This pattern can be used:
* When the recompilation, relinking, retesting or redistribution of the derivatives of Element is very expensive.
## Consequences
The good:
* No dependency cycles between class hierarchies.
@ -147,14 +32,11 @@ The good:
The bad:
* Violates [Liskov's Substitution Principle](https://java-design-patterns.com/principles/#liskov-substitution-principle) by showing that it can accept all visitors but actually only being interested in particular visitors.
* Violates the principle of least surprise or Liskov's Substitution principle by showing that it can accept all visitors but actually only being interested in particular visitors.
* Parallel hierarchy of visitors has to be created for all members in visitable class hierarchy.
## Related patterns
* [Visitor Pattern](https://java-design-patterns.com/patterns/visitor/)
* [Visitor Pattern](../visitor/)
## Credits
* [Acyclic Visitor by Robert C. Martin](http://condor.depaul.edu/dmumaugh/OOT/Design-Principles/acv.pdf)
* [Acyclic Visitor in WikiWikiWeb](https://wiki.c2.com/?AcyclicVisitor)
* [Acyclic Visitor](http://condor.depaul.edu/dmumaugh/OOT/Design-Principles/acv.pdf)

View File

@ -0,0 +1,115 @@
<?xml version="1.0" encoding="UTF-8"?>
<class-diagram version="1.2.2" icons="true" always-add-relationships="false" generalizations="true" realizations="true"
associations="true" dependencies="false" nesting-relationships="true" router="FAN">
<interface id="1" language="java" name="com.iluwatar.acyclicvisitor.ModemVisitor" project="acyclic-visitor"
file="/acyclic-visitor/src/main/java/com/iluwatar/acyclicvisitor/ModemVisitor.java" binary="false"
corner="BOTTOM_RIGHT">
<position height="-1" width="-1" x="860" y="67"/>
<display autosize="true" stereotype="true" package="true" initial-value="false" signature="true"
sort-features="false" accessors="true" visibility="true">
<attributes public="true" package="true" protected="true" private="true" static="true"/>
<operations public="true" package="true" protected="true" private="true" static="true"/>
</display>
</interface>
<class id="2" language="java" name="com.iluwatar.acyclicvisitor.Modem" project="acyclic-visitor"
file="/acyclic-visitor/src/main/java/com/iluwatar/acyclicvisitor/Modem.java" binary="false" corner="BOTTOM_RIGHT">
<position height="-1" width="-1" x="327" y="77"/>
<display autosize="true" stereotype="true" package="true" initial-value="false" signature="true"
sort-features="false" accessors="true" visibility="true">
<attributes public="true" package="true" protected="true" private="true" static="true"/>
<operations public="true" package="true" protected="true" private="true" static="true"/>
</display>
</class>
<class id="3" language="java" name="com.iluwatar.acyclicvisitor.ConfigureForUnixVisitor" project="acyclic-visitor"
file="/acyclic-visitor/src/main/java/com/iluwatar/acyclicvisitor/ConfigureForUnixVisitor.java" binary="false"
corner="BOTTOM_RIGHT">
<position height="124" width="196" x="647" y="225"/>
<display autosize="true" stereotype="true" package="true" initial-value="false" signature="true"
sort-features="false" accessors="true" visibility="true">
<attributes public="true" package="true" protected="true" private="true" static="true"/>
<operations public="true" package="true" protected="true" private="true" static="true"/>
</display>
</class>
<class id="4" language="java" name="com.iluwatar.acyclicvisitor.Zoom" project="acyclic-visitor"
file="/acyclic-visitor/src/main/java/com/iluwatar/acyclicvisitor/Zoom.java" binary="false" corner="BOTTOM_RIGHT">
<position height="-1" width="-1" x="203" y="305"/>
<display autosize="true" stereotype="true" package="true" initial-value="false" signature="true"
sort-features="false" accessors="true" visibility="true">
<attributes public="true" package="true" protected="true" private="true" static="true"/>
<operations public="true" package="true" protected="true" private="true" static="true"/>
</display>
</class>
<interface id="5" language="java" name="com.iluwatar.acyclicvisitor.HayesVisitor" project="acyclic-visitor"
file="/acyclic-visitor/src/main/java/com/iluwatar/acyclicvisitor/HayesVisitor.java" binary="false"
corner="BOTTOM_RIGHT">
<position height="-1" width="-1" x="1019" y="468"/>
<display autosize="true" stereotype="true" package="true" initial-value="false" signature="true"
sort-features="false" accessors="true" visibility="true">
<attributes public="true" package="true" protected="true" private="true" static="true"/>
<operations public="true" package="true" protected="true" private="true" static="true"/>
</display>
</interface>
<interface id="6" language="java" name="com.iluwatar.acyclicvisitor.ZoomVisitor" project="acyclic-visitor"
file="/acyclic-visitor/src/main/java/com/iluwatar/acyclicvisitor/ZoomVisitor.java" binary="false"
corner="BOTTOM_RIGHT">
<position height="-1" width="-1" x="758" y="467"/>
<display autosize="true" stereotype="true" package="true" initial-value="false" signature="true"
sort-features="false" accessors="true" visibility="true">
<attributes public="true" package="true" protected="true" private="true" static="true"/>
<operations public="true" package="true" protected="true" private="true" static="true"/>
</display>
</interface>
<class id="7" language="java" name="com.iluwatar.acyclicvisitor.Hayes" project="acyclic-visitor"
file="/acyclic-visitor/src/main/java/com/iluwatar/acyclicvisitor/Hayes.java" binary="false" corner="BOTTOM_RIGHT">
<position height="-1" width="-1" x="479" y="307"/>
<display autosize="true" stereotype="true" package="true" initial-value="false" signature="true"
sort-features="false" accessors="true" visibility="true">
<attributes public="true" package="true" protected="true" private="true" static="true"/>
<operations public="true" package="true" protected="true" private="true" static="true"/>
</display>
</class>
<class id="8" language="java" name="com.iluwatar.acyclicvisitor.ConfigureForDosVisitor" project="acyclic-visitor"
file="/acyclic-visitor/src/main/java/com/iluwatar/acyclicvisitor/ConfigureForDosVisitor.java" binary="false"
corner="BOTTOM_RIGHT">
<position height="142" width="192" x="883" y="225"/>
<display autosize="true" stereotype="true" package="true" initial-value="false" signature="true"
sort-features="false" accessors="true" visibility="true">
<attributes public="true" package="true" protected="true" private="true" static="true"/>
<operations public="true" package="true" protected="true" private="true" static="true"/>
</display>
</class>
<generalization id="9">
<end type="SOURCE" refId="7"/>
<end type="TARGET" refId="2"/>
</generalization>
<realization id="10">
<end type="SOURCE" refId="8"/>
<end type="TARGET" refId="6"/>
</realization>
<realization id="11">
<end type="SOURCE" refId="8"/>
<end type="TARGET" refId="5"/>
</realization>
<realization id="12">
<end type="SOURCE" refId="3"/>
<end type="TARGET" refId="6"/>
</realization>
<realization id="13">
<end type="SOURCE" refId="3"/>
<end type="TARGET" refId="1"/>
</realization>
<realization id="14">
<end type="SOURCE" refId="8"/>
<end type="TARGET" refId="1"/>
</realization>
<generalization id="15">
<end type="SOURCE" refId="4"/>
<end type="TARGET" refId="2"/>
</generalization>
<classifier-display autosize="true" stereotype="true" package="true" initial-value="false" signature="true"
sort-features="false" accessors="true" visibility="true">
<attributes public="true" package="true" protected="true" private="true" static="true"/>
<operations public="true" package="true" protected="true" private="true" static="true"/>
</classifier-display>
<association-display labels="true" multiplicity="true"/>
</class-diagram>

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@ -21,7 +21,7 @@
<parent>
<groupId>com.iluwatar</groupId>
<artifactId>java-design-patterns</artifactId>
<version>1.24.0-SNAPSHOT</version>
<version>1.23.0-SNAPSHOT</version>
</parent>
<artifactId>acyclic-visitor</artifactId>

View File

@ -21,10 +21,6 @@
* THE SOFTWARE.
*/
package com.iluwatar.separatedinterface.invoice;
public interface TaxCalculator {
double calculate(double amount);
}
module com.iluwatar.acyclicvisitor {
requires org.slf4j;
}

View File

@ -25,23 +25,13 @@ package com.iluwatar.acyclicvisitor;
import org.junit.jupiter.api.Test;
import static org.junit.jupiter.api.Assertions.assertDoesNotThrow;
/**
* Tests that the Acyclic Visitor 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.
*/
public class AppTest {
@Test
void shouldExecuteApplicationWithoutException() {
assertDoesNotThrow(() -> App.main(new String[]{}));
public void test() {
App.main(new String[]{});
}
}

View File

@ -37,7 +37,7 @@ import uk.org.lidalia.slf4jtest.TestLoggerFactory;
*/
public class ConfigureForDosVisitorTest {
private final TestLogger logger = TestLoggerFactory.getTestLogger(ConfigureForDosVisitor.class);
private TestLogger logger = TestLoggerFactory.getTestLogger(ConfigureForDosVisitor.class);
@Test
public void testVisitForZoom() {

View File

@ -12,8 +12,9 @@ tags:
Wrapper
## Intent
Convert the interface of a class into another interface the clients expect. Adapter lets classes work together that
couldn't otherwise because of incompatible interfaces.
Convert the interface of a class into another interface the clients
expect. Adapter lets classes work together that couldn't otherwise because of
incompatible interfaces.
## Explanation
@ -55,7 +56,7 @@ And captain expects an implementation of `RowingBoat` interface to be able to mo
```java
public class Captain {
private final RowingBoat rowingBoat;
private RowingBoat rowingBoat;
// default constructor and setter for rowingBoat
public Captain(RowingBoat rowingBoat) {
this.rowingBoat = rowingBoat;
@ -74,7 +75,7 @@ public class FishingBoatAdapter implements RowingBoat {
private static final Logger LOGGER = LoggerFactory.getLogger(FishingBoatAdapter.class);
private final FishingBoat boat;
private FishingBoat boat;
public FishingBoatAdapter() {
boat = new FishingBoat();

View File

@ -22,7 +22,7 @@
<parent>
<groupId>com.iluwatar</groupId>
<artifactId>java-design-patterns</artifactId>
<version>1.24.0-SNAPSHOT</version>
<version>1.23.0-SNAPSHOT</version>
</parent>
<artifactId>adapter</artifactId>
<dependencies>

View File

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

View File

@ -25,23 +25,12 @@ package com.iluwatar.adapter;
import org.junit.jupiter.api.Test;
import static org.junit.jupiter.api.Assertions.assertDoesNotThrow;
/**
* Tests that Adapter 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.
*/
public class AppTest {
@Test
void shouldExecuteApplicationWithoutException() {
assertDoesNotThrow(() -> App.main(new String[]{}));
public void test() {
App.main(new String[]{});
}
}

View File

@ -6,97 +6,20 @@ permalink: /patterns/aggregator-microservices/
categories: Architectural
tags:
- Cloud distributed
- Decoupling
- Microservices
---
## Intent
The user makes a single call to the aggregator service, and the aggregator then calls each relevant microservice.
## Explanation
Real world example
> Our web marketplace needs information about products and their current inventory. It makes a call to an aggregator
> service which in turn calls the product information microservice and product inventory microservice returning the
> combined information.
In plain words
> Aggregator Microservice collects pieces of data from various microservices and returns an aggregate for processing.
Stack Overflow says
> Aggregator Microservice invokes multiple services to achieve the functionality required by the application.
**Programmatic Example**
Let's start from the data model. Here's our `Product`.
```java
public class Product {
private String title;
private int productInventories;
// getters and setters ->
...
}
```
Next we can introduce our `Aggregator` microservice. It contains clients `ProductInformationClient` and
`ProductInventoryClient` for calling respective microservices.
```java
@RestController
public class Aggregator {
@Resource
private ProductInformationClient informationClient;
@Resource
private ProductInventoryClient inventoryClient;
@RequestMapping(path = "/product", method = RequestMethod.GET)
public Product getProduct() {
var product = new Product();
var productTitle = informationClient.getProductTitle();
var productInventory = inventoryClient.getProductInventories();
//Fallback to error message
product.setTitle(requireNonNullElse(productTitle, "Error: Fetching Product Title Failed"));
//Fallback to default error inventory
product.setProductInventories(requireNonNullElse(productInventory, -1));
return product;
}
}
```
Here's the essence of information microservice implementation. Inventory microservice is similar, it just returns
inventory counts.
```java
@RestController
public class InformationController {
@RequestMapping(value = "/information", method = RequestMethod.GET)
public String getProductTitle() {
return "The Product Title.";
}
}
```
Now calling our `Aggregator` REST API returns the product information.
```bash
curl http://localhost:50004/product
{"title":"The Product Title.","productInventories":5}
```
The user makes a single call to the Aggregator, and the aggregator then calls each relevant microservice and collects
the data, apply business logic to it, and further publish is as a REST Endpoint.
More variations of the aggregator are:
- Proxy Microservice Design Pattern: A different microservice is called upon the business need.
- Chained Microservice Design Pattern: In this case each microservice is dependent/ chained to a series
of other microservices.
## Class diagram
![alt text](./aggregator-service/etc/aggregator-service.png "Aggregator Microservice")
![alt text](./etc/aggregator-microservice.png "Aggregator Microservice")
## Applicability
@ -105,5 +28,3 @@ Use the Aggregator Microservices pattern when you need a unified API for various
## Credits
* [Microservice Design Patterns](http://web.archive.org/web/20190705163602/http://blog.arungupta.me/microservice-design-patterns/)
* [Microservices Patterns: With examples in Java](https://www.amazon.com/gp/product/1617294543/ref=as_li_qf_asin_il_tl?ie=UTF8&tag=javadesignpat-20&creative=9325&linkCode=as2&creativeASIN=1617294543&linkId=8b4e570267bc5fb8b8189917b461dc60)
* [Architectural Patterns: Uncover essential patterns in the most indispensable realm of enterprise architecture](https://www.amazon.com/gp/product/B077T7V8RC/ref=as_li_qf_asin_il_tl?ie=UTF8&tag=javadesignpat-20&creative=9325&linkCode=as2&creativeASIN=B077T7V8RC&linkId=c34d204bfe1b277914b420189f09c1a4)

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@ -20,7 +20,7 @@
<parent>
<artifactId>aggregator-microservices</artifactId>
<groupId>com.iluwatar</groupId>
<version>1.24.0-SNAPSHOT</version>
<version>1.23.0-SNAPSHOT</version>
</parent>
<modelVersion>4.0.0</modelVersion>
<artifactId>aggregator-service</artifactId>

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@ -20,7 +20,7 @@
<parent>
<artifactId>aggregator-microservices</artifactId>
<groupId>com.iluwatar</groupId>
<version>1.24.0-SNAPSHOT</version>
<version>1.23.0-SNAPSHOT</version>
</parent>
<modelVersion>4.0.0</modelVersion>

View File

@ -20,7 +20,7 @@
<parent>
<artifactId>aggregator-microservices</artifactId>
<groupId>com.iluwatar</groupId>
<version>1.24.0-SNAPSHOT</version>
<version>1.23.0-SNAPSHOT</version>
</parent>
<modelVersion>4.0.0</modelVersion>
<artifactId>inventory-microservice</artifactId>

View File

@ -29,7 +29,7 @@
<parent>
<artifactId>java-design-patterns</artifactId>
<groupId>com.iluwatar</groupId>
<version>1.24.0-SNAPSHOT</version>
<version>1.23.0-SNAPSHOT</version>
</parent>
<modelVersion>4.0.0</modelVersion>
<artifactId>aggregator-microservices</artifactId>

View File

@ -10,37 +10,28 @@ tags:
---
## Intent
Provide a helper service instance on a client and offload common functionality away from a shared resource.
## Explanation
Real world example
> A remote service has many clients accessing a function it provides. The service is a legacy application and is
> impossible to update. Large numbers of requests from users are causing connectivity issues. New rules for request
> frequency should be implemented along with latency checks and client-side logging.
> A remote service has many clients accessing a function it provides. The service is a legacy application and is impossible to update. Large numbers of requests from users are causing connectivity issues. New rules for request frequency should be implemented along with latency checks and client-side logging.
In plain words
> With the Ambassador pattern, we can implement less-frequent polling from clients along with latency checks and
> logging.
> Using the ambassador pattern, we can implement less-frequent polling from clients along with latency checks and logging.
Microsoft documentation states
> An ambassador service can be thought of as an out-of-process proxy which is co-located with the client. This pattern
> can be useful for offloading common client connectivity tasks such as monitoring, logging, routing,
> security (such as TLS), and resiliency patterns in a language agnostic way. It is often used with legacy applications,
> or other applications that are difficult to modify, in order to extend their networking capabilities. It can also
> enable a specialized team to implement those features.
> An ambassador service can be thought of as an out-of-process proxy that is co-located with the client. This pattern can be useful for offloading common client connectivity tasks such as monitoring, logging, routing, security (such as TLS), and resiliency patterns in a language agnostic way. It is often used with legacy applications, or other applications that are difficult to modify, in order to extend their networking capabilities. It can also enable a specialized team to implement those features.
**Programmatic Example**
With the above introduction in mind we will imitate the functionality in this example. We have an interface implemented
by the remote service as well as the ambassador service:
With the above example in mind we will imitate the functionality in a simple manner. We have an interface implemented by the remote service as well as the ambassador service:
```java
interface RemoteServiceInterface {
long doRemoteFunction(int value) throws Exception;
}
```
@ -145,7 +136,7 @@ public class Client {
}
```
Here are two clients using the service.
And here are two clients using the service.
```java
public class App {
@ -158,29 +149,13 @@ public class App {
}
```
Here's the output for running the example:
```java
Time taken (ms): 111
Service result: 120
Time taken (ms): 931
Failed to reach remote: (1)
Time taken (ms): 665
Failed to reach remote: (2)
Time taken (ms): 538
Failed to reach remote: (3)
Service result: -1
```
## Class diagram
![alt text](./etc/ambassador.urm.png "Ambassador class diagram")
## Applicability
Ambassador is applicable when working with a legacy remote service which cannot be modified or would be extremely
difficult to modify. Connectivity features can be implemented on the client avoiding the need for changes on the remote
service.
Ambassador is applicable when working with a legacy remote service that cannot
be modified or would be extremely difficult to modify. Connectivity features can
be implemented on the client avoiding the need for changes on the remote service.
* Ambassador provides a local interface for a remote service.
* Ambassador provides logging, circuit breaking, retries and security on the client.
@ -193,14 +168,10 @@ service.
* Offload remote service tasks
* Facilitate network connection
## Known uses
## Real world examples
* [Kubernetes-native API gateway for microservices](https://github.com/datawire/ambassador)
## Related patterns
* [Proxy](https://java-design-patterns.com/patterns/proxy/)
## Credits
* [Ambassador pattern](https://docs.microsoft.com/en-us/azure/architecture/patterns/ambassador)

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@ -20,7 +20,7 @@
<parent>
<artifactId>java-design-patterns</artifactId>
<groupId>com.iluwatar</groupId>
<version>1.24.0-SNAPSHOT</version>
<version>1.23.0-SNAPSHOT</version>
</parent>
<modelVersion>4.0.0</modelVersion>
<artifactId>ambassador</artifactId>

View File

@ -62,7 +62,7 @@ public class RemoteService implements RemoteServiceInterface {
*
* @param value integer value to be multiplied.
* @return if waitTime is less than {@link RemoteService#THRESHOLD}, it returns value * 10,
* otherwise {@link RemoteServiceStatus#FAILURE}.
* otherwise {@link RemoteServiceInterface#FAILURE}.
*/
@Override
public long doRemoteFunction(int value) {
@ -74,7 +74,6 @@ public class RemoteService implements RemoteServiceInterface {
} catch (InterruptedException e) {
LOGGER.error("Thread sleep state interrupted", e);
}
return waitTime <= THRESHOLD ? value * 10
: RemoteServiceStatus.FAILURE.getRemoteServiceStatusValue();
return waitTime <= THRESHOLD ? value * 10 : FAILURE;
}
}

View File

@ -27,6 +27,7 @@ package com.iluwatar.ambassador;
* Interface shared by ({@link RemoteService}) and ({@link ServiceAmbassador}).
*/
interface RemoteServiceInterface {
int FAILURE = -1;
long doRemoteFunction(int value);
long doRemoteFunction(int value) throws Exception;
}

View File

@ -1,48 +0,0 @@
/*
* The MIT License
* Copyright © 2014-2019 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.ambassador;
/**
* Holds information regarding the status of the Remote Service.
*
* <p> This Enum replaces the integer value previously
* stored in {@link RemoteServiceInterface} as SonarCloud was identifying
* it as an issue. All test cases have been checked after changes,
* without failures. </p>
*/
public enum RemoteServiceStatus {
FAILURE(-1)
;
private final long remoteServiceStatusValue;
RemoteServiceStatus(long remoteServiceStatusValue) {
this.remoteServiceStatusValue = remoteServiceStatusValue;
}
public long getRemoteServiceStatusValue() {
return remoteServiceStatusValue;
}
}

View File

@ -23,7 +23,6 @@
package com.iluwatar.ambassador;
import static com.iluwatar.ambassador.RemoteServiceStatus.FAILURE;
import static java.lang.Thread.sleep;
import org.slf4j.Logger;
@ -59,14 +58,14 @@ public class ServiceAmbassador implements RemoteServiceInterface {
private long safeCall(int value) {
var retries = 0;
var result = FAILURE.getRemoteServiceStatusValue();
var result = (long) FAILURE;
for (int i = 0; i < RETRIES; i++) {
if (retries >= RETRIES) {
return FAILURE.getRemoteServiceStatusValue();
return FAILURE;
}
if ((result = checkLatency(value)) == FAILURE.getRemoteServiceStatusValue()) {
if ((result = checkLatency(value)) == FAILURE) {
LOGGER.info("Failed to reach remote: (" + (i + 1) + ")");
retries++;
try {

View File

@ -25,23 +25,13 @@ package com.iluwatar.ambassador;
import org.junit.jupiter.api.Test;
import static org.junit.jupiter.api.Assertions.assertDoesNotThrow;
/**
* Application test
*/
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[]{}));
void test() {
App.main(new String[]{});
}
}

View File

@ -37,6 +37,6 @@ class ClientTest {
Client client = new Client();
var result = client.useService(10);
assertTrue(result == 100 || result == RemoteServiceStatus.FAILURE.getRemoteServiceStatusValue());
assertTrue(result == 100 || result == RemoteService.FAILURE);
}
}

View File

@ -37,7 +37,7 @@ class RemoteServiceTest {
void testFailedCall() {
var remoteService = new RemoteService(new StaticRandomProvider(0.21));
var result = remoteService.doRemoteFunction(10);
assertEquals(RemoteServiceStatus.FAILURE.getRemoteServiceStatusValue(), result);
assertEquals(RemoteServiceInterface.FAILURE, result);
}
@Test
@ -48,7 +48,7 @@ class RemoteServiceTest {
}
private static class StaticRandomProvider implements RandomProvider {
private final double value;
private double value;
StaticRandomProvider(double value) {
this.value = value;

View File

@ -35,6 +35,6 @@ class ServiceAmbassadorTest {
@Test
void test() {
long result = new ServiceAmbassador().doRemoteFunction(10);
assertTrue(result == 100 || result == RemoteServiceStatus.FAILURE.getRemoteServiceStatusValue());
assertTrue(result == 100 || result == RemoteServiceInterface.FAILURE);
}
}

View File

@ -12,53 +12,49 @@ tags:
## Intent
Aggregate calls to microservices in a single location, the API Gateway. The user makes a single call
to the API Gateway, and the API Gateway then calls each relevant microservice.
Aggregate calls to microservices in a single location: the API Gateway. The user makes a single call to the API Gateway,
and the API Gateway then calls each relevant microservice.
## Explanation
With the Microservices pattern, a client may need data from multiple different microservices. If the
client called each microservice directly, that could contribute to longer load times, since the
client would have to make a network request for each microservice called. Moreover, having the
client call each microservice directly ties the client to that microservice - if the internal
implementations of the microservices change (for example, if two microservices are combined sometime
in the future) or if the location (host and port) of a microservice changes, then every client that
With the Microservices pattern, a client may need data from multiple different microservices. If the client called each
microservice directly, that could contribute to longer load times, since the client would have to make a network request
for each microservice called. Moreover, having the client call each microservice directly ties the client to that
microservice - if the internal implementations of the microservices change (for example, if two microservices are
combined sometime in the future) or if the location (host and port) of a microservice changes, then every client that
makes use of those microservices must be updated.
The intent of the API Gateway pattern is to alleviate some of these issues. In the API Gateway
pattern, an additional entity (the API Gateway) is placed between the client and the microservices.
The job of the API Gateway is to aggregate the calls to the microservices. Rather than the client
calling each microservice individually, the client calls the API Gateway a single time. The API
Gateway then calls each of the microservices that the client needs.
The intent of the API Gateway pattern is to alleviate some of these issues. In the API Gateway pattern, an additional
entity (the API Gateway) is placed between the client and the microservices. The job of the API Gateway is to aggregate
the calls to the microservices. Rather than the client calling each microservice individually, the client calls the
API Gateway a single time. The API Gateway then calls each of the microservices that the client needs.
Real world example
> We are implementing microservices and API Gateway pattern for an e-commerce site. In this system
> the API Gateway makes calls to the Image and Price microservices.
> We are implementing microservices and API Gateway pattern for an e-commerce site. In this system the API Gateway makes
calls to the Image and Price microservices.
In plain words
> For a system implemented using microservices architecture, API Gateway is the single entry point
> that aggregates the calls to the individual microservices.
> For a system implemented using microservices architecture, API Gateway is the single entry point that aggregates the
calls to the individual microservices.
Wikipedia says
> API Gateway is a server that acts as an API front-end, receives API requests, enforces throttling
> and security policies, passes requests to the back-end service and then passes the response back
> to the requester. A gateway often includes a transformation engine to orchestrate and modify the
> requests and responses on the fly. A gateway can also provide functionality such as collecting
> analytics data and providing caching. The gateway can provide functionality to support
> authentication, authorization, security, audit and regulatory compliance.
> API Gateway is a server that acts as an API front-end, receives API requests, enforces throttling and security
policies, passes requests to the back-end service and then passes the response back to the requester. A gateway often
includes a transformation engine to orchestrate and modify the requests and responses on the fly. A gateway can also
provide functionality such as collecting analytics data and providing caching. The gateway can provide functionality to
support authentication, authorization, security, audit and regulatory compliance.
**Programmatic Example**
This implementation shows what the API Gateway pattern could look like for an e-commerce site. The
`ApiGateway` makes calls to the Image and Price microservices using the `ImageClientImpl` and
`PriceClientImpl` respectively. Customers viewing the site on a desktop device can see both price
information and an image of a product, so the `ApiGateway` calls both of the microservices and
aggregates the data in the `DesktopProduct` model. However, mobile users only see price information;
they do not see a product image. For mobile users, the `ApiGateway` only retrieves price
information, which it uses to populate the `MobileProduct`.
This implementation shows what the API Gateway pattern could look like for an e-commerce site. The `ApiGateway` makes
calls to the Image and Price microservices using the `ImageClientImpl` and `PriceClientImpl` respectively. Customers
viewing the site on a desktop device can see both price information and an image of a product, so the `ApiGateway` calls
both of the microservices and aggregates the data in the `DesktopProduct` model. However, mobile users only see price
information; they do not see a product image. For mobile users, the `ApiGateway` only retrieves price information, which
it uses to populate the `MobileProduct`.
Here's the Image microservice implementation.
@ -68,6 +64,7 @@ public interface ImageClient {
}
public class ImageClientImpl implements ImageClient {
@Override
public String getImagePath() {
var httpClient = HttpClient.newHttpClient();
@ -117,7 +114,7 @@ public class PriceClientImpl implements PriceClient {
}
```
Here we can see how API Gateway maps the requests to the microservices.
And here we can see how API Gateway maps the requests to the microservices.
```java
public class ApiGateway {

View File

@ -29,7 +29,7 @@
<parent>
<artifactId>api-gateway</artifactId>
<groupId>com.iluwatar</groupId>
<version>1.24.0-SNAPSHOT</version>
<version>1.23.0-SNAPSHOT</version>
</parent>
<modelVersion>4.0.0</modelVersion>
<artifactId>api-gateway-service</artifactId>

View File

@ -23,16 +23,11 @@
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 org.slf4j.Logger;
import org.springframework.stereotype.Component;
/**
@ -40,8 +35,6 @@ import org.springframework.stereotype.Component;
*/
@Component
public class ImageClientImpl implements ImageClient {
private static final Logger LOGGER = getLogger(ImageClientImpl.class);
/**
* Makes a simple HTTP Get request to the Image microservice.
*
@ -56,26 +49,12 @@ public class ImageClientImpl implements ImageClient {
.build();
try {
LOGGER.info("Sending request to fetch image path");
var httpResponse = httpClient.send(httpGet, BodyHandlers.ofString());
logResponse(httpResponse);
return httpResponse.body();
} catch (IOException | InterruptedException e) {
LOGGER.error("Failure occurred while getting image path", e);
e.printStackTrace();
}
return null;
}
private void logResponse(HttpResponse<String> httpResponse) {
if (isSuccessResponse(httpResponse.statusCode())) {
LOGGER.info("Image path received successfully");
} else {
LOGGER.warn("Image path request failed");
}
}
private boolean isSuccessResponse(int responseCode) {
return responseCode >= 200 && responseCode <= 299;
}
}

View File

@ -23,26 +23,18 @@
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 org.slf4j.Logger;
import org.springframework.stereotype.Component;
/**
* An adapter to communicate with the Price microservice.
*/
@Component
public class PriceClientImpl implements PriceClient {
private static final Logger LOGGER = getLogger(PriceClientImpl.class);
/**
* Makes a simple HTTP Get request to the Price microservice.
*
@ -57,26 +49,12 @@ public class PriceClientImpl implements PriceClient {
.build();
try {
LOGGER.info("Sending request to fetch price info");
var httpResponse = httpClient.send(httpGet, BodyHandlers.ofString());
logResponse(httpResponse);
return httpResponse.body();
} catch (IOException | InterruptedException e) {
LOGGER.error("Failure occurred while getting price info", e);
e.printStackTrace();
}
return null;
}
private void logResponse(HttpResponse<String> httpResponse) {
if (isSuccessResponse(httpResponse.statusCode())) {
LOGGER.info("Price info received successfully");
} else {
LOGGER.warn("Price info request failed");
}
}
private boolean isSuccessResponse(int responseCode) {
return responseCode >= 200 && responseCode <= 299;
}
}

View File

@ -29,7 +29,7 @@
<parent>
<artifactId>api-gateway</artifactId>
<groupId>com.iluwatar</groupId>
<version>1.24.0-SNAPSHOT</version>
<version>1.23.0-SNAPSHOT</version>
</parent>
<modelVersion>4.0.0</modelVersion>
<artifactId>image-microservice</artifactId>

View File

@ -23,20 +23,15 @@
package com.iluwatar.image.microservice;
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.
*/
@RestController
public class ImageController {
private static final Logger LOGGER = getLogger(ImageController.class);
/**
* An endpoint for a user to retrieve an image path.
@ -45,7 +40,6 @@ public class ImageController {
*/
@RequestMapping(value = "/image-path", method = RequestMethod.GET)
public String getImagePath() {
LOGGER.info("Successfully found image path");
return "/product-image.png";
}
}

View File

@ -29,7 +29,7 @@
<parent>
<artifactId>java-design-patterns</artifactId>
<groupId>com.iluwatar</groupId>
<version>1.24.0-SNAPSHOT</version>
<version>1.23.0-SNAPSHOT</version>
</parent>
<modelVersion>4.0.0</modelVersion>
<artifactId>api-gateway</artifactId>

View File

@ -29,7 +29,7 @@
<parent>
<artifactId>api-gateway</artifactId>
<groupId>com.iluwatar</groupId>
<version>1.24.0-SNAPSHOT</version>
<version>1.23.0-SNAPSHOT</version>
</parent>
<modelVersion>4.0.0</modelVersion>

View File

@ -23,20 +23,15 @@
package com.iluwatar.price.microservice;
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.
*/
@RestController
public class PriceController {
private static final Logger LOGGER = getLogger(PriceController.class);
/**
* An endpoint for a user to retrieve a product's price.
@ -45,7 +40,6 @@ public class PriceController {
*/
@RequestMapping(value = "/price", method = RequestMethod.GET)
public String getPrice() {
LOGGER.info("Successfully found price info");
return "20";
}
}

View File

@ -9,137 +9,22 @@ tags:
---
## Also known as
Given/When/Then
## Intent
Arrange/Act/Assert (AAA) is a pattern for organizing unit tests.
The Arrange/Act/Assert (AAA) is a pattern for organizing unit tests.
It breaks tests down into three clear and distinct steps:
1. Arrange: Perform the setup and initialization required for the test.
2. Act: Take action(s) required for the test.
3. Assert: Verify the outcome(s) of the test.
## Explanation
This pattern has several significant benefits. It creates a clear separation between a test's
setup, operations, and results. This structure makes the code easier to read and understand. If
you place the steps in order and format your code to separate them, you can scan a test and
quickly comprehend what it does.
It also enforces a certain degree of discipline when you write your tests. You have to think
clearly about the three steps your test will perform. It makes tests more natural to write at
the same time since you already have an outline.
Real world example
> We need to write comprehensive and clear unit test suite for a class.
In plain words
> Arrange/Act/Assert is a testing pattern that organizes tests into three clear steps for easy
> maintenance.
WikiWikiWeb says
> Arrange/Act/Assert is a pattern for arranging and formatting code in UnitTest methods.
**Programmatic Example**
Let's first introduce our `Cash` class to be unit tested.
```java
public class Cash {
private int amount;
Cash(int amount) {
this.amount = amount;
}
void plus(int addend) {
amount += addend;
}
boolean minus(int subtrahend) {
if (amount >= subtrahend) {
amount -= subtrahend;
return true;
} else {
return false;
}
}
int count() {
return amount;
}
}
```
Then we write our unit tests according to Arrange/Act/Assert pattern. Notice the clearly
separated steps for each unit test.
```java
public class CashAAATest {
@Test
public void testPlus() {
//Arrange
var cash = new Cash(3);
//Act
cash.plus(4);
//Assert
assertEquals(7, cash.count());
}
@Test
public void testMinus() {
//Arrange
var cash = new Cash(8);
//Act
var result = cash.minus(5);
//Assert
assertTrue(result);
assertEquals(3, cash.count());
}
@Test
public void testInsufficientMinus() {
//Arrange
var cash = new Cash(1);
//Act
var result = cash.minus(6);
//Assert
assertFalse(result);
assertEquals(1, cash.count());
}
@Test
public void testUpdate() {
//Arrange
var cash = new Cash(5);
//Act
cash.plus(6);
var result = cash.minus(3);
//Assert
assertTrue(result);
assertEquals(8, cash.count());
}
}
```
## Applicability
Use Arrange/Act/Assert pattern when
* You need to structure your unit tests so that they're easier to read, maintain, and enhance.
* you need to structure your unit tests so they're easier to read, maintain, and enhance.
## Credits
* [Arrange, Act, Assert: What is AAA Testing?](https://blog.ncrunch.net/post/arrange-act-assert-aaa-testing.aspx)
* [Bill Wake: 3A Arrange, Act, Assert](https://xp123.com/articles/3a-arrange-act-assert/)
* [Martin Fowler: GivenWhenThen](https://martinfowler.com/bliki/GivenWhenThen.html)
* [xUnit Test Patterns: Refactoring Test Code](https://www.amazon.com/gp/product/0131495054/ref=as_li_qf_asin_il_tl?ie=UTF8&tag=javadesignpat-20&creative=9325&linkCode=as2&creativeASIN=0131495054&linkId=99701e8f4af2f7e8dd50d720c9b63dbf)
* [Unit Testing Principles, Practices, and Patterns](https://www.amazon.com/gp/product/1617296279/ref=as_li_qf_asin_il_tl?ie=UTF8&tag=javadesignpat-20&creative=9325&linkCode=as2&creativeASIN=1617296279&linkId=74c75cf22a63c3e4758ae08aa0a0cc35)
* [Test Driven Development: By Example](https://www.amazon.com/gp/product/0321146530/ref=as_li_qf_asin_il_tl?ie=UTF8&tag=javadesignpat-20&creative=9325&linkCode=as2&creativeASIN=0321146530&linkId=5c63a93d8c1175b84ca5087472ef0e05)

View File

@ -29,7 +29,7 @@
<parent>
<artifactId>java-design-patterns</artifactId>
<groupId>com.iluwatar</groupId>
<version>1.24.0-SNAPSHOT</version>
<version>1.23.0-SNAPSHOT</version>
</parent>
<modelVersion>4.0.0</modelVersion>

View File

@ -60,7 +60,7 @@ public class CashAAATest {
//Act
cash.plus(4);
//Assert
assertEquals(7, cash.count());
assertEquals(cash.count(), 7);
}
@Test
@ -71,7 +71,7 @@ public class CashAAATest {
var result = cash.minus(5);
//Assert
assertTrue(result);
assertEquals(3, cash.count());
assertEquals(cash.count(), 3);
}
@Test
@ -82,7 +82,7 @@ public class CashAAATest {
var result = cash.minus(6);
//Assert
assertFalse(result);
assertEquals(1, cash.count());
assertEquals(cash.count(), 1);
}
@Test
@ -94,6 +94,6 @@ public class CashAAATest {
var result = cash.minus(3);
//Assert
assertTrue(result);
assertEquals(8, cash.count());
assertEquals(cash.count(), 8);
}
}

View File

@ -44,16 +44,16 @@ public class CashAntiAAATest {
var cash = new Cash(3);
//test plus
cash.plus(4);
assertEquals(7, cash.count());
assertEquals(cash.count(), 7);
//test minus
cash = new Cash(8);
assertTrue(cash.minus(5));
assertEquals(3, cash.count());
assertEquals(cash.count(), 3);
assertFalse(cash.minus(6));
assertEquals(3, cash.count());
assertEquals(cash.count(), 3);
//test update
cash.plus(5);
assertTrue(cash.minus(5));
assertEquals(3, cash.count());
assertEquals(cash.count(), 3);
}
}

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@ -22,7 +22,7 @@
<parent>
<groupId>com.iluwatar</groupId>
<artifactId>java-design-patterns</artifactId>
<version>1.24.0-SNAPSHOT</version>
<version>1.23.0-SNAPSHOT</version>
</parent>
<artifactId>async-method-invocation</artifactId>
<dependencies>

View File

@ -100,7 +100,7 @@ public class ThreadAsyncExecutor implements AsyncExecutor {
void setValue(T value) {
this.value = value;
this.state = COMPLETED;
this.callback.ifPresent(ac -> ac.onComplete(value, Optional.empty()));
this.callback.ifPresent(ac -> ac.onComplete(value, Optional.<Exception>empty()));
synchronized (lock) {
lock.notifyAll();
}

View File

@ -25,24 +25,12 @@ package com.iluwatar.async.method.invocation;
import org.junit.jupiter.api.Test;
import static org.junit.jupiter.api.Assertions.assertDoesNotThrow;
/**
* Application test
*/
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[]{}));
void test() throws Exception {
App.main(new String[]{});
}
}

View File

@ -20,7 +20,7 @@
<parent>
<artifactId>java-design-patterns</artifactId>
<groupId>com.iluwatar</groupId>
<version>1.24.0-SNAPSHOT</version>
<version>1.23.0-SNAPSHOT</version>
</parent>
<modelVersion>4.0.0</modelVersion>

View File

@ -24,26 +24,15 @@
package com.iluwatar.balking;
import org.junit.jupiter.api.Test;
import org.junit.jupiter.api.function.Executable;
import static org.junit.jupiter.api.Assertions.assertDoesNotThrow;
/**
* Application test
*/
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((Executable) App::main);
void main() {
App.main();
}
}

View File

@ -9,26 +9,20 @@ tags:
---
## Also known as
Handle/Body
## Intent
Decouple an abstraction from its implementation so that the two can vary independently.
## Explanation
Real world example
> Consider you have a weapon with different enchantments, and you are supposed to allow mixing
> different weapons with different enchantments. What would you do? Create multiple copies of each
> of the weapons for each of the enchantments or would you just create separate enchantment and set
> it for the weapon as needed? Bridge pattern allows you to do the second.
> Consider you have a weapon with different enchantments and you are supposed to allow mixing different weapons with different enchantments. What would you do? Create multiple copies of each of the weapons for each of the enchantments or would you just create separate enchantment and set it for the weapon as needed? Bridge pattern allows you to do the second.
In Plain Words
> Bridge pattern is about preferring composition over inheritance. Implementation details are pushed
> from a hierarchy to another object with a separate hierarchy.
> Bridge pattern is about preferring composition over inheritance. Implementation details are pushed from a hierarchy to another object with a separate hierarchy.
Wikipedia says
@ -36,7 +30,7 @@ Wikipedia says
**Programmatic Example**
Translating our weapon example from above. Here we have the `Weapon` hierarchy:
Translating our weapon example from above. Here we have the `Weapon` hierarchy
```java
public interface Weapon {
@ -111,7 +105,7 @@ public class Hammer implements Weapon {
}
```
Here's the separate enchantment hierarchy:
And the separate enchantment hierarchy
```java
public interface Enchantment {
@ -157,7 +151,7 @@ public class SoulEatingEnchantment implements Enchantment {
}
```
Here are both hierarchies in action:
And both the hierarchies in action
```java
var enchantedSword = new Sword(new SoulEatingEnchantment());
@ -184,21 +178,18 @@ hammer.unwield();
```
## Class diagram
![alt text](./etc/bridge.urm.png "Bridge class diagram")
## Applicability
Use the Bridge pattern when
* You want to avoid a permanent binding between an abstraction and its implementation. This might be the case, for example, when the implementation must be selected or switched at run-time.
* Both the abstractions and their implementations should be extensible by subclassing. In this case, the Bridge pattern lets you combine the different abstractions and implementations and extend them independently.
* Changes in the implementation of an abstraction should have no impact on clients; that is, their code should not have to be recompiled.
* You have a proliferation of classes. Such a class hierarchy indicates the need for splitting an object into two parts. Rumbaugh uses the term "nested generalizations" to refer to such class hierarchies.
* You want to share an implementation among multiple objects (perhaps using reference counting), and this fact should be hidden from the client. A simple example is Coplien's String class, in which multiple objects can share the same string representation.
* you want to avoid a permanent binding between an abstraction and its implementation. This might be the case, for example, when the implementation must be selected or switched at run-time.
* both the abstractions and their implementations should be extensible by subclassing. In this case, the Bridge pattern lets you combine the different abstractions and implementations and extend them independently
* changes in the implementation of an abstraction should have no impact on clients; that is, their code should not have to be recompiled.
* you have a proliferation of classes. Such a class hierarchy indicates the need for splitting an object into two parts. Rumbaugh uses the term "nested generalizations" to refer to such class hierarchies
* you want to share an implementation among multiple objects (perhaps using reference counting), and this fact should be hidden from the client. A simple example is Coplien's String class, in which multiple objects can share the same string representation.
## Tutorial
* [Bridge Pattern Tutorial](https://www.journaldev.com/1491/bridge-design-pattern-java)
## Credits

View File

@ -22,7 +22,7 @@
<parent>
<groupId>com.iluwatar</groupId>
<artifactId>java-design-patterns</artifactId>
<version>1.24.0-SNAPSHOT</version>
<version>1.23.0-SNAPSHOT</version>
</parent>
<artifactId>bridge</artifactId>
<dependencies>

View File

@ -25,22 +25,12 @@ package com.iluwatar.bridge;
import org.junit.jupiter.api.Test;
import static org.junit.jupiter.api.Assertions.assertDoesNotThrow;
/**
* Application test
*/
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[]{}));
void test() {
App.main(new String[]{});
}
}

View File

@ -9,47 +9,36 @@ tags:
---
## Intent
Separate the construction of a complex object from its representation so that the same construction
process can create different representations.
Separate the construction of a complex object from its
representation so that the same construction process can create different
representations.
## Explanation
Real world example
> Imagine a character generator for a role-playing game. The easiest option is to let the computer
> create the character for you. If you want to manually select the character details like
> profession, gender, hair color etc. the character generation becomes a step-by-step process that
> completes when all the selections are ready.
> Imagine a character generator for a role playing game. The easiest option is to let computer create the character for you. But if you want to select the character details like profession, gender, hair color etc. the character generation becomes a step-by-step process that completes when all the selections are ready.
In plain words
> Allows you to create different flavors of an object while avoiding constructor pollution. Useful
> when there could be several flavors of an object. Or when there are a lot of steps involved in
> creation of an object.
> Allows you to create different flavors of an object while avoiding constructor pollution. Useful when there could be several flavors of an object. Or when there are a lot of steps involved in creation of an object.
Wikipedia says
> The builder pattern is an object creation software design pattern with the intentions of finding
> a solution to the telescoping constructor anti-pattern.
> The builder pattern is an object creation software design pattern with the intentions of finding a solution to the telescoping constructor anti-pattern.
Having said that let me add a bit about what telescoping constructor anti-pattern is. At one point
or the other, we have all seen a constructor like below:
Having said that let me add a bit about what telescoping constructor anti-pattern is. At one point or the other we have all seen a constructor like below:
```java
public Hero(Profession profession, String name, HairType hairType, HairColor hairColor, Armor armor, Weapon weapon) {
}
```
As you can see the number of constructor parameters can quickly get out of hand, and it may become
difficult to understand the arrangement of parameters. Plus this parameter list could keep on
growing if you would want to add more options in the future. This is called telescoping constructor
anti-pattern.
As you can see the number of constructor parameters can quickly get out of hand and it might become difficult to understand the arrangement of parameters. Plus this parameter list could keep on growing if you would want to add more options in future. This is called telescoping constructor anti-pattern.
**Programmatic Example**
The sane alternative is to use the Builder pattern. First of all we have our hero that we want to
create:
The sane alternative is to use the Builder pattern. First of all we have our hero that we want to create
```java
public final class Hero {
@ -71,7 +60,7 @@ public final class Hero {
}
```
Then we have the builder:
And then we have the builder
```java
public static class Builder {
@ -116,22 +105,20 @@ Then we have the builder:
}
```
Then it can be used as:
And then it can be used as:
```java
var mage = new Hero.Builder(Profession.MAGE, "Riobard").withHairColor(HairColor.BLACK).withWeapon(Weapon.DAGGER).build();
```
## Class diagram
![alt text](./etc/builder.urm.png "Builder class diagram")
## Applicability
Use the Builder pattern when
* The algorithm for creating a complex object should be independent of the parts that make up the object and how they're assembled
* The construction process must allow different representations for the object that's constructed
* the algorithm for creating a complex object should be independent of the parts that make up the object and how they're assembled
* the construction process must allow different representations for the object that's constructed
## Real world examples

View File

@ -22,7 +22,7 @@
<parent>
<groupId>com.iluwatar</groupId>
<artifactId>java-design-patterns</artifactId>
<version>1.24.0-SNAPSHOT</version>
<version>1.23.0-SNAPSHOT</version>
</parent>
<artifactId>builder</artifactId>
<dependencies>

View File

@ -25,23 +25,12 @@ package com.iluwatar.builder;
import org.junit.jupiter.api.Test;
import static org.junit.jupiter.api.Assertions.assertDoesNotThrow;
/**
* Application test
*/
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[]{}));
void test() {
App.main(new String[]{});
}
}

View File

@ -22,7 +22,7 @@
<parent>
<groupId>com.iluwatar</groupId>
<artifactId>java-design-patterns</artifactId>
<version>1.24.0-SNAPSHOT</version>
<version>1.23.0-SNAPSHOT</version>
</parent>
<artifactId>business-delegate</artifactId>
<dependencies>

View File

@ -28,7 +28,7 @@ package com.iluwatar.business.delegate;
*/
public class Client {
private final BusinessDelegate businessDelegate;
private BusinessDelegate businessDelegate;
public Client(BusinessDelegate businessDelegate) {
this.businessDelegate = businessDelegate;

View File

@ -28,5 +28,5 @@ package com.iluwatar.business.delegate;
*/
public enum ServiceType {
EJB, JMS
EJB, JMS;
}

View File

@ -21,13 +21,6 @@
* THE SOFTWARE.
*/
package com.iluwatar.filterer;
import org.junit.jupiter.api.Test;
class AppTest {
@Test
void shouldLaunchApp() {
App.main(new String[]{});
}
module com.iluwatar.business.delegate {
requires org.slf4j;
}

View File

@ -27,23 +27,13 @@ import org.junit.jupiter.api.Test;
import java.io.IOException;
import static org.junit.jupiter.api.Assertions.assertDoesNotThrow;
/**
* Tests that Business Delegate 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.
*/
public class AppTest {
@Test
void shouldExecuteApplicationWithoutException() {
assertDoesNotThrow(() -> App.main(new String[]{}));
public void test() throws IOException {
String[] args = {};
App.main(args);
}
}

View File

@ -20,7 +20,7 @@
<parent>
<artifactId>java-design-patterns</artifactId>
<groupId>com.iluwatar</groupId>
<version>1.24.0-SNAPSHOT</version>
<version>1.23.0-SNAPSHOT</version>
</parent>
<modelVersion>4.0.0</modelVersion>

View File

@ -58,14 +58,12 @@ public class App {
var vm = new VirtualMachine();
vm.getWizards()[0] = wizard;
String literal = "LITERAL 0";
interpretInstruction(literal, vm);
interpretInstruction(literal, vm);
interpretInstruction("LITERAL 0", vm);
interpretInstruction("LITERAL 0", vm);
interpretInstruction("GET_HEALTH", vm);
interpretInstruction(literal, vm);
interpretInstruction("LITERAL 0", vm);
interpretInstruction("GET_AGILITY", vm);
interpretInstruction(literal, vm);
interpretInstruction("LITERAL 0", vm);
interpretInstruction("GET_WISDOM ", vm);
interpretInstruction("ADD", vm);
interpretInstruction("LITERAL 2", vm);

View File

@ -30,9 +30,9 @@ import java.util.Stack;
*/
public class VirtualMachine {
private final Stack<Integer> stack = new Stack<>();
private Stack<Integer> stack = new Stack<>();
private final Wizard[] wizards = new Wizard[2];
private Wizard[] wizards = new Wizard[2];
/**
* Constructor.

View File

@ -25,22 +25,13 @@ package com.iluwatar.bytecode;
import org.junit.jupiter.api.Test;
import static org.junit.jupiter.api.Assertions.assertDoesNotThrow;
/**
* Application test
*/
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.
*/
public class AppTest {
@Test
void shouldExecuteApplicationWithoutException() {
assertDoesNotThrow(() -> App.main(new String[]{}));
public void test() {
App.main(new String[]{});
}
}

View File

@ -104,7 +104,7 @@ public class VirtualMachineTest {
bytecode[2] = LITERAL.getIntValue();
bytecode[3] = 50; // health amount
bytecode[4] = SET_HEALTH.getIntValue();
bytecode[5] = LITERAL.getIntValue();
bytecode[5] = LITERAL.getIntValue();;
bytecode[6] = wizardNumber;
bytecode[7] = GET_HEALTH.getIntValue();

View File

@ -29,7 +29,7 @@
<parent>
<groupId>com.iluwatar</groupId>
<artifactId>java-design-patterns</artifactId>
<version>1.24.0-SNAPSHOT</version>
<version>1.23.0-SNAPSHOT</version>
</parent>
<artifactId>caching</artifactId>
<dependencies>

View File

@ -29,7 +29,7 @@ package com.iluwatar.caching;
public enum CachingPolicy {
THROUGH("through"), AROUND("around"), BEHIND("behind"), ASIDE("aside");
private final String policy;
private String policy;
CachingPolicy(String policy) {
this.policy = policy;

View File

@ -27,23 +27,12 @@ import org.junit.jupiter.api.Test;
import java.io.IOException;
import static org.junit.jupiter.api.Assertions.assertDoesNotThrow;
/**
* Tests that Caching 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.
*/
public class AppTest {
@Test
void shouldExecuteApplicationWithoutException() {
assertDoesNotThrow(() -> App.main(new String[]{}));
public void test() {
App.main(new String[]{});
}
}

View File

@ -9,16 +9,14 @@ tags:
---
## Intent
Callback is a piece of executable code that is passed as an argument to other code, which is
expected to call back (execute) the argument at some convenient time.
Callback is a piece of executable code that is passed as an argument to other code, which is expected to call back
(execute) the argument at some convenient time.
## Explanation
Real world example
> We need to be notified after executing task has finished. We pass a callback method for
> the executor and wait for it to call back on us.
> We need to be notified after executing task has finished. We pass a callback method for the executor and wait for it to call back on us.
In plain words
@ -26,9 +24,7 @@ In plain words
Wikipedia says
> In computer programming, a callback, also known as a "call-after" function, is any executable
> code that is passed as an argument to other code; that other code is expected to call
> back (execute) the argument at a given time.
> In computer programming, a callback, also known as a "call-after" function, is any executable code that is passed as an argument to other code; that other code is expected to call back (execute) the argument at a given time.
**Programmatic Example**
@ -65,7 +61,7 @@ public final class SimpleTask extends Task {
}
```
Finally, here's how we execute a task and receive a callback when it's finished.
Finally here's how we execute a task and receive a callback when it's finished.
```java
var task = new SimpleTask();
@ -73,15 +69,13 @@ Finally, here's how we execute a task and receive a callback when it's finished.
```
## Class diagram
![alt text](./etc/callback.png "Callback")
## Applicability
Use the Callback pattern when
* when some arbitrary synchronous or asynchronous action must be performed after execution of some defined activity.
## Real world examples
* [CyclicBarrier](http://docs.oracle.com/javase/7/docs/api/java/util/concurrent/CyclicBarrier.html#CyclicBarrier%28int,%20java.lang.Runnable%29) constructor can accept a callback that will be triggered every time a barrier is tripped.
* [CyclicBarrier](http://docs.oracle.com/javase/7/docs/api/java/util/concurrent/CyclicBarrier.html#CyclicBarrier%28int,%20java.lang.Runnable%29) constructor can accept callback that will be triggered every time when barrier is tripped.

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@ -8,6 +8,11 @@ package com.iluwatar.callback {
interface Callback {
+ call() {abstract}
}
class LambdasApp {
- LOGGER : Logger {static}
- LambdasApp()
+ main(args : String[]) {static}
}
class SimpleTask {
- LOGGER : Logger {static}
+ SimpleTask()

View File

@ -29,7 +29,7 @@
<parent>
<groupId>com.iluwatar</groupId>
<artifactId>java-design-patterns</artifactId>
<version>1.24.0-SNAPSHOT</version>
<version>1.23.0-SNAPSHOT</version>
</parent>
<artifactId>callback</artifactId>
<dependencies>

View File

@ -0,0 +1,26 @@
/*
* The MIT License
* Copyright © 2014-2019 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.
*/
module com.iluwatar.callback {
requires org.slf4j;
}

View File

@ -25,23 +25,12 @@ package com.iluwatar.callback;
import org.junit.jupiter.api.Test;
import static org.junit.jupiter.api.Assertions.assertDoesNotThrow;
/**
* Tests that Callback 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.
*/
public class AppTest {
@Test
void shouldExecuteApplicationWithoutException() {
assertDoesNotThrow(() -> App.main(new String[]{}));
public void test() {
App.main(new String[]{});
}
}

View File

@ -9,32 +9,27 @@ tags:
---
## Intent
Avoid coupling the sender of a request to its receiver by giving more than one object a chance to
handle the request. Chain the receiving objects and pass the request along the chain until an object
handles it.
Avoid coupling the sender of a request to its receiver by giving
more than one object a chance to handle the request. Chain the receiving
objects and pass the request along the chain until an object handles it.
## Explanation
Real world example
> The Orc King gives loud orders to his army. The closest one to react is the commander, then
> officer and then soldier. The commander, officer and soldier here form a chain of responsibility.
> The Orc King gives loud orders to his army. The closest one to react is the commander, then officer and then soldier. The commander, officer and soldier here form a chain of responsibility.
In plain words
> It helps to build a chain of objects. A request enters from one end and keeps going from an object
> to another until it finds a suitable handler.
> It helps building a chain of objects. Request enters from one end and keeps going from object to object till it finds the suitable handler.
Wikipedia says
> In object-oriented design, the chain-of-responsibility pattern is a design pattern consisting of
> a source of command objects and a series of processing objects. Each processing object contains
> logic that defines the types of command objects that it can handle; the rest are passed to the
> next processing object in the chain.
> In object-oriented design, the chain-of-responsibility pattern is a design pattern consisting of a source of command objects and a series of processing objects. Each processing object contains logic that defines the types of command objects that it can handle; the rest are passed to the next processing object in the chain.
**Programmatic Example**
Translating our example with the orcs from above. First we have the `Request` class:
Translating our example with orcs from above. First we have the request class
```java
public class Request {
@ -70,7 +65,7 @@ Then the request handler hierarchy
```java
public abstract class RequestHandler {
private static final Logger LOGGER = LoggerFactory.getLogger(RequestHandler.class);
private final RequestHandler next;
private RequestHandler next;
public RequestHandler(RequestHandler next) {
this.next = next;
@ -145,16 +140,14 @@ king.makeRequest(new Request(RequestType.COLLECT_TAX, "collect tax")); // Orc so
```
## Class diagram
![alt text](./etc/chain.urm.png "Chain of Responsibility class diagram")
## Applicability
Use Chain of Responsibility when
* More than one object may handle a request, and the handler isn't known a priori. The handler should be ascertained automatically.
* You want to issue a request to one of several objects without specifying the receiver explicitly.
* The set of objects that can handle a request should be specified dynamically.
* more than one object may handle a request, and the handler isn't known a priori. The handler should be ascertained automatically
* you want to issue a request to one of several objects without specifying the receiver explicitly
* the set of objects that can handle a request should be specified dynamically
## Real world examples

View File

@ -29,7 +29,7 @@
<parent>
<groupId>com.iluwatar</groupId>
<artifactId>java-design-patterns</artifactId>
<version>1.24.0-SNAPSHOT</version>
<version>1.23.0-SNAPSHOT</version>
</parent>
<artifactId>chain</artifactId>
<dependencies>

View File

@ -33,7 +33,7 @@ public abstract class RequestHandler {
private static final Logger LOGGER = LoggerFactory.getLogger(RequestHandler.class);
private final RequestHandler next;
private RequestHandler next;
public RequestHandler(RequestHandler next) {
this.next = next;

View File

@ -0,0 +1,26 @@
/*
* The MIT License
* Copyright © 2014-2019 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.
*/
module com.iluwatar.chain {
requires org.slf4j;
}

View File

@ -25,23 +25,13 @@ package com.iluwatar.chain;
import org.junit.jupiter.api.Test;
import static org.junit.jupiter.api.Assertions.assertDoesNotThrow;
/**
* Application test
*/
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.
*/
public class AppTest {
@Test
void shouldExecuteApplicationWithoutException() {
assertDoesNotThrow(() -> App.main(new String[]{}));
public void test() {
App.main(new String[]{});
}
}

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