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35 Commits

Author SHA1 Message Date
dafc57d622 Fix typo 2021-06-22 20:45:17 +03:00
d327918b13 Grammar fixes for visitor 2021-06-22 20:35:33 +03:00
5b0f4a9697 Grammar fixes, template method 2021-06-22 20:30:39 +03:00
808df54dc0 Grammar fixes for strategy 2021-06-22 20:24:25 +03:00
b014dc2f00 Grammar fixes to state pattern 2021-06-22 20:15:34 +03:00
9a2c5aa9aa Update singleton 2021-06-22 20:10:26 +03:00
ebcc857664 Proxy pattern grammar fixes 2021-06-22 19:59:43 +03:00
11efae38f2 Update explanation for the prototype pattern 2021-06-22 19:53:58 +03:00
bbc2a9ddb1 Grammar fixes for observer 2021-06-22 17:05:41 +03:00
2b7cc410b0 Grammatical fixes to memento 2021-06-22 08:03:51 +03:00
a403c84add Add explanation for mediator pattern 2021-06-21 21:33:41 +03:00
86362e12f6 Update iterator readme 2021-06-20 22:06:42 +03:00
1f6833986e Interpreter explanation 2021-06-14 20:00:35 +03:00
3b1f82a2a4 Update flyweight 2021-06-13 18:57:21 +03:00
6feca5bd01 Update factory method 2021-06-13 18:35:13 +03:00
588b106ada Update factory example 2021-06-13 10:50:29 +03:00
0d41af972d Update facade 2021-06-13 10:08:35 +03:00
57783aa341 Minor updates to decorator pattern 2021-06-13 09:58:41 +03:00
abc8e0d88a Fixes to headings 2021-06-13 09:49:02 +03:00
26c06d8f7f Improvements to the composite example 2021-06-13 09:39:35 +03:00
ed98e7a128 Update chain of responsibility 2021-06-12 20:16:42 +03:00
0f9f3b90c2 Fixes to builder pattern grammar 2021-06-12 18:49:40 +03:00
e361223def Update bridge pattern readme 2021-06-12 18:40:31 +03:00
7a46174391 Grammatical fixes to command pattern 2021-06-09 08:05:24 +03:00
bbdff14a66 Fix: Fixing License issue in MVVM pattern (#1701)
* Fixing License issue in MVVM pattern

* Updating LICENSE.md

* Updating pom.xml

* License header update to MVVM module only.

* Updating pom and removing gpl txt

* Adding gpl txt file

Co-authored-by: Jinisha <Jinisha@LAPTOP-VG38PNMC.fios-router.home>
2021-06-08 21:40:24 +03:00
eade10a98d docs: add samuelpsouza as a contributor (#1785)
* docs: update README.md [skip ci]

* docs: update .all-contributorsrc [skip ci]

Co-authored-by: Subhrodip Mohanta <hello@subho.xyz>
Co-authored-by: allcontributors[bot] <46447321+allcontributors[bot]@users.noreply.github.com>
2021-06-07 22:32:23 +05:30
43e7ca515a refactor: #1012 - Resolve Sonar report: missing assertions in several AppTest classes (#1784)
Co-authored-by: Subhrodip Mohanta <hello@subho.xyz>
2021-06-07 22:30:44 +05:30
f6d43975fa docs: Grammatical fixes for Abstract Factory (#1782)
* Grammatical fixes

* Update abstract-factory/README.md

Co-authored-by: Subhrodip Mohanta <hello@subho.xyz>
2021-06-05 13:03:25 +05:30
c0d36894c2 docs: add Xenilo137 as a contributor (#1781)
* docs: update README.md [skip ci]

* docs: update .all-contributorsrc [skip ci]

Co-authored-by: allcontributors[bot] <46447321+allcontributors[bot]@users.noreply.github.com>
2021-06-04 21:54:17 +03:00
6cf025447a fix: change 'swinged' to 'swung' in sword.java and hammer.java of bridge pattern (#1779)
* minor (non-coding) change

* Update Sword.java
2021-06-04 21:50:40 +03:00
dafe02f1be docs: add JuanManuelAbate as a contributor (#1780)
* docs: update README.md [skip ci]

* docs: update .all-contributorsrc [skip ci]

Co-authored-by: allcontributors[bot] <46447321+allcontributors[bot]@users.noreply.github.com>
2021-06-04 21:39:47 +03:00
784cdee819 localizations: #1771 Spanish translation and languages codes (#1777)
* #1771 Move translations to a new directory to have more organization

* #1771 spanish translation

* #1771 change the language codes to follow ISO 639-1 and change the links

* #1771 remove country flags
2021-06-04 21:36:42 +03:00
5e434b783e fix: added license headers to newly created files (#1775) 2021-05-31 22:39:42 +03:00
f597fc1b07 fix: Fixed pages showing up in wrong language (#1752)
* Fix languages

* Missed change for version number

* Add language field for presentation

* Revert change in README for double buffer

Co-authored-by: Jackie Nim <=>
2021-05-19 19:49:05 +03:00
1b880c1818 docs: add tao-sun2 as a contributor (#1757)
* docs: update README.md [skip ci]

* docs: update .all-contributorsrc [skip ci]

Co-authored-by: allcontributors[bot] <46447321+allcontributors[bot]@users.noreply.github.com>
2021-05-17 22:09:29 +03:00
321 changed files with 3492 additions and 484 deletions

View File

@ -1514,6 +1514,42 @@
"contributions": [
"code"
]
},
{
"login": "tao-sun2",
"name": "Tao",
"avatar_url": "https://avatars.githubusercontent.com/u/66189688?v=4",
"profile": "https://github.com/tao-sun2",
"contributions": [
"code"
]
},
{
"login": "JuanManuelAbate",
"name": "Juan Manuel Abate",
"avatar_url": "https://avatars.githubusercontent.com/u/16357060?v=4",
"profile": "https://github.com/JuanManuelAbate",
"contributions": [
"translation"
]
},
{
"login": "Xenilo137",
"name": "Xenilo137",
"avatar_url": "https://avatars.githubusercontent.com/u/24865069?v=4",
"profile": "https://github.com/Xenilo137",
"contributions": [
"code"
]
},
{
"login": "samuelpsouza",
"name": "Samuel Souza",
"avatar_url": "https://avatars.githubusercontent.com/u/17254162?v=4",
"profile": "https://www.linkedin.com/in/souzasamuel/",
"contributions": [
"code"
]
}
],
"contributorsPerLine": 4,

View File

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

View File

@ -6,16 +6,16 @@
![Java CI](https://github.com/iluwatar/java-design-patterns/workflows/Java%20CI/badge.svg)
[![License MIT](https://img.shields.io/badge/license-MIT-blue.svg)](https://raw.githubusercontent.com/iluwatar/java-design-patterns/master/LICENSE.md)
[![Lines of Code](https://sonarcloud.io/api/project_badges/measure?project=iluwatar_java-design-patterns&metric=ncloc)](https://sonarcloud.io/dashboard?id=iluwatar_java-design-patterns)
[![Lines of Code](https://sonarcloud.io/api/project_badges/measure?project=iluwatar_java-design-patterns&metric=ncloc)](https://sonarcloud.io/dashboard?id=iluwatar_java-design-patterns)
[![Coverage](https://sonarcloud.io/api/project_badges/measure?project=iluwatar_java-design-patterns&metric=coverage)](https://sonarcloud.io/dashboard?id=iluwatar_java-design-patterns)
[![Join the chat at https://gitter.im/iluwatar/java-design-patterns](https://badges.gitter.im/Join%20Chat.svg)](https://gitter.im/iluwatar/java-design-patterns?utm_source=badge&utm_medium=badge&utm_campaign=pr-badge&utm_content=badge)
<!-- ALL-CONTRIBUTORS-BADGE:START - Do not remove or modify this section -->
[![All Contributors](https://img.shields.io/badge/all_contributors-166-orange.svg?style=flat-square)](#contributors-)
[![All Contributors](https://img.shields.io/badge/all_contributors-170-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), [![AR](/assets/flags/AR.png)**AR**](/ar/README.md)
Read in different language : [**zh**](/localization/zh/README.md), [**ko**](/localization/ko/README.md), [**fr**](/localization/fr/README.md), [**tr**](/localization/tr/README.md), [**ar**](/localization/ar/README.md), [**es**](/localization/es/README.md)
<br/>
@ -34,7 +34,7 @@ are familiar with the patterns.
# Getting started
This site showcases Java Design Patterns. The solutions have been developed by
experienced programmers and architects from the open source community. The
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
@ -49,7 +49,7 @@ patterns should only be introduced when they are needed for practical
extensibility.
Once you are familiar with these concepts you can start drilling down into the
[available design patterns](https://java-design-patterns.com/patterns/) by any
[available design patterns](https://java-design-patterns.com/patterns/) by any
of the following approaches
- Search for a specific pattern by name. Can't find one? Please report a new pattern [here](https://github.com/iluwatar/java-design-patterns/issues).
@ -61,8 +61,8 @@ in your architectures and have as much fun learning them as we had developing th
# How to contribute
If you are willing to contribute to the project you will find the relevant information in
our [developer wiki](https://github.com/iluwatar/java-design-patterns/wiki). We will help
If you are willing to contribute to the project you will find the relevant information in
our [developer wiki](https://github.com/iluwatar/java-design-patterns/wiki). We will help
you and answer your questions in the [Gitter chatroom](https://gitter.im/iluwatar/java-design-patterns).
# License
@ -324,6 +324,12 @@ This project is licensed under the terms of the MIT license.
<tr>
<td align="center"><a href="https://github.com/JackieNim"><img src="https://avatars.githubusercontent.com/u/4138836?v=4?s=100" width="100px;" alt=""/><br /><sub><b>JackieNim</b></sub></a><br /><a href="https://github.com/iluwatar/java-design-patterns/commits?author=JackieNim" title="Code">💻</a></td>
<td align="center"><a href="https://github.com/EdisonE3"><img src="https://avatars.githubusercontent.com/u/52118917?v=4?s=100" width="100px;" alt=""/><br /><sub><b>EdisonE3</b></sub></a><br /><a href="https://github.com/iluwatar/java-design-patterns/commits?author=EdisonE3" title="Code">💻</a></td>
<td align="center"><a href="https://github.com/tao-sun2"><img src="https://avatars.githubusercontent.com/u/66189688?v=4?s=100" width="100px;" alt=""/><br /><sub><b>Tao</b></sub></a><br /><a href="https://github.com/iluwatar/java-design-patterns/commits?author=tao-sun2" title="Code">💻</a></td>
<td align="center"><a href="https://github.com/JuanManuelAbate"><img src="https://avatars.githubusercontent.com/u/16357060?v=4?s=100" width="100px;" alt=""/><br /><sub><b>Juan Manuel Abate</b></sub></a><br /><a href="#translation-JuanManuelAbate" title="Translation">🌍</a></td>
</tr>
<tr>
<td align="center"><a href="https://github.com/Xenilo137"><img src="https://avatars.githubusercontent.com/u/24865069?v=4?s=100" width="100px;" alt=""/><br /><sub><b>Xenilo137</b></sub></a><br /><a href="https://github.com/iluwatar/java-design-patterns/commits?author=Xenilo137" title="Code">💻</a></td>
<td align="center"><a href="https://www.linkedin.com/in/souzasamuel/"><img src="https://avatars.githubusercontent.com/u/17254162?v=4?s=100" width="100px;" alt=""/><br /><sub><b>Samuel Souza</b></sub></a><br /><a href="https://github.com/iluwatar/java-design-patterns/commits?author=samuelpsouza" title="Code">💻</a></td>
</tr>
</table>

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

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@ -4,6 +4,7 @@ title: Abstract Factory
folder: abstract-factory
permalink: /patterns/abstract-factory/
categories: Creational
language: en
tags:
- Gang of Four
---
@ -19,9 +20,9 @@ objects without specifying their concrete classes.
## Explanation
Real world example
Real-world example
> To create a kingdom we need objects with a common theme. 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 a common theme. The elven kingdom needs an elven king, elven castle, and elven army whereas the orcish kingdom needs an orcish king, orcish castle, and orcish army. There is a dependency between the objects in the kingdom.
In plain words
@ -33,7 +34,7 @@ Wikipedia says
**Programmatic Example**
Translating the kingdom example above. First of all we have some interfaces and implementation for the objects in the
Translating the kingdom example above. First of all, we have some interfaces and implementation for the objects in the
kingdom.
```java
@ -51,21 +52,21 @@ public interface Army {
// Elven implementations ->
public class ElfCastle implements Castle {
static final String DESCRIPTION = "This is the Elven castle!";
static final String DESCRIPTION = "This is the elven castle!";
@Override
public String getDescription() {
return DESCRIPTION;
}
}
public class ElfKing implements King {
static final String DESCRIPTION = "This is the Elven king!";
static final String DESCRIPTION = "This is the elven king!";
@Override
public String getDescription() {
return DESCRIPTION;
}
}
public class ElfArmy implements Army {
static final String DESCRIPTION = "This is the Elven Army!";
static final String DESCRIPTION = "This is the elven Army!";
@Override
public String getDescription() {
return DESCRIPTION;
@ -76,7 +77,7 @@ public class ElfArmy implements Army {
```
Then we have the abstraction and implementations for the kingdom factory
Then we have the abstraction and implementations for the kingdom factory.
```java
public interface KingdomFactory {
@ -110,7 +111,7 @@ public class OrcKingdomFactory implements KingdomFactory {
}
```
Now we have our abstract factory that lets us make family of related objects i.e. Elven kingdom factory creates Elven castle, king and army etc.
Now we have the abstract factory that lets us make a family of related objects i.e. elven kingdom factory creates elven castle, king and army, etc.
```java
var factory = new ElfKingdomFactory();
@ -126,13 +127,13 @@ army.getDescription();
Program output:
```java
This is the Elven castle!
This is the Elven king!
This is the Elven Army!
This is the elven castle!
This is the elven king!
This is the elven Army!
```
Now, we can design a factory for our different kingdom factories. In this example, we created FactoryMaker, responsible for returning an instance of either ElfKingdomFactory or OrcKingdomFactory.
The client can use FactoryMaker to create the desired concrete factory which, in turn, will produce different concrete objects (Army, King, Castle).
Now, we can design a factory for our different kingdom factories. In this example, we created `FactoryMaker`, responsible for returning an instance of either `ElfKingdomFactory` or `OrcKingdomFactory`.
The client can use `FactoryMaker` to create the desired concrete factory which, in turn, will produce different concrete objects (derived from `Army`, `King`, `Castle`).
In this example, we also used an enum to parameterize which type of kingdom factory the client will ask for.
```java
@ -178,8 +179,8 @@ public static void main(String[] args) {
Use the Abstract Factory pattern when
* The system should be independent of how its products are created, composed and represented
* The system should be configured with one of multiple families of products
* The system should be independent of how its products are created, composed, and represented
* The system should be configured with one of the 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.
@ -195,13 +196,13 @@ Example use cases
* Unit test case writing becomes much easier
* UI tools for different OS
## Consequences:
## Consequences
* Dependency injection in java hides the service class dependencies that can lead to runtime errors that would have been caught at compile time.
* While the pattern is great when creating predefined objects, adding the new ones might be challenging.
* The code becomes more complicated than it should be, since a lot of new interfaces and classes are introduced along with the pattern.
* The code becomes more complicated than it should be since a lot of new interfaces and classes are introduced along with the pattern.
## Tutorial
## Tutorials
* [Abstract Factory Pattern Tutorial](https://www.journaldev.com/1418/abstract-factory-design-pattern-in-java)

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

View File

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

View File

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

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

View File

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

View File

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

View File

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

View File

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

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@ -28,10 +28,7 @@ import org.junit.jupiter.api.Test;
import static org.junit.jupiter.api.Assertions.assertDoesNotThrow;
/**
* 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.
* Check whether the execution of the main method in {@link App} throws an exception.
*/
class AppTest {

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@ -4,6 +4,7 @@ title: Active Object
folder: active-object
permalink: /patterns/active-object/
categories: Concurrency
language: en
tags:
- Performance
---

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

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@ -4,6 +4,7 @@ title: Adapter
folder: adapter
permalink: /patterns/adapter/
categories: Structural
language: en
tags:
- Gang of Four
---
@ -104,7 +105,7 @@ Use the Adapter pattern when
* you need to use several existing subclasses, but it's impractical to adapt their interface by subclassing every one. An object adapter can adapt the interface of its parent class.
* most of the applications using third party libraries use adapters as a middle layer between the application and the 3rd party library to decouple the application from the library. If another library has to be used only an adapter for the new library is required without having to change the application code.
## Consequences:
## Consequences
Class and object adapters have different trade-offs. A class adapter
* adapts Adaptee to Target by committing to a concrete Adaptee class. As a consequence, a class adapter wont work when we want to adapt a class and all its subclasses.
@ -117,7 +118,7 @@ An object adapter
* makes it harder to override Adaptee behavior. It will require subclassing Adaptee and making Adapter refer to the subclass rather than the Adaptee itself.
## Real world examples
## Known uses
* [java.util.Arrays#asList()](http://docs.oracle.com/javase/8/docs/api/java/util/Arrays.html#asList%28T...%29)
* [java.util.Collections#list()](https://docs.oracle.com/javase/8/docs/api/java/util/Collections.html#list-java.util.Enumeration-)

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

View File

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

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

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

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

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

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

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

View File

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

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@ -4,6 +4,7 @@ title: Builder
folder: builder
permalink: /patterns/builder/
categories: Creational
language: en
tags:
- Gang of Four
---
@ -15,11 +16,11 @@ process can create different representations.
## Explanation
Real world example
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
> 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
@ -48,7 +49,7 @@ anti-pattern.
**Programmatic Example**
The sane alternative is to use the Builder pattern. First of all we have our hero that we want to
The sane alternative is to use the Builder pattern. First of all, we have our hero that we want to
create:
```java
@ -133,7 +134,7 @@ Use the Builder pattern when
* The algorithm for creating a complex object should be independent of the parts that make up the object and how they're assembled
* The construction process must allow different representations for the object that's constructed
## Real world examples
## Known uses
* [java.lang.StringBuilder](http://docs.oracle.com/javase/8/docs/api/java/lang/StringBuilder.html)
* [java.nio.ByteBuffer](http://docs.oracle.com/javase/8/docs/api/java/nio/ByteBuffer.html#put-byte-) as well as similar buffers such as FloatBuffer, IntBuffer and so on.

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

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@ -4,6 +4,7 @@ title: Bytecode
folder: bytecode
permalink: /patterns/bytecode/
categories: Behavioral
language: en
tags:
- Game programming
---

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@ -4,6 +4,7 @@ title: Caching
folder: caching
permalink: /patterns/caching/
categories: Behavioral
language: en
tags:
- Performance
- Cloud distributed

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@ -4,6 +4,7 @@ title: Callback
folder: callback
permalink: /patterns/callback/
categories: Idiom
language: en
tags:
- Reactive
---

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@ -1,24 +1,26 @@
---
layout: pattern
title: Chain of responsibility
folder: chain
permalink: /patterns/chain/
folder: chain-of-responsibility
permalink: /patterns/chain-of-responsibility/
categories: Behavioral
language: en
tags:
- Gang of Four
---
## 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.
## Explanation
Real world example
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.
> an officer, and then a soldier. The commander, officer, and soldier form a chain of responsibility.
In plain words
@ -34,7 +36,7 @@ Wikipedia says
**Programmatic Example**
Translating our example with the orcs from above. First we have the `Request` class:
Translating our example with the orcs from above. First, we have the `Request` class:
```java
public class Request {
@ -65,7 +67,7 @@ public enum RequestType {
}
```
Then the request handler hierarchy
Next, we show the request handler hierarchy.
```java
@Slf4j
@ -115,7 +117,7 @@ public class OrcCommander extends RequestHandler {
```
Then we have the Orc King who gives the orders and forms the chain
The Orc King gives the orders and forms the chain.
```java
public class OrcKing {
@ -135,18 +137,26 @@ public class OrcKing {
}
```
Then it is used as follows
The chain of responsibility in action.
```java
var king = new OrcKing();
king.makeRequest(new Request(RequestType.DEFEND_CASTLE, "defend castle")); // Orc commander handling request "defend castle"
king.makeRequest(new Request(RequestType.TORTURE_PRISONER, "torture prisoner")); // Orc officer handling request "torture prisoner"
king.makeRequest(new Request(RequestType.COLLECT_TAX, "collect tax")); // Orc soldier handling request "collect tax"
king.makeRequest(new Request(RequestType.DEFEND_CASTLE, "defend castle"));
king.makeRequest(new Request(RequestType.TORTURE_PRISONER, "torture prisoner"));
king.makeRequest(new Request(RequestType.COLLECT_TAX, "collect tax"));
```
The console output.
```
Orc commander handling request "defend castle"
Orc officer handling request "torture prisoner"
Orc soldier handling request "collect tax"
```
## Class diagram
![alt text](./etc/chain.urm.png "Chain of Responsibility class diagram")
![alt text](./etc/chain-of-responsibility.urm.png "Chain of Responsibility class diagram")
## Applicability
@ -156,7 +166,7 @@ Use Chain of Responsibility when
* 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
## Known uses
* [java.util.logging.Logger#log()](http://docs.oracle.com/javase/8/docs/api/java/util/logging/Logger.html#log%28java.util.logging.Level,%20java.lang.String%29)
* [Apache Commons Chain](https://commons.apache.org/proper/commons-chain/index.html)

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After

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@ -31,7 +31,7 @@
<artifactId>java-design-patterns</artifactId>
<version>1.25.0-SNAPSHOT</version>
</parent>
<artifactId>chain</artifactId>
<artifactId>chain-of-responsibility</artifactId>
<dependencies>
<dependency>
<groupId>org.junit.jupiter</groupId>

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@ -4,6 +4,7 @@ title: Circuit Breaker
folder: circuit-breaker
permalink: /patterns/circuit-breaker/
categories: Behavioral
language: en
tags:
- Performance
- Decoupling

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@ -4,6 +4,7 @@ title: Static Content Hosting
folder: cloud-static-content-hosting
permalink: /patterns/cloud-static-content-hosting/
categories: Cloud
language: en
tags:
- Cloud distributed
---

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@ -4,6 +4,7 @@ title: Collection Pipeline
folder: collection-pipeline
permalink: /patterns/collection-pipeline/
categories: Functional
language: en
tags:
- Reactive
---

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@ -4,6 +4,7 @@ title: Combinator
folder: combinator
permalink: /patterns/combinator/
categories: Idiom
language: en
tags:
- Reactive
---

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@ -1,9 +1,10 @@
---
---
layout: pattern
title: Command
folder: command
permalink: /patterns/command/
categories: Behavioral
language: en
tags:
- Gang of Four
---
@ -18,7 +19,7 @@ Encapsulate a request as an object, thereby letting you parameterize clients wit
requests, queue or log requests, and support undoable operations.
## Explanation
Real world example
Real-world example
> There is a wizard casting spells on a goblin. The spells are executed on the goblin one by one.
> The first spell shrinks the goblin and the second makes him invisible. Then the wizard reverses
@ -134,7 +135,7 @@ public class Goblin extends Target {
}
```
Finally we have the wizard in main function who casts spell
Finally, we have the wizard in the main function casting spells.
```java
public static void main(String[] args) {
@ -201,32 +202,29 @@ Use the Command pattern when you want to:
* Parameterize objects by an action to perform. You can express such parameterization in a
procedural language with a callback function, that is, a function that's registered somewhere to be
called at a later point. Commands are an object-oriented replacement for callbacks.
* Specify, queue, and execute requests at different times. A Command object can have a lifetime
* Specify, queue, and execute requests at different times. A Command object can have a life
independent of the original request. If the receiver of a request can be represented in an address
space-independent way, then you can transfer a command object for the request to a different process
and fulfill the request there.
* Support undo. The Command's execute operation can store state for reversing its effects in the
command itself. The Command interface must have an added un-execute operation that reverses the
effects of a previous call to execute. The executed commands are stored in a history list.
Unlimited-level undo and redo is achieved by traversing this list backwards and forwards calling
un-execute and execute, respectively.
Unlimited-level undo and redo functionality is achieved by traversing this list backward and forward
calling un-execute and execute, respectively.
* Support logging changes so that they can be reapplied in case of a system crash. By augmenting the
Command interface with load and store operations, you can keep a persistent log of changes.
Recovering from a crash involves reloading logged commands from disk and re-executing them with
Recovering from a crash involves reloading logged commands from the disk and re-executing them with
the execute operation.
* Structure a system around high-level operations build on primitive operations. Such a structure is
common in information systems that support transactions. A transaction encapsulates a set of changes
to data. The Command pattern offers a way to model transactions. Commands have a common interface,
common in information systems that support transactions. A transaction encapsulates a set of data
changes. The Command pattern offers a way to model transactions. Commands have a common interface,
letting you invoke all transactions the same way. The pattern also makes it easy to extend the
system with new transactions.
* Keep a history of requests.
* Implement callback functionality.
* Implement the undo functionality.
## Typical Use Case
* To keep a history of requests
* Implement callback functionality
* Implement the undo functionality
## Real world examples
## Known uses
* [java.lang.Runnable](http://docs.oracle.com/javase/8/docs/api/java/lang/Runnable.html)
* [org.junit.runners.model.Statement](https://github.com/junit-team/junit4/blob/master/src/main/java/org/junit/runners/model/Statement.java)

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@ -26,7 +26,7 @@ package com.iluwatar.command;
/**
* The Command pattern is a behavioral design pattern in which an object is used to encapsulate all
* information needed to perform an action or trigger an event at a later time. This information
* includes the method name, the object that owns the method and values for the method parameters.
* includes the method name, the object that owns the method, and values for the method parameters.
*
* <p>Four terms always associated with the command pattern are command, receiver, invoker and
* client. A command object (spell) knows about the receiver (target) and invokes a method of the

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@ -4,6 +4,7 @@ title: Commander
folder: commander
permalink: /patterns/commander/
categories: Concurrency
language: en
tags:
- Cloud distributed
---

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@ -4,6 +4,7 @@ title: Composite Entity
folder: composite-entity
permalink: /patterns/composite-entity/
categories: Structural
language: en
tags:
- Enterprise Integration Pattern
---

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@ -1,4 +1,28 @@
<?xml version="1.0" encoding="UTF-8"?>
<!--
The MIT License
Copyright © 2014-2021 Ilkka Seppälä
Permission is hereby granted, free of charge, to any person obtaining a copy
of this software and associated documentation files (the "Software"), to deal
in the Software without restriction, including without limitation the rights
to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
copies of the Software, and to permit persons to whom the Software is
furnished to do so, subject to the following conditions:
The above copyright notice and this permission notice shall be included in
all copies or substantial portions of the Software.
THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
THE SOFTWARE.
-->
<project xmlns="http://maven.apache.org/POM/4.0.0"
xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">

View File

@ -1,3 +1,26 @@
/*
* The MIT License
* Copyright © 2014-2021 Ilkka Seppälä
*
* Permission is hereby granted, free of charge, to any person obtaining a copy
* of this software and associated documentation files (the "Software"), to deal
* in the Software without restriction, including without limitation the rights
* to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
* copies of the Software, and to permit persons to whom the Software is
* furnished to do so, subject to the following conditions:
*
* The above copyright notice and this permission notice shall be included in
* all copies or substantial portions of the Software.
*
* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
* IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
* FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
* AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
* LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
* OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
* THE SOFTWARE.
*/
package com.iluwatar.compositeentity;
import java.util.Arrays;

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@ -1,3 +1,26 @@
/*
* The MIT License
* Copyright © 2014-2021 Ilkka Seppälä
*
* Permission is hereby granted, free of charge, to any person obtaining a copy
* of this software and associated documentation files (the "Software"), to deal
* in the Software without restriction, including without limitation the rights
* to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
* copies of the Software, and to permit persons to whom the Software is
* furnished to do so, subject to the following conditions:
*
* The above copyright notice and this permission notice shall be included in
* all copies or substantial portions of the Software.
*
* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
* IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
* FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
* AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
* LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
* OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
* THE SOFTWARE.
*/
package com.iluwatar.compositeentity;
import java.util.Arrays;

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@ -1,3 +1,26 @@
/*
* The MIT License
* Copyright © 2014-2021 Ilkka Seppälä
*
* Permission is hereby granted, free of charge, to any person obtaining a copy
* of this software and associated documentation files (the "Software"), to deal
* in the Software without restriction, including without limitation the rights
* to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
* copies of the Software, and to permit persons to whom the Software is
* furnished to do so, subject to the following conditions:
*
* The above copyright notice and this permission notice shall be included in
* all copies or substantial portions of the Software.
*
* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
* IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
* FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
* AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
* LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
* OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
* THE SOFTWARE.
*/
package com.iluwatar.compositeentity;
/**

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@ -1,3 +1,26 @@
/*
* The MIT License
* Copyright © 2014-2021 Ilkka Seppälä
*
* Permission is hereby granted, free of charge, to any person obtaining a copy
* of this software and associated documentation files (the "Software"), to deal
* in the Software without restriction, including without limitation the rights
* to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
* copies of the Software, and to permit persons to whom the Software is
* furnished to do so, subject to the following conditions:
*
* The above copyright notice and this permission notice shall be included in
* all copies or substantial portions of the Software.
*
* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
* IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
* FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
* AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
* LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
* OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
* THE SOFTWARE.
*/
package com.iluwatar.compositeentity;
/**

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@ -1,3 +1,26 @@
/*
* The MIT License
* Copyright © 2014-2021 Ilkka Seppälä
*
* Permission is hereby granted, free of charge, to any person obtaining a copy
* of this software and associated documentation files (the "Software"), to deal
* in the Software without restriction, including without limitation the rights
* to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
* copies of the Software, and to permit persons to whom the Software is
* furnished to do so, subject to the following conditions:
*
* The above copyright notice and this permission notice shall be included in
* all copies or substantial portions of the Software.
*
* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
* IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
* FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
* AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
* LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
* OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
* THE SOFTWARE.
*/
package com.iluwatar.compositeentity;
/**

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@ -1,3 +1,26 @@
/*
* The MIT License
* Copyright © 2014-2021 Ilkka Seppälä
*
* Permission is hereby granted, free of charge, to any person obtaining a copy
* of this software and associated documentation files (the "Software"), to deal
* in the Software without restriction, including without limitation the rights
* to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
* copies of the Software, and to permit persons to whom the Software is
* furnished to do so, subject to the following conditions:
*
* The above copyright notice and this permission notice shall be included in
* all copies or substantial portions of the Software.
*
* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
* IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
* FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
* AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
* LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
* OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
* THE SOFTWARE.
*/
package com.iluwatar.compositeentity;
/**

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@ -1,3 +1,26 @@
/*
* The MIT License
* Copyright © 2014-2021 Ilkka Seppälä
*
* Permission is hereby granted, free of charge, to any person obtaining a copy
* of this software and associated documentation files (the "Software"), to deal
* in the Software without restriction, including without limitation the rights
* to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
* copies of the Software, and to permit persons to whom the Software is
* furnished to do so, subject to the following conditions:
*
* The above copyright notice and this permission notice shall be included in
* all copies or substantial portions of the Software.
*
* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
* IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
* FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
* AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
* LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
* OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
* THE SOFTWARE.
*/
package com.iluwatar.compositeentity;
/**

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@ -1,3 +1,26 @@
/*
* The MIT License
* Copyright © 2014-2021 Ilkka Seppälä
*
* Permission is hereby granted, free of charge, to any person obtaining a copy
* of this software and associated documentation files (the "Software"), to deal
* in the Software without restriction, including without limitation the rights
* to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
* copies of the Software, and to permit persons to whom the Software is
* furnished to do so, subject to the following conditions:
*
* The above copyright notice and this permission notice shall be included in
* all copies or substantial portions of the Software.
*
* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
* IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
* FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
* AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
* LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
* OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
* THE SOFTWARE.
*/
package com.iluwatar.compositeentity;
import static org.junit.jupiter.api.Assertions.assertDoesNotThrow;

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@ -1,3 +1,26 @@
/*
* The MIT License
* Copyright © 2014-2021 Ilkka Seppälä
*
* Permission is hereby granted, free of charge, to any person obtaining a copy
* of this software and associated documentation files (the "Software"), to deal
* in the Software without restriction, including without limitation the rights
* to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
* copies of the Software, and to permit persons to whom the Software is
* furnished to do so, subject to the following conditions:
*
* The above copyright notice and this permission notice shall be included in
* all copies or substantial portions of the Software.
*
* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
* IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
* FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
* AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
* LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
* OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
* THE SOFTWARE.
*/
package com.iluwatar.compositeentity;
import org.junit.jupiter.api.Test;

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@ -4,6 +4,7 @@ title: Composite
folder: composite
permalink: /patterns/composite/
categories: Structural
language: en
tags:
- Gang of Four
---
@ -15,15 +16,15 @@ treat individual objects and compositions of objects uniformly.
## Explanation
Real world example
Real-world example
> Every sentence is composed of words which are in turn composed of characters. Each of these
> objects is printable and they can have something printed before or after them like sentence always
> ends with full stop and word always has space before it.
> objects are printable and they can have something printed before or after them like sentence
> always ends with full stop and word always has space before it.
In plain words
> Composite pattern lets clients treat the individual objects in a uniform manner.
> Composite pattern lets clients uniformly treat the individual objects.
Wikipedia says
@ -153,10 +154,22 @@ public class Messenger {
And then it can be used as:
```java
var orcMessage = new Messenger().messageFromOrcs();
orcMessage.print(); // Where there is a whip there is a way.
var elfMessage = new Messenger().messageFromElves();
elfMessage.print(); // Much wind pours from your mouth.
var messenger = new Messenger();
LOGGER.info("Message from the orcs: ");
messenger.messageFromOrcs().print();
LOGGER.info("Message from the elves: ");
messenger.messageFromElves().print();
```
The console output:
```
Message from the orcs:
Where there is a whip there is a way.
Message from the elves:
Much wind pours from your mouth.
```
## Class diagram
@ -171,7 +184,7 @@ Use the Composite pattern when
* You want clients to be able to ignore the difference between compositions of objects and
individual objects. Clients will treat all objects in the composite structure uniformly.
## Real world examples
## Known uses
* [java.awt.Container](http://docs.oracle.com/javase/8/docs/api/java/awt/Container.html) and [java.awt.Component](http://docs.oracle.com/javase/8/docs/api/java/awt/Component.html)
* [Apache Wicket](https://github.com/apache/wicket) component tree, see [Component](https://github.com/apache/wicket/blob/91e154702ab1ff3481ef6cbb04c6044814b7e130/wicket-core/src/main/java/org/apache/wicket/Component.java) and [MarkupContainer](https://github.com/apache/wicket/blob/b60ec64d0b50a611a9549809c9ab216f0ffa3ae3/wicket-core/src/main/java/org/apache/wicket/MarkupContainer.java)

View File

@ -45,14 +45,13 @@ public class App {
* @param args command line args
*/
public static void main(String[] args) {
var messenger = new Messenger();
LOGGER.info("Message from the orcs: ");
messenger.messageFromOrcs().print();
var orcMessage = new Messenger().messageFromOrcs();
orcMessage.print();
LOGGER.info("\nMessage from the elves: ");
var elfMessage = new Messenger().messageFromElves();
elfMessage.print();
LOGGER.info("Message from the elves: ");
messenger.messageFromElves().print();
}
}

View File

@ -39,6 +39,6 @@ public class Sentence extends LetterComposite {
@Override
protected void printThisAfter() {
System.out.print(".");
System.out.print(".\n");
}
}

View File

@ -4,6 +4,7 @@ title: Converter
folder: converter
permalink: /patterns/converter/
categories: Creational
language: en
tags:
- Decoupling
---

View File

@ -4,6 +4,7 @@ title: CQRS
folder: cqrs
permalink: /patterns/cqrs/
categories: Architectural
language: en
tags:
- Performance
- Cloud distributed

View File

@ -4,6 +4,7 @@ title: Data Access Object
folder: dao
permalink: /patterns/dao/
categories: Architectural
language: en
tags:
- Data access
---

View File

@ -5,6 +5,7 @@ folder: data-bus
permalink: /patterns/data-bus/
categories: Architectural
language: en
tags:
- Decoupling
---

View File

@ -4,6 +4,7 @@ title: Data Locality
folder: data-locality
permalink: /patterns/data-locality/
categories: Behavioral
language: en
tags:
- Game programming
- Performance

View File

@ -4,6 +4,7 @@ title: Data Mapper
folder: data-mapper
permalink: /patterns/data-mapper/
categories: Architectural
language: en
tags:
- Decoupling
---

View File

@ -4,6 +4,7 @@ title: Data Transfer Object
folder: data-transfer-object
permalink: /patterns/data-transfer-object/
categories: Architectural
language: en
tags:
- Performance
---

View File

@ -4,8 +4,9 @@ title: Decorator
folder: decorator
permalink: /patterns/decorator/
categories: Structural
language: en
tags:
- Gang Of Four
- Gang of Four
- Extensibility
---
@ -20,9 +21,9 @@ alternative to subclassing for extending functionality.
## Explanation
Real world example
Real-world example
> There is an angry troll living in the nearby hills. Usually it goes bare handed but sometimes it
> There is an angry troll living in the nearby hills. Usually, it goes bare-handed but sometimes it
> has a weapon. To arm the troll it's not necessary to create a new troll but to decorate it
> dynamically with a suitable weapon.
@ -71,7 +72,7 @@ public class SimpleTroll implements Troll {
}
```
Next we want to add club for the troll. We can do it dynamically by using a decorator:
Next, we want to add a club for the troll. We can do it dynamically by using a decorator:
```java
@Slf4j
@ -105,23 +106,33 @@ Here's the troll in action:
```java
// simple troll
LOGGER.info("A simple looking troll approaches.");
var troll = new SimpleTroll();
troll.attack(); // The troll tries to grab you!
troll.fleeBattle(); // The troll shrieks in horror and runs away!
troll.attack();
troll.fleeBattle();
LOGGER.info("Simple troll power: {}.\n", troll.getAttackPower());
// change the behavior of the simple troll by adding a decorator
LOGGER.info("A troll with huge club surprises you.");
var clubbedTroll = new ClubbedTroll(troll);
clubbedTroll.attack(); // The troll tries to grab you! The troll swings at you with a club!
clubbedTroll.fleeBattle(); // The troll shrieks in horror and runs away!
clubbedTroll.attack();
clubbedTroll.fleeBattle();
LOGGER.info("Clubbed troll power: {}.\n", clubbedTroll.getAttackPower());
```
Program output:
```java
A simple looking troll approaches.
The troll tries to grab you!
The troll shrieks in horror and runs away!
The troll tries to grab you! The troll swings at you with a club!
Simple troll power: 10.
A troll with huge club surprises you.
The troll tries to grab you!
The troll swings at you with a club!
The troll shrieks in horror and runs away!
Clubbed troll power: 20.
```
## Class diagram
@ -139,11 +150,11 @@ affecting other objects.
are possible and would produce an explosion of subclasses to support every combination. Or a class
definition may be hidden or otherwise unavailable for subclassing.
## Tutorial
## Tutorials
* [Decorator Pattern Tutorial](https://www.journaldev.com/1540/decorator-design-pattern-in-java-example)
## Real world examples
## Known uses
* [java.io.InputStream](http://docs.oracle.com/javase/8/docs/api/java/io/InputStream.html), [java.io.OutputStream](http://docs.oracle.com/javase/8/docs/api/java/io/OutputStream.html),
[java.io.Reader](http://docs.oracle.com/javase/8/docs/api/java/io/Reader.html) and [java.io.Writer](http://docs.oracle.com/javase/8/docs/api/java/io/Writer.html)

View File

@ -50,13 +50,13 @@ public class App {
var troll = new SimpleTroll();
troll.attack();
troll.fleeBattle();
LOGGER.info("Simple troll power {}.\n", troll.getAttackPower());
LOGGER.info("Simple troll power: {}.\n", troll.getAttackPower());
// change the behavior of the simple troll by adding a decorator
LOGGER.info("A troll with huge club surprises you.");
var clubbedTroll = new ClubbedTroll(troll);
clubbedTroll.attack();
clubbedTroll.fleeBattle();
LOGGER.info("Clubbed troll power {}.\n", clubbedTroll.getAttackPower());
LOGGER.info("Clubbed troll power: {}.\n", clubbedTroll.getAttackPower());
}
}

View File

@ -4,6 +4,7 @@ title: Delegation
folder: delegation
permalink: /patterns/delegation/
categories: Structural
language: en
tags:
- Decoupling
---

View File

@ -4,6 +4,7 @@ title: Dependency Injection
folder: dependency-injection
permalink: /patterns/dependency-injection/
categories: Creational
language: en
tags:
- Decoupling
---

View File

@ -4,6 +4,7 @@ title: Dirty Flag
folder: dirty-flag
permalink: /patterns/dirty-flag/
categories: Behavioral
language: en
tags:
- Game programming
- Performance

View File

@ -4,6 +4,7 @@ title: Double Buffer
folder: double-buffer
permalink: /patterns/double-buffer/
categories: Behavioral
language: en
tags:
- Performance
- Game programming

View File

@ -4,6 +4,7 @@ title: Double Checked Locking
folder: double-checked-locking
permalink: /patterns/double-checked-locking/
categories: Idiom
language: en
tags:
- Performance
---

View File

@ -4,6 +4,7 @@ title: Double Dispatch
folder: double-dispatch
permalink: /patterns/double-dispatch/
categories: Idiom
language: en
tags:
- Extensibility
---

View File

@ -4,6 +4,7 @@ title: EIP Aggregator
folder: eip-aggregator
permalink: /patterns/eip-aggregator/
categories: Integration
language: en
tags:
- Enterprise Integration Pattern
---

View File

@ -4,6 +4,7 @@ title: EIP Message Channel
folder: eip-message-channel
permalink: /patterns/eip-message-channel/
categories: Integration
language: en
tags:
- Enterprise Integration Pattern
---

View File

@ -4,6 +4,7 @@ title: EIP Publish Subscribe
folder: eip-publish-subscribe
permalink: /patterns/eip-publish-subscribe/
categories: Integration
language: en
tags:
- Enterprise Integration Pattern
---

View File

@ -4,6 +4,7 @@ title: EIP Splitter
folder: eip-splitter
permalink: /patterns/eip-splitter/
categories: Integration
language: en
tags:
- Enterprise Integration Pattern
---

View File

@ -4,6 +4,7 @@ title: EIP Wire Tap
folder: eip-wire-tap
permalink: /patterns/eip-wire-tap/
categories: Integration
language: en
tags:
- Enterprise Integration Pattern
---

View File

@ -4,6 +4,7 @@ title: Event Aggregator
folder: event-aggregator
permalink: /patterns/event-aggregator/
categories: Structural
language: en
tags:
- Reactive
---

View File

@ -4,6 +4,7 @@ title: Event-based Asynchronous
folder: event-asynchronous
permalink: /patterns/event-asynchronous/
categories: Concurrency
language: en
tags:
- Reactive
---

View File

@ -4,6 +4,7 @@ title: Event Driven Architecture
folder: event-driven-architecture
permalink: /patterns/event-driven-architecture/
categories: Architectural
language: en
tags:
- Reactive
---

View File

@ -4,6 +4,7 @@ title: Event Queue
folder: event-queue
permalink: /patterns/event-queue/
categories: Concurrency
language: en
tags:
- Game programming
---

View File

@ -4,6 +4,7 @@ title: Event Sourcing
folder: event-sourcing
permalink: /patterns/event-sourcing/
categories: Architectural
language: en
tags:
- Performance
- Cloud distributed

View File

@ -4,6 +4,7 @@ title: Execute Around
folder: execute-around
permalink: /patterns/execute-around/
categories: Idiom
language: en
tags:
- Extensibility
---

View File

@ -4,6 +4,7 @@ title: Extension objects
folder: extension-objects
permalink: /patterns/extension-objects/
categories: Behavioral
language: en
tags:
- Extensibility
---

View File

@ -4,6 +4,7 @@ title: Facade
folder: facade
permalink: /patterns/facade/
categories: Structural
language: en
tags:
- Gang Of Four
- Decoupling
@ -16,7 +17,7 @@ interface that makes the subsystem easier to use.
## Explanation
Real world example
Real-world example
> How does a goldmine work? "Well, the miners go down there and dig gold!" you say. That is what you
> believe because you are using a simple interface that goldmine provides on the outside, internally

View File

@ -4,6 +4,7 @@ title: Factory Kit
folder: factory-kit
permalink: /patterns/factory-kit/
categories: Creational
language: en
tags:
- Extensibility
---

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