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383 changed files with 627 additions and 12881 deletions

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@ -1460,141 +1460,6 @@
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"code"
]
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"name": "余林颖",
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"profile": "https://al-assad.github.io/notion/",
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"name": "Alain",
"avatar_url": "https://avatars.githubusercontent.com/u/6988911?v=4",
"profile": "https://github.com/STudio26",
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]
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"name": "VR",
"avatar_url": "https://avatars.githubusercontent.com/u/30525467?v=4",
"profile": "https://github.com/DEV-VRUPER",
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"name": "Juan Manuel Abate",
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@ -40,26 +40,26 @@ jobs:
steps:
- name: Checkout Code
uses: actions/checkout@v2
uses: actions/checkout@master
with:
# Disabling shallow clone for improving relevancy of SonarQube reporting
fetch-depth: 0
- name: Set up JDK 11
uses: actions/setup-java@v2
uses: actions/setup-java@master
with:
java-version: 11
distribution: 'adopt'
- name: Cache SonarCloud packages
uses: actions/cache@v2
uses: actions/cache@master
with:
path: ~/.sonar/cache
key: ${{ runner.os }}-sonar
restore-keys: ${{ runner.os }}-sonar
- name: Cache Maven dependencies
uses: actions/cache@v2
uses: actions/cache@master
with:
path: ~/.m2/repository
key: ${{ runner.os }}-maven-${{ hashFiles('**/pom.xml') }}

View File

@ -38,16 +38,16 @@ jobs:
steps:
- name: Checkout Code
uses: actions/checkout@v2
uses: actions/checkout@master
- name: Set up JDK 11
uses: actions/setup-java@v2
uses: actions/setup-java@master
with:
java-version: 11
distribution: 'adopt'
- name: Cache Maven Dependecies
uses: actions/cache@v2
uses: actions/cache@master
with:
path: ~/.m2/repository
key: ${{ runner.os }}-maven-${{ hashFiles('**/pom.xml') }}

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

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@ -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-175-orange.svg?style=flat-square)](#contributors-)
[![All Contributors](https://img.shields.io/badge/all_contributors-160-orange.svg?style=flat-square)](#contributors-)
<!-- ALL-CONTRIBUTORS-BADGE:END -->
<br/>
Read in different language : [**zh**](/localization/zh/README.md), [**ko**](/localization/ko/README.md), [**fr**](/localization/fr/README.md), [**tr**](/localization/tr/README.md), [**ar**](/localization/ar/README.md), [**es**](/localization/es/README.md), [**pt**](/localization/pt/README.md)
Read in different language : [![CN](/assets/flags/CN.png)**CN**](/zh/README.md), [![KR](/assets/flags/KR.png)**KR**](/ko/README.md), [![FR](/assets/flags/FR.png)**FR**](/fr/README.md), [![TR](/assets/flags/TR.png)**TR**](/tr/README.md), [![AR](/assets/flags/AR.png)**AR**](/ar/README.md)
<br/>
@ -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
@ -315,29 +315,6 @@ This project is licensed under the terms of the MIT license.
<td align="center"><a href="https://www.linkedin.com/in/jinisha-vora"><img src="https://avatars.githubusercontent.com/u/40777762?v=4?s=100" width="100px;" alt=""/><br /><sub><b>jinishavora</b></sub></a><br /><a href="https://github.com/iluwatar/java-design-patterns/pulls?q=is%3Apr+reviewed-by%3Ajinishavora" title="Reviewed Pull Requests">👀</a> <a href="https://github.com/iluwatar/java-design-patterns/commits?author=jinishavora" title="Code">💻</a></td>
<td align="center"><a href="https://github.com/eas5"><img src="https://avatars.githubusercontent.com/u/50836521?v=4?s=100" width="100px;" alt=""/><br /><sub><b>Elvys Soares</b></sub></a><br /><a href="https://github.com/iluwatar/java-design-patterns/commits?author=eas5" title="Code">💻</a></td>
</tr>
<tr>
<td align="center"><a href="https://github.com/zWeBrain"><img src="https://avatars.githubusercontent.com/u/46642512?v=4?s=100" width="100px;" alt=""/><br /><sub><b>zWeBrain</b></sub></a><br /><a href="https://github.com/iluwatar/java-design-patterns/commits?author=zWeBrain" title="Code">💻</a></td>
<td align="center"><a href="https://al-assad.github.io/notion/"><img src="https://avatars.githubusercontent.com/u/22493821?v=4?s=100" width="100px;" alt=""/><br /><sub><b>余林颖</b></sub></a><br /><a href="#translation-Al-assad" title="Translation">🌍</a></td>
<td align="center"><a href="https://github.com/STudio26"><img src="https://avatars.githubusercontent.com/u/6988911?v=4?s=100" width="100px;" alt=""/><br /><sub><b>Alain</b></sub></a><br /><a href="#translation-STudio26" title="Translation">🌍</a></td>
<td align="center"><a href="https://github.com/DEV-VRUPER"><img src="https://avatars.githubusercontent.com/u/30525467?v=4?s=100" width="100px;" alt=""/><br /><sub><b>VR</b></sub></a><br /><a href="https://github.com/iluwatar/java-design-patterns/commits?author=DEV-VRUPER" title="Documentation">📖</a></td>
</tr>
<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>
<td align="center"><a href="https://github.com/marlo2222"><img src="https://avatars.githubusercontent.com/u/40809563?v=4?s=100" width="100px;" alt=""/><br /><sub><b>Marlo Henrique</b></sub></a><br /><a href="#translation-marlo2222" title="Translation">🌍</a></td>
<td align="center"><a href="https://github.com/AndriyPyzh"><img src="https://avatars.githubusercontent.com/u/57706635?v=4?s=100" width="100px;" alt=""/><br /><sub><b>AndriyPyzh</b></sub></a><br /><a href="https://github.com/iluwatar/java-design-patterns/commits?author=AndriyPyzh" title="Code">💻</a></td>
</tr>
<tr>
<td align="center"><a href="https://github.com/karthikbhat13"><img src="https://avatars.githubusercontent.com/u/22431014?v=4?s=100" width="100px;" alt=""/><br /><sub><b>karthikbhat13</b></sub></a><br /><a href="https://github.com/iluwatar/java-design-patterns/commits?author=karthikbhat13" title="Code">💻</a></td>
<td align="center"><a href="https://github.com/mortezaadi"><img src="https://avatars.githubusercontent.com/u/1329687?v=4?s=100" width="100px;" alt=""/><br /><sub><b>Morteza Adigozalpour</b></sub></a><br /><a href="https://github.com/iluwatar/java-design-patterns/commits?author=mortezaadi" title="Code">💻</a></td>
<td align="center"><a href="https://stackoverflow.com/users/308565/nagaraj-tantri"><img src="https://avatars.githubusercontent.com/u/3784194?v=4?s=100" width="100px;" alt=""/><br /><sub><b>Nagaraj Tantri</b></sub></a><br /><a href="https://github.com/iluwatar/java-design-patterns/commits?author=tan31989" title="Code">💻</a></td>
</tr>
</table>
<!-- markdownlint-restore -->

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

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@ -4,7 +4,6 @@ title: Abstract Factory
folder: abstract-factory
permalink: /patterns/abstract-factory/
categories: Creational
language: en
tags:
- Gang of Four
---
@ -20,9 +19,9 @@ objects without specifying their concrete classes.
## Explanation
Real-world example
Real world example
> To create a kingdom we need objects with a common theme. The elven kingdom needs an elven king, elven castle, and elven army whereas the orcish kingdom needs an orcish king, orcish castle, and orcish army. There is a dependency between the objects in the kingdom.
> To create a kingdom we need objects with a common theme. Elven kingdom needs an Elven king, Elven castle and Elven army whereas Orcish kingdom needs an Orcish king, Orcish castle and Orcish army. There is a dependency between the objects in the kingdom.
In plain words
@ -34,7 +33,7 @@ Wikipedia says
**Programmatic Example**
Translating the kingdom example above. First of all, we have some interfaces and implementation for the objects in the
Translating the kingdom example above. First of all we have some interfaces and implementation for the objects in the
kingdom.
```java
@ -52,21 +51,21 @@ public interface Army {
// Elven implementations ->
public class ElfCastle implements Castle {
static final String DESCRIPTION = "This is the elven castle!";
static final String DESCRIPTION = "This is the Elven castle!";
@Override
public String getDescription() {
return DESCRIPTION;
}
}
public class ElfKing implements King {
static final String DESCRIPTION = "This is the elven king!";
static final String DESCRIPTION = "This is the Elven king!";
@Override
public String getDescription() {
return DESCRIPTION;
}
}
public class ElfArmy implements Army {
static final String DESCRIPTION = "This is the elven Army!";
static final String DESCRIPTION = "This is the Elven Army!";
@Override
public String getDescription() {
return DESCRIPTION;
@ -77,7 +76,7 @@ public class ElfArmy implements Army {
```
Then we have the abstraction and implementations for the kingdom factory.
Then we have the abstraction and implementations for the kingdom factory
```java
public interface KingdomFactory {
@ -111,7 +110,7 @@ public class OrcKingdomFactory implements KingdomFactory {
}
```
Now we have the abstract factory that lets us make a family of related objects i.e. elven kingdom factory creates elven castle, king and army, etc.
Now we have our abstract factory that lets us make family of related objects i.e. Elven kingdom factory creates Elven castle, king and army etc.
```java
var factory = new ElfKingdomFactory();
@ -127,13 +126,13 @@ army.getDescription();
Program output:
```java
This is the elven castle!
This is the elven king!
This is the elven Army!
This is the Elven castle!
This is the Elven king!
This is the Elven Army!
```
Now, we can design a factory for our different kingdom factories. In this example, we created `FactoryMaker`, responsible for returning an instance of either `ElfKingdomFactory` or `OrcKingdomFactory`.
The client can use `FactoryMaker` to create the desired concrete factory which, in turn, will produce different concrete objects (derived from `Army`, `King`, `Castle`).
Now, we can design a factory for our different kingdom factories. In this example, we created FactoryMaker, responsible for returning an instance of either ElfKingdomFactory or OrcKingdomFactory.
The client can use FactoryMaker to create the desired concrete factory which, in turn, will produce different concrete objects (Army, King, Castle).
In this example, we also used an enum to parameterize which type of kingdom factory the client will ask for.
```java
@ -179,8 +178,8 @@ public static void main(String[] args) {
Use the Abstract Factory pattern when
* The system should be independent of how its products are created, composed, and represented
* The system should be configured with one of the multiple families of products
* The system should be independent of how its products are created, composed and represented
* The system should be configured with one of multiple families of products
* The family of related product objects is designed to be used together, and you need to enforce this constraint
* You want to provide a class library of products, and you want to reveal just their interfaces, not their implementations
* The lifetime of the dependency is conceptually shorter than the lifetime of the consumer.
@ -196,13 +195,13 @@ Example use cases
* Unit test case writing becomes much easier
* UI tools for different OS
## Consequences
## Consequences:
* Dependency injection in java hides the service class dependencies that can lead to runtime errors that would have been caught at compile time.
* While the pattern is great when creating predefined objects, adding the new ones might be challenging.
* The code becomes more complicated than it should be since a lot of new interfaces and classes are introduced along with the pattern.
* The code becomes more complicated than it should be, since a lot of new interfaces and classes are introduced along with the pattern.
## Tutorials
## Tutorial
* [Abstract Factory Pattern Tutorial](https://www.journaldev.com/1418/abstract-factory-design-pattern-in-java)

View File

@ -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() {

View File

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

View File

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

View File

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

View File

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

View File

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

View File

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

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

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

View File

@ -4,7 +4,6 @@ title: Adapter
folder: adapter
permalink: /patterns/adapter/
categories: Structural
language: en
tags:
- Gang of Four
---
@ -105,7 +104,7 @@ 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.
@ -118,7 +117,7 @@ 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.
## Known uses
## Real world examples
* [java.util.Arrays#asList()](http://docs.oracle.com/javase/8/docs/api/java/util/Arrays.html#asList%28T...%29)
* [java.util.Collections#list()](https://docs.oracle.com/javase/8/docs/api/java/util/Collections.html#list-java.util.Enumeration-)

View File

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

View File

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

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

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

View File

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

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

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

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

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

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@ -4,7 +4,6 @@ title: Bridge
folder: bridge
permalink: /patterns/bridge/
categories: Structural
language: en
tags:
- Gang of Four
---
@ -19,7 +18,7 @@ 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
@ -161,36 +160,27 @@ 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();
```
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.
// 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.
```
## Class diagram

View File

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

View File

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

View File

@ -4,7 +4,6 @@ title: Builder
folder: builder
permalink: /patterns/builder/
categories: Creational
language: en
tags:
- Gang of Four
---
@ -16,11 +15,11 @@ 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
@ -49,7 +48,7 @@ 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
@ -134,7 +133,7 @@ Use the Builder pattern when
* The algorithm for creating a complex object should be independent of the parts that make up the object and how they're assembled
* The construction process must allow different representations for the object that's constructed
## Known uses
## Real world examples
* [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.

View File

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

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

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

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

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@ -1,26 +1,24 @@
---
layout: pattern
title: Chain of responsibility
folder: chain-of-responsibility
permalink: /patterns/chain-of-responsibility/
folder: chain
permalink: /patterns/chain/
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
> an officer, and then a soldier. The commander, officer, and soldier form a chain of responsibility.
> officer and then soldier. The commander, officer and soldier here form a chain of responsibility.
In plain words
@ -36,7 +34,7 @@ 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 {
@ -67,7 +65,7 @@ public enum RequestType {
}
```
Next, we show the request handler hierarchy.
Then the request handler hierarchy
```java
@Slf4j
@ -117,7 +115,7 @@ public class OrcCommander extends RequestHandler {
```
The Orc King gives the orders and forms the chain.
Then we have the Orc King who gives the orders and forms the chain
```java
public class OrcKing {
@ -137,26 +135,18 @@ public class OrcKing {
}
```
The chain of responsibility in action.
Then it is used as follows
```java
var king = new OrcKing();
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"
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"
```
## Class diagram
![alt text](./etc/chain-of-responsibility.urm.png "Chain of Responsibility class diagram")
![alt text](./etc/chain.urm.png "Chain of Responsibility class diagram")
## Applicability
@ -166,7 +156,7 @@ 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.
## Known uses
## Real world examples
* [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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@ -31,7 +31,7 @@
<artifactId>java-design-patterns</artifactId>
<version>1.25.0-SNAPSHOT</version>
</parent>
<artifactId>chain-of-responsibility</artifactId>
<artifactId>chain</artifactId>
<dependencies>
<dependency>
<groupId>org.junit.jupiter</groupId>

View File

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

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

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

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@ -1,10 +1,9 @@
---
---
layout: pattern
title: Command
folder: command
permalink: /patterns/command/
categories: Behavioral
language: en
tags:
- Gang of Four
---
@ -19,7 +18,7 @@ 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
@ -135,7 +134,7 @@ public class Goblin extends Target {
}
```
Finally, we have the wizard in the main function casting spells.
Finally we have the wizard in main function who casts spell
```java
public static void main(String[] args) {
@ -202,29 +201,32 @@ 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 life
* Specify, queue, and execute requests at different times. A Command object can have a lifetime
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 functionality is achieved by traversing this list backward and forward
calling un-execute and execute, respectively.
Unlimited-level undo and redo is achieved by traversing this list backwards and forwards 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 the disk and re-executing them with
Recovering from a crash involves reloading logged commands from 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 data
changes. 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 changes
to data. 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.
## Known uses
## Typical Use Case
* To keep a history of requests
* Implement callback functionality
* Implement the undo functionality
## Real world examples
* [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)

View File

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

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@ -1,123 +0,0 @@
---
layout: pattern
title: Composite Entity
folder: composite-entity
permalink: /patterns/composite-entity/
categories: Structural
language: en
tags:
- Enterprise Integration Pattern
---
## Intent
It is used to model, represent, and manage a set of persistent objects that are interrelated, rather than representing them as individual fine-grained entities.
## Explanation
Real world example
> For a console, there may be many interfaces that need to be managed and controlled. Using the composite entity pattern, dependent objects such as messages and signals can be combined together and controlled using a single object.
In plain words
> Composite entity pattern allows a set of related objects to be represented and managed by a unified object.
**Programmatic Example**
We need a generic solution for the problem. To achieve this, let's introduce a generic
Composite Entity Pattern.
```java
public abstract class DependentObject<T> {
T data;
public void setData(T message) {
this.data = message;
}
public T getData() {
return data;
}
}
public abstract class CoarseGrainedObject<T> {
DependentObject<T>[] dependentObjects;
public void setData(T... data) {
IntStream.range(0, data.length).forEach(i -> dependentObjects[i].setData(data[i]));
}
public T[] getData() {
return (T[]) Arrays.stream(dependentObjects).map(DependentObject::getData).toArray();
}
}
```
The specialized composite entity `console` inherit from this base class as follows.
```java
public class MessageDependentObject extends DependentObject<String> {
}
public class SignalDependentObject extends DependentObject<String> {
}
public class ConsoleCoarseGrainedObject extends CoarseGrainedObject<String> {
@Override
public String[] getData() {
super.getData();
return new String[]{
dependentObjects[0].getData(), dependentObjects[1].getData()
};
}
public void init() {
dependentObjects = new DependentObject[]{
new MessageDependentObject(), new SignalDependentObject()};
}
}
public class CompositeEntity {
private final ConsoleCoarseGrainedObject console = new ConsoleCoarseGrainedObject();
public void setData(String message, String signal) {
console.setData(message, signal);
}
public String[] getData() {
return console.getData();
}
}
```
Now managing the assignment of message and signal objects with the composite entity `console`.
```java
var console = new CompositeEntity();
console.init();
console.setData("No Danger", "Green Light");
Arrays.stream(console.getData()).forEach(LOGGER::info);
console.setData("Danger", "Red Light");
Arrays.stream(console.getData()).forEach(LOGGER::info);
```
## Class diagram
![alt text](./etc/composite_entity.urm.png "Composite Entity Pattern")
## Applicability
Use the Composite Entity Pattern in the following situation:
* You want to manage multiple dependency objects through one object to adjust the degree of granularity between objects. At the same time, the lifetime of dependency objects depends on a coarse-grained object.
## Credits
* [Composite Entity Pattern in wikipedia](https://en.wikipedia.org/wiki/Composite_entity_pattern)

View File

@ -1,45 +0,0 @@
@startuml
package com.iluwatar.compositeentity {
class App {
+ App(message: String, signal: String)
+ main(args : String[]) {static}
}
class CompositeEntity{
- console : ConsoleCoarseGrainedObject
+ CompositeEntity()
+ setData(message: String, signal: String)
+ getData()
+ init()
}
abstract CoarseGrainedObject{
- dependentObjects : DependentObject[]
+ CoarseGrainedObject()
+ setData(data: T[])
+ getData()
}
abstract DependentObject{
- data : T
+ DependentObject()
+ setData(data: T)
+ getData()
}
class ConsoleCoarseGrainedObject{
+ ConsoleCoarseGrainedObject()
+ getData()
+ init()
}
class MessageDependentObject{
+ MessageDependentObject()
}
class SignalDependentObject{
+ SignalDependentObject()
}
MessageDependentObject --|> DependentObject
SignalDependentObject --|> DependentObject
ConsoleCoarseGrainedObject --|> CoarseGrainedObject
CompositeEntity -right-> ConsoleCoarseGrainedObject
CoarseGrainedObject "1" o--> "0.." DependentObject
App .right.> CompositeEntity
}
@enduml

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@ -1,63 +0,0 @@
<?xml version="1.0" encoding="UTF-8"?>
<!--
The MIT License
Copyright © 2014-2021 Ilkka Seppälä
Permission is hereby granted, free of charge, to any person obtaining a copy
of this software and associated documentation files (the "Software"), to deal
in the Software without restriction, including without limitation the rights
to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
copies of the Software, and to permit persons to whom the Software is
furnished to do so, subject to the following conditions:
The above copyright notice and this permission notice shall be included in
all copies or substantial portions of the Software.
THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
THE SOFTWARE.
-->
<project xmlns="http://maven.apache.org/POM/4.0.0"
xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
<parent>
<artifactId>java-design-patterns</artifactId>
<groupId>com.iluwatar</groupId>
<version>1.25.0-SNAPSHOT</version>
</parent>
<modelVersion>4.0.0</modelVersion>
<artifactId>composite-entity</artifactId>
<dependencies>
<dependency>
<groupId>org.junit.jupiter</groupId>
<artifactId>junit-jupiter-engine</artifactId>
<scope>test</scope>
</dependency>
</dependencies>
<build>
<plugins>
<plugin>
<groupId>org.apache.maven.plugins</groupId>
<artifactId>maven-assembly-plugin</artifactId>
<executions>
<execution>
<configuration>
<archive>
<manifest>
<mainClass>com.iluwatar.composite-entity.com.iluwatar.compositeentity.App</mainClass>
</manifest>
</archive>
</configuration>
</execution>
</executions>
</plugin>
</plugins>
</build>
</project>

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@ -1,61 +0,0 @@
/*
* The MIT License
* Copyright © 2014-2021 Ilkka Seppälä
*
* Permission is hereby granted, free of charge, to any person obtaining a copy
* of this software and associated documentation files (the "Software"), to deal
* in the Software without restriction, including without limitation the rights
* to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
* copies of the Software, and to permit persons to whom the Software is
* furnished to do so, subject to the following conditions:
*
* The above copyright notice and this permission notice shall be included in
* all copies or substantial portions of the Software.
*
* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
* IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
* FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
* AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
* LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
* OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
* THE SOFTWARE.
*/
package com.iluwatar.compositeentity;
import java.util.Arrays;
import lombok.extern.slf4j.Slf4j;
/**
* Composite entity is a Java EE Software design pattern and it is used to model, represent, and
* manage a set of interrelated persistent objects rather than representing them as individual
* fine-grained entity beans, and also a composite entity bean represents a graph of objects.
*/
@Slf4j
public class App {
/**
* An instance that a console manages two related objects.
*/
public App(String message, String signal) {
var console = new CompositeEntity();
console.init();
console.setData(message, signal);
Arrays.stream(console.getData()).forEach(LOGGER::info);
console.setData("Danger", "Red Light");
Arrays.stream(console.getData()).forEach(LOGGER::info);
}
/**
* Program entry point.
*
* @param args command line args
*/
public static void main(String[] args) {
new App("No Danger", "Green Light");
}
}

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@ -1,46 +0,0 @@
/*
* The MIT License
* Copyright © 2014-2021 Ilkka Seppälä
*
* Permission is hereby granted, free of charge, to any person obtaining a copy
* of this software and associated documentation files (the "Software"), to deal
* in the Software without restriction, including without limitation the rights
* to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
* copies of the Software, and to permit persons to whom the Software is
* furnished to do so, subject to the following conditions:
*
* The above copyright notice and this permission notice shall be included in
* all copies or substantial portions of the Software.
*
* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
* IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
* FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
* AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
* LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
* OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
* THE SOFTWARE.
*/
package com.iluwatar.compositeentity;
import java.util.Arrays;
import java.util.stream.IntStream;
/**
* A coarse-grained object is an object with its own life cycle manages its own relationships to
* other objects. It can be an object contained in the composite entity, or, composite entity itself
* can be the coarse-grained object which holds dependent objects.
*/
public abstract class CoarseGrainedObject<T> {
DependentObject<T>[] dependentObjects;
public void setData(T... data) {
IntStream.range(0, data.length).forEach(i -> dependentObjects[i].setData(data[i]));
}
public T[] getData() {
return (T[]) Arrays.stream(dependentObjects).map(DependentObject::getData).toArray();
}
}

View File

@ -1,46 +0,0 @@
/*
* The MIT License
* Copyright © 2014-2021 Ilkka Seppälä
*
* Permission is hereby granted, free of charge, to any person obtaining a copy
* of this software and associated documentation files (the "Software"), to deal
* in the Software without restriction, including without limitation the rights
* to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
* copies of the Software, and to permit persons to whom the Software is
* furnished to do so, subject to the following conditions:
*
* The above copyright notice and this permission notice shall be included in
* all copies or substantial portions of the Software.
*
* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
* IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
* FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
* AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
* LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
* OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
* THE SOFTWARE.
*/
package com.iluwatar.compositeentity;
/**
* Composite entity is the coarse-grained entity bean which may be the coarse-grained object, or may
* contain a reference to the coarse-grained object.
*/
public class CompositeEntity {
private final ConsoleCoarseGrainedObject console = new ConsoleCoarseGrainedObject();
public void setData(String message, String signal) {
console.setData(message, signal);
}
public String[] getData() {
return console.getData();
}
public void init() {
console.init();
}
}

View File

@ -1,43 +0,0 @@
/*
* The MIT License
* Copyright © 2014-2021 Ilkka Seppälä
*
* Permission is hereby granted, free of charge, to any person obtaining a copy
* of this software and associated documentation files (the "Software"), to deal
* in the Software without restriction, including without limitation the rights
* to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
* copies of the Software, and to permit persons to whom the Software is
* furnished to do so, subject to the following conditions:
*
* The above copyright notice and this permission notice shall be included in
* all copies or substantial portions of the Software.
*
* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
* IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
* FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
* AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
* LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
* OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
* THE SOFTWARE.
*/
package com.iluwatar.compositeentity;
/**
* A specific CoarseGrainedObject to implement a console.
*/
public class ConsoleCoarseGrainedObject extends CoarseGrainedObject<String> {
@Override
public String[] getData() {
return new String[]{
dependentObjects[0].getData(), dependentObjects[1].getData()
};
}
public void init() {
dependentObjects = new DependentObject[]{
new MessageDependentObject(), new SignalDependentObject()};
}
}

View File

@ -1,43 +0,0 @@
/*
* The MIT License
* Copyright © 2014-2021 Ilkka Seppälä
*
* Permission is hereby granted, free of charge, to any person obtaining a copy
* of this software and associated documentation files (the "Software"), to deal
* in the Software without restriction, including without limitation the rights
* to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
* copies of the Software, and to permit persons to whom the Software is
* furnished to do so, subject to the following conditions:
*
* The above copyright notice and this permission notice shall be included in
* all copies or substantial portions of the Software.
*
* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
* IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
* FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
* AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
* LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
* OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
* THE SOFTWARE.
*/
package com.iluwatar.compositeentity;
/**
* It is an object, which can contain other dependent objects (there may be a tree of objects within
* the composite entity), that depends on the coarse-grained object and has its life cycle managed
* by the coarse-grained object.
*/
public abstract class DependentObject<T> {
T data;
public void setData(T message) {
this.data = message;
}
public T getData() {
return data;
}
}

View File

@ -1,32 +0,0 @@
/*
* The MIT License
* Copyright © 2014-2021 Ilkka Seppälä
*
* Permission is hereby granted, free of charge, to any person obtaining a copy
* of this software and associated documentation files (the "Software"), to deal
* in the Software without restriction, including without limitation the rights
* to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
* copies of the Software, and to permit persons to whom the Software is
* furnished to do so, subject to the following conditions:
*
* The above copyright notice and this permission notice shall be included in
* all copies or substantial portions of the Software.
*
* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
* IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
* FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
* AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
* LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
* OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
* THE SOFTWARE.
*/
package com.iluwatar.compositeentity;
/**
* The first DependentObject to show message.
*/
public class MessageDependentObject extends DependentObject<String> {
}

View File

@ -1,32 +0,0 @@
/*
* The MIT License
* Copyright © 2014-2021 Ilkka Seppälä
*
* Permission is hereby granted, free of charge, to any person obtaining a copy
* of this software and associated documentation files (the "Software"), to deal
* in the Software without restriction, including without limitation the rights
* to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
* copies of the Software, and to permit persons to whom the Software is
* furnished to do so, subject to the following conditions:
*
* The above copyright notice and this permission notice shall be included in
* all copies or substantial portions of the Software.
*
* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
* IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
* FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
* AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
* LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
* OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
* THE SOFTWARE.
*/
package com.iluwatar.compositeentity;
/**
* The second DependentObject to show message.
*/
public class SignalDependentObject extends DependentObject<String> {
}

View File

@ -1,48 +0,0 @@
/*
* The MIT License
* Copyright © 2014-2021 Ilkka Seppälä
*
* Permission is hereby granted, free of charge, to any person obtaining a copy
* of this software and associated documentation files (the "Software"), to deal
* in the Software without restriction, including without limitation the rights
* to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
* copies of the Software, and to permit persons to whom the Software is
* furnished to do so, subject to the following conditions:
*
* The above copyright notice and this permission notice shall be included in
* all copies or substantial portions of the Software.
*
* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
* IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
* FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
* AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
* LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
* OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
* THE SOFTWARE.
*/
package com.iluwatar.compositeentity;
import static org.junit.jupiter.api.Assertions.assertDoesNotThrow;
import org.junit.jupiter.api.Test;
/**
* com.iluwatar.compositeentity.App running test
*/
class AppTest {
/**
* Issue: Add at least one assertion to this test case.
* <p>
* Solution: Inserted assertion to check whether the execution of the main method in {@link
* App#main(String[])} throws an exception.
*/
@Test
void shouldExecuteApplicationWithoutException() {
assertDoesNotThrow(() -> App.main(new String[]{}));
}
}

View File

@ -1,55 +0,0 @@
/*
* The MIT License
* Copyright © 2014-2021 Ilkka Seppälä
*
* Permission is hereby granted, free of charge, to any person obtaining a copy
* of this software and associated documentation files (the "Software"), to deal
* in the Software without restriction, including without limitation the rights
* to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
* copies of the Software, and to permit persons to whom the Software is
* furnished to do so, subject to the following conditions:
*
* The above copyright notice and this permission notice shall be included in
* all copies or substantial portions of the Software.
*
* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
* IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
* FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
* AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
* LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
* OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
* THE SOFTWARE.
*/
package com.iluwatar.compositeentity;
import org.junit.jupiter.api.Test;
import static org.junit.jupiter.api.Assertions.*;
class PersistenceTest {
final static ConsoleCoarseGrainedObject console = new ConsoleCoarseGrainedObject();
@Test
void dependentObjectChangedForPersistenceTest() {
MessageDependentObject dependentObject = new MessageDependentObject();
console.init();
console.dependentObjects[0] = dependentObject;
String message = "Danger";
assertNull(console.dependentObjects[0].getData());
dependentObject.setData(message);
assertEquals(message, console.dependentObjects[0].getData());
}
@Test
void coarseGrainedObjectChangedForPersistenceTest() {
MessageDependentObject dependentObject = new MessageDependentObject();
console.init();
console.dependentObjects[0] = dependentObject;
String message = "Danger";
assertNull(console.dependentObjects[0].getData());
console.setData(message);
assertEquals(message, dependentObject.getData());
}
}

View File

@ -4,7 +4,6 @@ title: Composite
folder: composite
permalink: /patterns/composite/
categories: Structural
language: en
tags:
- Gang of Four
---
@ -16,15 +15,15 @@ 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 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.
> 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.
In plain words
> Composite pattern lets clients uniformly treat the individual objects.
> Composite pattern lets clients treat the individual objects in a uniform manner.
Wikipedia says
@ -154,22 +153,10 @@ public class Messenger {
And then it can be used as:
```java
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.
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.
```
## Class diagram
@ -184,7 +171,7 @@ 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.
## Known uses
## Real world examples
* [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

@ -45,13 +45,14 @@ 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();
LOGGER.info("Message from the elves: ");
messenger.messageFromElves().print();
var orcMessage = new Messenger().messageFromOrcs();
orcMessage.print();
LOGGER.info("\nMessage from the elves: ");
var elfMessage = new Messenger().messageFromElves();
elfMessage.print();
}
}

View File

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

View File

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

View File

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

View File

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

View File

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

View File

@ -46,7 +46,7 @@ class DataBusTest {
@BeforeEach
void setUp() {
MockitoAnnotations.openMocks(this);
MockitoAnnotations.initMocks(this);
}
@Test

View File

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

View File

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

View File

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

View File

@ -4,9 +4,8 @@ title: Decorator
folder: decorator
permalink: /patterns/decorator/
categories: Structural
language: en
tags:
- Gang of Four
- Gang Of Four
- Extensibility
---
@ -21,9 +20,9 @@ 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.
@ -72,7 +71,7 @@ public class SimpleTroll implements Troll {
}
```
Next, we want to add a club for the troll. We can do it dynamically by using a decorator:
Next we want to add club for the troll. We can do it dynamically by using a decorator:
```java
@Slf4j
@ -106,33 +105,23 @@ Here's the troll in action:
```java
// simple troll
LOGGER.info("A simple looking troll approaches.");
var troll = new SimpleTroll();
troll.attack();
troll.fleeBattle();
LOGGER.info("Simple troll power: {}.\n", troll.getAttackPower());
troll.attack(); // The troll tries to grab you!
troll.fleeBattle(); // The troll shrieks in horror and runs away!
// 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());
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!
```
Program output:
```java
A simple looking troll approaches.
The troll tries to grab you!
The troll shrieks in horror and runs away!
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 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
@ -150,11 +139,11 @@ 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.
## Tutorials
## Tutorial
* [Decorator Pattern Tutorial](https://www.journaldev.com/1540/decorator-design-pattern-in-java-example)
## Known uses
## Real world examples
* [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

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

View File

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

View File

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

View File

@ -1,326 +0,0 @@
---
layout: pattern
title: Domain Model
folder: domain-model
permalink: /patterns/domain-model/
categories: Architectural
language: en
tags:
- Domain
---
## Intent
Domain model pattern provides an object-oriented way of dealing with complicated logic. Instead of having one procedure that handles all business logic for a user action there are multiple objects and each of them handles a slice of domain logic that is relevant to it.
## Explanation
Real world example
> Let's assume that we need to build an e-commerce web application. While analyzing requirements you will notice that there are few nouns you talk about repeatedly. Its your Customer, and a Product the customer looks for. These two are your domain-specific classes and each of that classes will include some business logic specific to its domain.
In plain words
> The Domain Model is an object model of the domain that incorporates both behavior and data.
Programmatic Example
In the example of the e-commerce app, we need to deal with the domain logic of customers who want to buy products and return them if they want. We can use the domain model pattern and create classes `Customer` and `Product` where every single instance of that class incorporates both behavior and data and represents only one record in the underlying table.
Here is the `Product` domain class with fields `name`, `price`, `expirationDate` which is specific for each product, `productDao` for working with DB, `save` method for saving product and `getSalePrice` method which return price for this product with discount.
```java
@Slf4j
@Getter
@Setter
@Builder
@AllArgsConstructor
public class Product {
private static final int DAYS_UNTIL_EXPIRATION_WHEN_DISCOUNT_ACTIVE = 4;
private static final double DISCOUNT_RATE = 0.2;
@NonNull private final ProductDao productDao;
@NonNull private String name;
@NonNull private Money price;
@NonNull private LocalDate expirationDate;
/**
* Save product or update if product already exist.
*/
public void save() {
try {
Optional<Product> product = productDao.findByName(name);
if (product.isPresent()) {
productDao.update(this);
} else {
productDao.save(this);
}
} catch (SQLException ex) {
LOGGER.error(ex.getMessage());
}
}
/**
* Calculate sale price of product with discount.
*/
public Money getSalePrice() {
return price.minus(calculateDiscount());
}
private Money calculateDiscount() {
if (ChronoUnit.DAYS.between(LocalDate.now(), expirationDate)
< DAYS_UNTIL_EXPIRATION_WHEN_DISCOUNT_ACTIVE) {
return price.multipliedBy(DISCOUNT_RATE, RoundingMode.DOWN);
}
return Money.zero(USD);
}
}
```
Here is the `Customer` domain class with fields `name`, `money` which is specific for each customer, `customerDao` for working with DB, `save` for saving customer, `buyProduct` which add a product to purchases and withdraw money, `returnProduct` which remove product from purchases and return money, `showPurchases` and `showBalance` methods for printing customer's purchases and money balance.
```java
@Slf4j
@Getter
@Setter
@Builder
public class Customer {
@NonNull private final CustomerDao customerDao;
@Builder.Default private List<Product> purchases = new ArrayList<>();
@NonNull private String name;
@NonNull private Money money;
/**
* Save customer or update if customer already exist.
*/
public void save() {
try {
Optional<Customer> customer = customerDao.findByName(name);
if (customer.isPresent()) {
customerDao.update(this);
} else {
customerDao.save(this);
}
} catch (SQLException ex) {
LOGGER.error(ex.getMessage());
}
}
/**
* Add product to purchases, save to db and withdraw money.
*
* @param product to buy.
*/
public void buyProduct(Product product) {
LOGGER.info(
String.format(
"%s want to buy %s($%.2f)...",
name, product.getName(), product.getSalePrice().getAmount()));
try {
withdraw(product.getSalePrice());
} catch (IllegalArgumentException ex) {
LOGGER.error(ex.getMessage());
return;
}
try {
customerDao.addProduct(product, this);
purchases.add(product);
LOGGER.info(String.format("%s bought %s!", name, product.getName()));
} catch (SQLException exception) {
receiveMoney(product.getSalePrice());
LOGGER.error(exception.getMessage());
}
}
/**
* Remove product from purchases, delete from db and return money.
*
* @param product to return.
*/
public void returnProduct(Product product) {
LOGGER.info(
String.format(
"%s want to return %s($%.2f)...",
name, product.getName(), product.getSalePrice().getAmount()));
if (purchases.contains(product)) {
try {
customerDao.deleteProduct(product, this);
purchases.remove(product);
receiveMoney(product.getSalePrice());
LOGGER.info(String.format("%s returned %s!", name, product.getName()));
} catch (SQLException ex) {
LOGGER.error(ex.getMessage());
}
} else {
LOGGER.error(String.format("%s didn't buy %s...", name, product.getName()));
}
}
/**
* Print customer's purchases.
*/
public void showPurchases() {
Optional<String> purchasesToShow =
purchases.stream()
.map(p -> p.getName() + " - $" + p.getSalePrice().getAmount())
.reduce((p1, p2) -> p1 + ", " + p2);
if (purchasesToShow.isPresent()) {
LOGGER.info(name + " bought: " + purchasesToShow.get());
} else {
LOGGER.info(name + " didn't bought anything");
}
}
/**
* Print customer's money balance.
*/
public void showBalance() {
LOGGER.info(name + " balance: " + money);
}
private void withdraw(Money amount) throws IllegalArgumentException {
if (money.compareTo(amount) < 0) {
throw new IllegalArgumentException("Not enough money!");
}
money = money.minus(amount);
}
private void receiveMoney(Money amount) {
money = money.plus(amount);
}
}
```
In the class `App`, we create a new instance of class Customer which represents customer Tom and handle data and actions of that customer and creating three products that Tom wants to buy.
```java
// Create data source and create the customers, products and purchases tables
final var dataSource = createDataSource();
deleteSchema(dataSource);
createSchema(dataSource);
// create customer
var customerDao = new CustomerDaoImpl(dataSource);
var tom =
Customer.builder()
.name("Tom")
.money(Money.of(USD, 30))
.customerDao(customerDao)
.build();
tom.save();
// create products
var productDao = new ProductDaoImpl(dataSource);
var eggs =
Product.builder()
.name("Eggs")
.price(Money.of(USD, 10.0))
.expirationDate(LocalDate.now().plusDays(7))
.productDao(productDao)
.build();
var butter =
Product.builder()
.name("Butter")
.price(Money.of(USD, 20.00))
.expirationDate(LocalDate.now().plusDays(9))
.productDao(productDao)
.build();
var cheese =
Product.builder()
.name("Cheese")
.price(Money.of(USD, 25.0))
.expirationDate(LocalDate.now().plusDays(2))
.productDao(productDao)
.build();
eggs.save();
butter.save();
cheese.save();
// show money balance of customer after each purchase
tom.showBalance();
tom.showPurchases();
// buy eggs
tom.buyProduct(eggs);
tom.showBalance();
// buy butter
tom.buyProduct(butter);
tom.showBalance();
// trying to buy cheese, but receive a refusal
// because he didn't have enough money
tom.buyProduct(cheese);
tom.showBalance();
// return butter and get money back
tom.returnProduct(butter);
tom.showBalance();
// Tom can buy cheese now because he has enough money
// and there is a discount on cheese because it expires in 2 days
tom.buyProduct(cheese);
tom.save();
// show money balance and purchases after shopping
tom.showBalance();
tom.showPurchases();
```
The program output:
```java
17:52:28.690 [main] INFO com.iluwatar.domainmodel.Customer - Tom balance: USD 30.00
17:52:28.695 [main] INFO com.iluwatar.domainmodel.Customer - Tom didn't bought anything
17:52:28.699 [main] INFO com.iluwatar.domainmodel.Customer - Tom want to buy Eggs($10.00)...
17:52:28.705 [main] INFO com.iluwatar.domainmodel.Customer - Tom bought Eggs!
17:52:28.705 [main] INFO com.iluwatar.domainmodel.Customer - Tom balance: USD 20.00
17:52:28.705 [main] INFO com.iluwatar.domainmodel.Customer - Tom want to buy Butter($20.00)...
17:52:28.712 [main] INFO com.iluwatar.domainmodel.Customer - Tom bought Butter!
17:52:28.712 [main] INFO com.iluwatar.domainmodel.Customer - Tom balance: USD 0.00
17:52:28.712 [main] INFO com.iluwatar.domainmodel.Customer - Tom want to buy Cheese($20.00)...
17:52:28.712 [main] ERROR com.iluwatar.domainmodel.Customer - Not enough money!
17:52:28.712 [main] INFO com.iluwatar.domainmodel.Customer - Tom balance: USD 0.00
17:52:28.712 [main] INFO com.iluwatar.domainmodel.Customer - Tom want to return Butter($20.00)...
17:52:28.721 [main] INFO com.iluwatar.domainmodel.Customer - Tom returned Butter!
17:52:28.721 [main] INFO com.iluwatar.domainmodel.Customer - Tom balance: USD 20.00
17:52:28.721 [main] INFO com.iluwatar.domainmodel.Customer - Tom want to buy Cheese($20.00)...
17:52:28.726 [main] INFO com.iluwatar.domainmodel.Customer - Tom bought Cheese!
17:52:28.737 [main] INFO com.iluwatar.domainmodel.Customer - Tom balance: USD 0.00
17:52:28.738 [main] INFO com.iluwatar.domainmodel.Customer - Tom bought: Eggs - $10.00, Cheese - $20.00
```
## Class diagram
![](./etc/domain-model.urm.png "domain model")
## Applicability
Use a Domain model pattern when your domain logic is complex and that complexity can rapidly grow because this pattern handles increasing complexity very well. Otherwise, it's a more complex solution for organizing domain logic, so shouldn't use Domain Model pattern for systems with simple domain logic, because the cost of understanding it and complexity of data source exceeds the benefit of this pattern.
## Related patterns
- [Transaction Script](https://java-design-patterns.com/patterns/transaction-script/)
- [Table Module](https://java-design-patterns.com/patterns/table-module/)
- [Service Layer](https://java-design-patterns.com/patterns/service-layer/)
## Credits
* [Domain Model Pattern](https://martinfowler.com/eaaCatalog/domainModel.html)
* [Patterns of Enterprise Application Architecture](https://www.amazon.com/gp/product/0321127420/ref=as_li_qf_asin_il_tl?ie=UTF8&tag=javadesignpat-20&creative=9325&linkCode=as2&creativeASIN=0321127420&linkId=18acc13ba60d66690009505577c45c04)
* [Architecture patterns: domain model and friends](https://inviqa.com/blog/architecture-patterns-domain-model-and-friends)

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@startuml
package com.iluwatar.domainmodel {
class App {
+ CREATE_SCHEMA_SQL : String {static}
+ DELETE_SCHEMA_SQL : String {static}
+ H2_DB_URL : String {static}
+ App()
- createDataSource() : DataSource {static}
- createSchema(dataSource : DataSource) {static}
- deleteSchema(dataSource : DataSource) {static}
+ main(args : String[]) {static}
}
class Customer {
- customerDao : CustomerDao
- money : Money
- name : String
- purchases : List<Product>
~ Customer(customerDao : CustomerDao, purchases : List<Product>, name : String, money : Money)
+ builder() : CustomerBuilder {static}
+ buyProduct(product : Product)
+ getCustomerDao() : CustomerDao
+ getMoney() : Money
+ getName() : String
+ getPurchases() : List<Product>
- receiveMoney(amount : Money)
+ returnProduct(product : Product)
+ save()
+ setMoney(money : Money)
+ setName(name : String)
+ setPurchases(purchases : List<Product>)
+ showBalance()
+ showPurchases()
- withdraw(amount : Money)
}
interface CustomerDao {
+ addProduct(Product, Customer) {abstract}
+ deleteProduct(Product, Customer) {abstract}
+ findByName(String) : Optional<Customer> {abstract}
+ save(Customer) {abstract}
+ update(Customer) {abstract}
}
class CustomerDaoImpl {
- dataSource : DataSource
+ CustomerDaoImpl(userDataSource : DataSource)
+ addProduct(product : Product, customer : Customer)
+ deleteProduct(product : Product, customer : Customer)
+ findByName(name : String) : Optional<Customer>
+ save(customer : Customer)
+ update(customer : Customer)
}
class Product {
- expirationDate : LocalDate
- name : String
- price : Money
- productDao : ProductDao
+ Product(productDao : ProductDao, name : String, price : Money, expirationDate : LocalDate)
+ builder() : ProductBuilder {static}
- calculateDiscount() : Money
+ getExpirationDate() : LocalDate
+ getName() : String
+ getPrice() : Money
+ getProductDao() : ProductDao
+ getSalePrice() : Money
+ save()
+ setExpirationDate(expirationDate : LocalDate)
+ setName(name : String)
+ setPrice(price : Money)
}
interface ProductDao {
+ findByName(String) : Optional<Product> {abstract}
+ save(Product) {abstract}
+ update(Product) {abstract}
}
class ProductDaoImpl {
- dataSource : DataSource
+ ProductDaoImpl(userDataSource : DataSource)
+ findByName(name : String) : Optional<Product>
+ save(product : Product)
+ update(product : Product)
}
}
Product --> ProductDao
Customer --> CustomerDao
Customer --> Product
CustomerDaoImpl ..|> CustomerDao
ProductDaoImpl ..|> ProductDao
@enduml

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@ -1,78 +0,0 @@
<?xml version="1.0" encoding="UTF-8"?>
<!--
The MIT License
Copyright © 2014-2021 Ilkka Seppälä
Permission is hereby granted, free of charge, to any person obtaining a copy
of this software and associated documentation files (the "Software"), to deal
in the Software without restriction, including without limitation the rights
to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
copies of the Software, and to permit persons to whom the Software is
furnished to do so, subject to the following conditions:
The above copyright notice and this permission notice shall be included in
all copies or substantial portions of the Software.
THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
THE SOFTWARE.
-->
<project xmlns="http://maven.apache.org/POM/4.0.0"
xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
<parent>
<artifactId>java-design-patterns</artifactId>
<groupId>com.iluwatar</groupId>
<version>1.25.0-SNAPSHOT</version>
</parent>
<modelVersion>4.0.0</modelVersion>
<artifactId>domain-model</artifactId>
<dependencies>
<dependency>
<groupId>com.h2database</groupId>
<artifactId>h2</artifactId>
</dependency>
<dependency>
<groupId>org.junit.jupiter</groupId>
<artifactId>junit-jupiter-engine</artifactId>
<scope>test</scope>
</dependency>
<dependency>
<groupId>org.mockito</groupId>
<artifactId>mockito-core</artifactId>
</dependency>
<dependency>
<groupId>org.joda</groupId>
<artifactId>joda-money</artifactId>
<version>1.0.1</version>
</dependency>
</dependencies>
<build>
<plugins>
<plugin>
<groupId>org.apache.maven.plugins</groupId>
<artifactId>maven-assembly-plugin</artifactId>
<executions>
<execution>
<configuration>
<archive>
<manifest>
<mainClass>com.iluwatar.domainmodel.App</mainClass>
</manifest>
</archive>
</configuration>
</execution>
</executions>
</plugin>
</plugins>
</build>
</project>

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@ -1,173 +0,0 @@
/*
* The MIT License
* Copyright © 2014-2021 Ilkka Seppälä
*
* Permission is hereby granted, free of charge, to any person obtaining a copy
* of this software and associated documentation files (the "Software"), to deal
* in the Software without restriction, including without limitation the rights
* to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
* copies of the Software, and to permit persons to whom the Software is
* furnished to do so, subject to the following conditions:
*
* The above copyright notice and this permission notice shall be included in
* all copies or substantial portions of the Software.
*
* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
* IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
* FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
* AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
* LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
* OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
* THE SOFTWARE.
*/
package com.iluwatar.domainmodel;
import static org.joda.money.CurrencyUnit.USD;
import java.sql.SQLException;
import java.time.LocalDate;
import javax.sql.DataSource;
import org.h2.jdbcx.JdbcDataSource;
import org.joda.money.Money;
/**
* Domain Model pattern is a more complex solution for organizing domain logic than Transaction
* Script and Table Module. It provides an object-oriented way of dealing with complicated logic.
* Instead of having one procedure that handles all business logic for a user action like
* Transaction Script there are multiple objects and each of them handles a slice of domain logic
* that is relevant to it. The significant difference between Domain Model and Table Module pattern
* is that in Table Module a single class encapsulates all the domain logic for all records stored
* in table when in Domain Model every single class represents only one record in underlying table.
*
* <p>In this example, we will use the Domain Model pattern to implement buying of products
* by customers in a Shop. The main method will create a customer and a few products.
* Customer will do a few purchases, try to buy product which are too expensive for him,
* return product which he bought to return money.</p>
*/
public class App {
public static final String H2_DB_URL = "jdbc:h2:~/test";
public static final String CREATE_SCHEMA_SQL =
"CREATE TABLE CUSTOMERS (name varchar primary key, money decimal);"
+ "CREATE TABLE PRODUCTS (name varchar primary key, price decimal, expiration_date date);"
+ "CREATE TABLE PURCHASES ("
+ "product_name varchar references PRODUCTS(name),"
+ "customer_name varchar references CUSTOMERS(name));";
public static final String DELETE_SCHEMA_SQL =
"DROP TABLE CUSTOMERS IF EXISTS;"
+ "DROP TABLE PURCHASES IF EXISTS;"
+ "DROP TABLE PRODUCTS IF EXISTS;";
/**
* Program entry point.
*
* @param args command line arguments
* @throws Exception if any error occurs
*/
public static void main(String[] args) throws Exception {
// Create data source and create the customers, products and purchases tables
final var dataSource = createDataSource();
deleteSchema(dataSource);
createSchema(dataSource);
// create customer
var customerDao = new CustomerDaoImpl(dataSource);
var tom =
Customer.builder()
.name("Tom")
.money(Money.of(USD, 30))
.customerDao(customerDao)
.build();
tom.save();
// create products
var productDao = new ProductDaoImpl(dataSource);
var eggs =
Product.builder()
.name("Eggs")
.price(Money.of(USD, 10.0))
.expirationDate(LocalDate.now().plusDays(7))
.productDao(productDao)
.build();
var butter =
Product.builder()
.name("Butter")
.price(Money.of(USD, 20.00))
.expirationDate(LocalDate.now().plusDays(9))
.productDao(productDao)
.build();
var cheese =
Product.builder()
.name("Cheese")
.price(Money.of(USD, 25.0))
.expirationDate(LocalDate.now().plusDays(2))
.productDao(productDao)
.build();
eggs.save();
butter.save();
cheese.save();
// show money balance of customer after each purchase
tom.showBalance();
tom.showPurchases();
// buy eggs
tom.buyProduct(eggs);
tom.showBalance();
// buy butter
tom.buyProduct(butter);
tom.showBalance();
// trying to buy cheese, but receive a refusal
// because he didn't have enough money
tom.buyProduct(cheese);
tom.showBalance();
// return butter and get money back
tom.returnProduct(butter);
tom.showBalance();
// Tom can buy cheese now because he has enough money
// and there is a discount on cheese because it expires in 2 days
tom.buyProduct(cheese);
tom.save();
// show money balance and purchases after shopping
tom.showBalance();
tom.showPurchases();
}
private static DataSource createDataSource() {
var dataSource = new JdbcDataSource();
dataSource.setUrl(H2_DB_URL);
return dataSource;
}
private static void deleteSchema(DataSource dataSource) throws SQLException {
try (var connection = dataSource.getConnection();
var statement = connection.createStatement()) {
statement.execute(DELETE_SCHEMA_SQL);
}
}
private static void createSchema(DataSource dataSource) throws SQLException {
try (var connection = dataSource.getConnection();
var statement = connection.createStatement()) {
statement.execute(CREATE_SCHEMA_SQL);
}
}
}

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@ -1,153 +0,0 @@
/*
* The MIT License
* Copyright © 2014-2021 Ilkka Seppälä
*
* Permission is hereby granted, free of charge, to any person obtaining a copy
* of this software and associated documentation files (the "Software"), to deal
* in the Software without restriction, including without limitation the rights
* to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
* copies of the Software, and to permit persons to whom the Software is
* furnished to do so, subject to the following conditions:
*
* The above copyright notice and this permission notice shall be included in
* all copies or substantial portions of the Software.
*
* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
* IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
* FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
* AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
* LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
* OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
* THE SOFTWARE.
*/
package com.iluwatar.domainmodel;
import java.sql.SQLException;
import java.util.ArrayList;
import java.util.List;
import java.util.Optional;
import lombok.Builder;
import lombok.Getter;
import lombok.NonNull;
import lombok.Setter;
import lombok.extern.slf4j.Slf4j;
import org.joda.money.Money;
/**
* This class organizes domain logic of customer.
* A single instance of this class
* contains both the data and behavior of a single customer.
*/
@Slf4j
@Getter
@Setter
@Builder
public class Customer {
@NonNull private final CustomerDao customerDao;
@Builder.Default private List<Product> purchases = new ArrayList<>();
@NonNull private String name;
@NonNull private Money money;
/**
* Save customer or update if customer already exist.
*/
public void save() {
try {
Optional<Customer> customer = customerDao.findByName(name);
if (customer.isPresent()) {
customerDao.update(this);
} else {
customerDao.save(this);
}
} catch (SQLException ex) {
LOGGER.error(ex.getMessage());
}
}
/**
* Add product to purchases, save to db and withdraw money.
*
* @param product to buy.
*/
public void buyProduct(Product product) {
LOGGER.info(
String.format(
"%s want to buy %s($%.2f)...",
name, product.getName(), product.getSalePrice().getAmount()));
try {
withdraw(product.getSalePrice());
} catch (IllegalArgumentException ex) {
LOGGER.error(ex.getMessage());
return;
}
try {
customerDao.addProduct(product, this);
purchases.add(product);
LOGGER.info(String.format("%s bought %s!", name, product.getName()));
} catch (SQLException exception) {
receiveMoney(product.getSalePrice());
LOGGER.error(exception.getMessage());
}
}
/**
* Remove product from purchases, delete from db and return money.
*
* @param product to return.
*/
public void returnProduct(Product product) {
LOGGER.info(
String.format(
"%s want to return %s($%.2f)...",
name, product.getName(), product.getSalePrice().getAmount()));
if (purchases.contains(product)) {
try {
customerDao.deleteProduct(product, this);
purchases.remove(product);
receiveMoney(product.getSalePrice());
LOGGER.info(String.format("%s returned %s!", name, product.getName()));
} catch (SQLException ex) {
LOGGER.error(ex.getMessage());
}
} else {
LOGGER.error(String.format("%s didn't buy %s...", name, product.getName()));
}
}
/**
* Print customer's purchases.
*/
public void showPurchases() {
Optional<String> purchasesToShow =
purchases.stream()
.map(p -> p.getName() + " - $" + p.getSalePrice().getAmount())
.reduce((p1, p2) -> p1 + ", " + p2);
if (purchasesToShow.isPresent()) {
LOGGER.info(name + " bought: " + purchasesToShow.get());
} else {
LOGGER.info(name + " didn't bought anything");
}
}
/**
* Print customer's money balance.
*/
public void showBalance() {
LOGGER.info(name + " balance: " + money);
}
private void withdraw(Money amount) throws IllegalArgumentException {
if (money.compareTo(amount) < 0) {
throw new IllegalArgumentException("Not enough money!");
}
money = money.minus(amount);
}
private void receiveMoney(Money amount) {
money = money.plus(amount);
}
}

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@ -1,40 +0,0 @@
/*
* The MIT License
* Copyright © 2014-2021 Ilkka Seppälä
*
* Permission is hereby granted, free of charge, to any person obtaining a copy
* of this software and associated documentation files (the "Software"), to deal
* in the Software without restriction, including without limitation the rights
* to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
* copies of the Software, and to permit persons to whom the Software is
* furnished to do so, subject to the following conditions:
*
* The above copyright notice and this permission notice shall be included in
* all copies or substantial portions of the Software.
*
* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
* IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
* FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
* AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
* LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
* OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
* THE SOFTWARE.
*/
package com.iluwatar.domainmodel;
import java.sql.SQLException;
import java.util.Optional;
public interface CustomerDao {
Optional<Customer> findByName(String name) throws SQLException;
void update(Customer customer) throws SQLException;
void save(Customer customer) throws SQLException;
void addProduct(Product product, Customer customer) throws SQLException;
void deleteProduct(Product product, Customer customer) throws SQLException;
}

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@ -1,109 +0,0 @@
/*
* The MIT License
* Copyright © 2014-2021 Ilkka Seppälä
*
* Permission is hereby granted, free of charge, to any person obtaining a copy
* of this software and associated documentation files (the "Software"), to deal
* in the Software without restriction, including without limitation the rights
* to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
* copies of the Software, and to permit persons to whom the Software is
* furnished to do so, subject to the following conditions:
*
* The above copyright notice and this permission notice shall be included in
* all copies or substantial portions of the Software.
*
* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
* IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
* FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
* AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
* LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
* OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
* THE SOFTWARE.
*/
package com.iluwatar.domainmodel;
import static org.joda.money.CurrencyUnit.USD;
import java.sql.ResultSet;
import java.sql.SQLException;
import java.util.Optional;
import javax.sql.DataSource;
import org.joda.money.Money;
public class CustomerDaoImpl implements CustomerDao {
private final DataSource dataSource;
public CustomerDaoImpl(final DataSource userDataSource) {
this.dataSource = userDataSource;
}
@Override
public Optional<Customer> findByName(String name) throws SQLException {
var sql = "select * from CUSTOMERS where name = ?;";
try (var connection = dataSource.getConnection();
var preparedStatement = connection.prepareStatement(sql)) {
preparedStatement.setString(1, name);
ResultSet rs = preparedStatement.executeQuery();
if (rs.next()) {
return Optional.of(
Customer.builder()
.name(rs.getString("name"))
.money(Money.of(USD, rs.getBigDecimal("money")))
.customerDao(this)
.build());
} else {
return Optional.empty();
}
}
}
@Override
public void update(Customer customer) throws SQLException {
var sql = "update CUSTOMERS set money = ? where name = ?;";
try (var connection = dataSource.getConnection();
var preparedStatement = connection.prepareStatement(sql)) {
preparedStatement.setBigDecimal(1, customer.getMoney().getAmount());
preparedStatement.setString(2, customer.getName());
preparedStatement.executeUpdate();
}
}
@Override
public void save(Customer customer) throws SQLException {
var sql = "insert into CUSTOMERS (name, money) values (?, ?)";
try (var connection = dataSource.getConnection();
var preparedStatement = connection.prepareStatement(sql)) {
preparedStatement.setString(1, customer.getName());
preparedStatement.setBigDecimal(2, customer.getMoney().getAmount());
preparedStatement.executeUpdate();
}
}
@Override
public void addProduct(Product product, Customer customer) throws SQLException {
var sql = "insert into PURCHASES (product_name, customer_name) values (?,?)";
try (var connection = dataSource.getConnection();
var preparedStatement = connection.prepareStatement(sql)) {
preparedStatement.setString(1, product.getName());
preparedStatement.setString(2, customer.getName());
preparedStatement.executeUpdate();
}
}
@Override
public void deleteProduct(Product product, Customer customer) throws SQLException {
var sql = "delete from PURCHASES where product_name = ? and customer_name = ?";
try (var connection = dataSource.getConnection();
var preparedStatement = connection.prepareStatement(sql)) {
preparedStatement.setString(1, product.getName());
preparedStatement.setString(2, customer.getName());
preparedStatement.executeUpdate();
}
}
}

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