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task: Explanations and grammar fixes for all the GoF patterns (#1791)

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* Grammatical fixes to command pattern

* Update bridge pattern readme

* Fixes to builder pattern grammar

* Update chain of responsibility

* Improvements to the composite example

* Fixes to headings

* Minor updates to decorator pattern

* Update facade

* Update factory example

* Update factory method

* Update flyweight

* Interpreter explanation

* Update iterator readme

* Add explanation for mediator pattern

* Grammatical fixes to memento

* Grammar fixes for observer

* Update explanation for the prototype pattern

* Proxy pattern grammar fixes

* Update singleton

* Grammar fixes to state pattern

* Grammar fixes for strategy

* Grammar fixes, template method

* Grammar fixes for visitor

* Fix typo
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Ilkka Seppälä
2021-06-24 15:57:20 +03:00
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commit 04bf566dc1
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---
layout: pattern
title: Chain of responsibility
folder: chain-of-responsibility
permalink: /patterns/chain-of-responsibility/
categories: Behavioral
language: en
tags:
- Gang of Four
---
## Intent
Avoid coupling the sender of a request to its receiver by giving more than one object a chance to
handle the request. Chain the receiving objects and pass the request along the chain until an object
handles it.
## Explanation
Real-world example
> 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.
In plain words
> It helps to build a chain of objects. A request enters from one end and keeps going from an object
> to another until it finds a suitable handler.
Wikipedia says
> In object-oriented design, the chain-of-responsibility pattern is a design pattern consisting of
> a source of command objects and a series of processing objects. Each processing object contains
> logic that defines the types of command objects that it can handle; the rest are passed to the
> next processing object in the chain.
**Programmatic Example**
Translating our example with the orcs from above. First, we have the `Request` class:
```java
public class Request {
private final RequestType requestType;
private final String requestDescription;
private boolean handled;
public Request(final RequestType requestType, final String requestDescription) {
this.requestType = Objects.requireNonNull(requestType);
this.requestDescription = Objects.requireNonNull(requestDescription);
}
public String getRequestDescription() { return requestDescription; }
public RequestType getRequestType() { return requestType; }
public void markHandled() { this.handled = true; }
public boolean isHandled() { return this.handled; }
@Override
public String toString() { return getRequestDescription(); }
}
public enum RequestType {
DEFEND_CASTLE, TORTURE_PRISONER, COLLECT_TAX
}
```
Next, we show the request handler hierarchy.
```java
@Slf4j
public abstract class RequestHandler {
private final RequestHandler next;
public RequestHandler(RequestHandler next) {
this.next = next;
}
public void handleRequest(Request req) {
if (next != null) {
next.handleRequest(req);
}
}
protected void printHandling(Request req) {
LOGGER.info("{} handling request \"{}\"", this, req);
}
@Override
public abstract String toString();
}
public class OrcCommander extends RequestHandler {
public OrcCommander(RequestHandler handler) {
super(handler);
}
@Override
public void handleRequest(Request req) {
if (req.getRequestType().equals(RequestType.DEFEND_CASTLE)) {
printHandling(req);
req.markHandled();
} else {
super.handleRequest(req);
}
}
@Override
public String toString() {
return "Orc commander";
}
}
// OrcOfficer and OrcSoldier are defined similarly as OrcCommander
```
The Orc King gives the orders and forms the chain.
```java
public class OrcKing {
RequestHandler chain;
public OrcKing() {
buildChain();
}
private void buildChain() {
chain = new OrcCommander(new OrcOfficer(new OrcSoldier(null)));
}
public void makeRequest(Request req) {
chain.handleRequest(req);
}
}
```
The chain of responsibility in action.
```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"
```
## Class diagram
![alt text](./etc/chain-of-responsibility.urm.png "Chain of Responsibility class diagram")
## Applicability
Use Chain of Responsibility when
* More than one object may handle a request, and the handler isn't known a priori. The handler should be ascertained automatically.
* You want to issue a request to one of several objects without specifying the receiver explicitly.
* The set of objects that can handle a request should be specified dynamically.
## Known uses
* [java.util.logging.Logger#log()](http://docs.oracle.com/javase/8/docs/api/java/util/logging/Logger.html#log%28java.util.logging.Level,%20java.lang.String%29)
* [Apache Commons Chain](https://commons.apache.org/proper/commons-chain/index.html)
* [javax.servlet.Filter#doFilter()](http://docs.oracle.com/javaee/7/api/javax/servlet/Filter.html#doFilter-javax.servlet.ServletRequest-javax.servlet.ServletResponse-javax.servlet.FilterChain-)
## Credits
* [Design Patterns: Elements of Reusable Object-Oriented Software](https://www.amazon.com/gp/product/0201633612/ref=as_li_tl?ie=UTF8&camp=1789&creative=9325&creativeASIN=0201633612&linkCode=as2&tag=javadesignpat-20&linkId=675d49790ce11db99d90bde47f1aeb59)
* [Head First Design Patterns: A Brain-Friendly Guide](https://www.amazon.com/gp/product/0596007124/ref=as_li_tl?ie=UTF8&camp=1789&creative=9325&creativeASIN=0596007124&linkCode=as2&tag=javadesignpat-20&linkId=6b8b6eea86021af6c8e3cd3fc382cb5b)

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@startuml
package com.iluwatar.chain {
class App {
+ App()
+ main(args : String[]) {static}
}
class OrcCommander {
+ OrcCommander(handler : RequestHandler)
+ handleRequest(req : Request)
+ toString() : String
}
class OrcKing {
- chain : RequestHandler
+ OrcKing()
- buildChain()
+ makeRequest(req : Request)
}
class OrcOfficer {
+ OrcOfficer(handler : RequestHandler)
+ handleRequest(req : Request)
+ toString() : String
}
class OrcSoldier {
+ OrcSoldier(handler : RequestHandler)
+ handleRequest(req : Request)
+ toString() : String
}
class Request {
- handled : boolean
- requestDescription : String
- requestType : RequestType
+ Request(requestType : RequestType, requestDescription : String)
+ getRequestDescription() : String
+ getRequestType() : RequestType
+ isHandled() : boolean
+ markHandled()
+ toString() : String
}
abstract class RequestHandler {
- LOGGER : Logger {static}
- next : RequestHandler
+ RequestHandler(next : RequestHandler)
+ handleRequest(req : Request)
# printHandling(req : Request)
+ toString() : String {abstract}
}
enum RequestType {
+ COLLECT_TAX {static}
+ DEFEND_CASTLE {static}
+ TORTURE_PRISONER {static}
+ valueOf(name : String) : RequestType {static}
+ values() : RequestType[] {static}
}
}
OrcKing --> "-chain" RequestHandler
RequestHandler --> "-next" RequestHandler
Request --> "-requestType" RequestType
OrcCommander --|> RequestHandler
OrcOfficer --|> RequestHandler
OrcSoldier --|> RequestHandler
@enduml

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<?xml version="1.0"?>
<!--
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.
-->
<project xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd" xmlns="http://maven.apache.org/POM/4.0.0"
xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance">
<modelVersion>4.0.0</modelVersion>
<parent>
<groupId>com.iluwatar</groupId>
<artifactId>java-design-patterns</artifactId>
<version>1.25.0-SNAPSHOT</version>
</parent>
<artifactId>chain-of-responsibility</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.chain.App</mainClass>
</manifest>
</archive>
</configuration>
</execution>
</executions>
</plugin>
</plugins>
</build>
</project>

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/*
* 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.chain;
/**
* The Chain of Responsibility pattern is a design pattern consisting of command objects and a
* series of processing objects. Each processing object contains logic that defines the types of
* command objects that it can handle; the rest are passed to the next processing object in the
* chain. A mechanism also exists for adding new processing objects to the end of this chain.
*
* <p>In this example we organize the request handlers ({@link RequestHandler}) into a chain where
* each handler has a chance to act on the request on its turn. Here the king ({@link OrcKing})
* makes requests and the military orcs ({@link OrcCommander}, {@link OrcOfficer}, {@link
* OrcSoldier}) form the handler chain.
*/
public class App {
/**
* Program entry point.
*
* @param args command line args
*/
public static void main(String[] args) {
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"));
}
}

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/*
* 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.chain;
/**
* OrcCommander.
*/
public class OrcCommander extends RequestHandler {
public OrcCommander(RequestHandler handler) {
super(handler);
}
@Override
public void handleRequest(Request req) {
if (RequestType.DEFEND_CASTLE == req.getRequestType()) {
printHandling(req);
req.markHandled();
} else {
super.handleRequest(req);
}
}
@Override
public String toString() {
return "Orc commander";
}
}

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/*
* 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.chain;
/**
* OrcKing makes requests that are handled by the chain.
*/
public class OrcKing {
private RequestHandler chain;
public OrcKing() {
buildChain();
}
private void buildChain() {
chain = new OrcCommander(new OrcOfficer(new OrcSoldier(null)));
}
public void makeRequest(Request req) {
chain.handleRequest(req);
}
}

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/*
* 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.chain;
/**
* OrcOfficer.
*/
public class OrcOfficer extends RequestHandler {
public OrcOfficer(RequestHandler handler) {
super(handler);
}
@Override
public void handleRequest(Request req) {
if (RequestType.TORTURE_PRISONER == req.getRequestType()) {
printHandling(req);
req.markHandled();
} else {
super.handleRequest(req);
}
}
@Override
public String toString() {
return "Orc officer";
}
}

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/*
* 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.chain;
/**
* OrcSoldier.
*/
public class OrcSoldier extends RequestHandler {
public OrcSoldier(RequestHandler handler) {
super(handler);
}
@Override
public void handleRequest(Request req) {
if (RequestType.COLLECT_TAX == req.getRequestType()) {
printHandling(req);
req.markHandled();
} else {
super.handleRequest(req);
}
}
@Override
public String toString() {
return "Orc soldier";
}
}

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/*
* 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.chain;
import java.util.Objects;
/**
* Request.
*/
public class Request {
/**
* The type of this request, used by each item in the chain to see if they should or can handle
* this particular request.
*/
private final RequestType requestType;
/**
* A description of the request.
*/
private final String requestDescription;
/**
* Indicates if the request is handled or not. A request can only switch state from unhandled to
* handled, there's no way to 'unhandle' a request.
*/
private boolean handled;
/**
* Create a new request of the given type and accompanied description.
*
* @param requestType The type of request
* @param requestDescription The description of the request
*/
public Request(final RequestType requestType, final String requestDescription) {
this.requestType = Objects.requireNonNull(requestType);
this.requestDescription = Objects.requireNonNull(requestDescription);
}
/**
* Get a description of the request.
*
* @return A human readable description of the request
*/
public String getRequestDescription() {
return requestDescription;
}
/**
* Get the type of this request, used by each person in the chain of command to see if they should
* or can handle this particular request.
*
* @return The request type
*/
public RequestType getRequestType() {
return requestType;
}
/**
* Mark the request as handled.
*/
public void markHandled() {
this.handled = true;
}
/**
* Indicates if this request is handled or not.
*
* @return <tt>true</tt> when the request is handled, <tt>false</tt> if not
*/
public boolean isHandled() {
return this.handled;
}
@Override
public String toString() {
return getRequestDescription();
}
}

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/*
* 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.chain;
import lombok.AllArgsConstructor;
import lombok.extern.slf4j.Slf4j;
/**
* RequestHandler.
*/
@Slf4j
@AllArgsConstructor
public abstract class RequestHandler {
private final RequestHandler next;
/**
* Request handler.
*/
public void handleRequest(Request req) {
if (next != null) {
next.handleRequest(req);
}
}
protected void printHandling(Request req) {
LOGGER.info("{} handling request \"{}\"", this, req);
}
@Override
public abstract String toString();
}

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/*
* 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.chain;
/**
* RequestType enumeration.
*/
public enum RequestType {
DEFEND_CASTLE,
TORTURE_PRISONER,
COLLECT_TAX
}

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/*
* 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.chain;
import org.junit.jupiter.api.Test;
import static org.junit.jupiter.api.Assertions.assertDoesNotThrow;
/**
* Application test
*/
class AppTest {
/**
* Issue: Add at least one assertion to this test case.
*
* Solution: Inserted assertion to check whether the execution of the main method in {@link App}
* throws an exception.
*/
@Test
void shouldExecuteApplicationWithoutException() {
assertDoesNotThrow(() -> App.main(new String[]{}));
}
}

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/*
* 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.chain;
import static org.junit.jupiter.api.Assertions.assertTrue;
import java.util.List;
import org.junit.jupiter.api.Test;
/**
* Date: 12/6/15 - 9:29 PM
*
* @author Jeroen Meulemeester
*/
class OrcKingTest {
/**
* All possible requests
*/
private static final List<Request> REQUESTS = List.of(
new Request(RequestType.DEFEND_CASTLE, "Don't let the barbarians enter my castle!!"),
new Request(RequestType.TORTURE_PRISONER, "Don't just stand there, tickle him!"),
new Request(RequestType.COLLECT_TAX, "Don't steal, the King hates competition ...")
);
@Test
void testMakeRequest() {
final var king = new OrcKing();
REQUESTS.forEach(request -> {
king.makeRequest(request);
assertTrue(
request.isHandled(),
"Expected all requests from King to be handled, but [" + request + "] was not!"
);
});
}
}