Chain of Responsibility Pattern modified

Java

by techbard 2016. 7. 21. 14:11

# Handler.java

import java.util.ArrayList;

public abstract class Handler {
Handler nextHandler;

protected void setNextHandler(Handler handler) {
this.nextHandler = handler;
}

protected void setNextHandlers(ArrayList<Handler> handlers) {
for (int i = 0; i < handlers.size() - 1; i++) {
handlers.get(i).setNextHandler(handlers.get(i + 1));
}
}

abstract void checkRequest(Request request);
}

# Request.java

public class Request {
private int requestValue = 0;

public int getRequestValue() {
if (this.requestValue < 0) {
this.requestValue = -this.requestValue;
}
return this.requestValue;
}

public void setRequestValue(int requestValue) {
this.requestValue = requestValue;
}
}

# CheckEven.java

public class CheckEven extends Handler {

@Override
void checkRequest(Request request) {
int requested = request.getRequestValue();

if (requested > 0 && requested % 2 == 0) {
System.out.println("[" + requested + "] is even");
} else {
nextHandler.checkRequest(request);
}
}
}

# CheckOdd.java

public class CheckOdd extends Handler {

@Override
void checkRequest(Request request) {
int requested = request.getRequestValue();

if (requested > 0 && requested % 2 != 0) {
System.out.println("[" + requested + "] is odd");
} else {
nextHandler.checkRequest(request);
}
}
}

# CheckZero.java

public class CheckZero extends Handler {

@Override
void checkRequest(Request request) {
int requested = request.getRequestValue();

if (requested == 0) {
System.out.println("[" + requested + "] is zero");
} else {
nextHandler.checkRequest(request);
}
}
}

# Main.java

import java.util.ArrayList;

public class Main {

public static void main(String[] args) {
Request request = new Request();

CheckEven checkEven = new CheckEven();
CheckOdd checkOdd = new CheckOdd();
CheckZero checkZero = new CheckZero();

ArrayList<Handler> handlers = new ArrayList<>();
handlers.add(checkEven);
handlers.add(checkOdd);
handlers.add(checkZero);

handlers.get(0).setNextHandlers(handlers);
handlers.get(0).checkRequest(request);

request.setRequestValue(-21);
handlers.get(0).checkRequest(request);

request.setRequestValue(-2);
handlers.get(0).checkRequest(request);
}
}