GofPatterns Gofpatterns





Behavioral Patterns  «Prev 

Chain of Responsibility Code in Java

Chain.java: This is the interface that acts as a chain link.
package com.java.behavioral.chainofresponsibility;
public interface Chain {
 public abstract void setNext(Chain nextInChain);
 public abstract void process(Number request);
}
Number.java: This class represents the request object.

package com.java.behavioral.chainofresponsibility;
public class Number {
 private int number;
 public Number(int number) {
  this.number = number;
 }
 public int getNumber() {
  return number;
 }
}

NegativeProcessor.java: This class acts as the link in the chain series.

package com.java.behavioral.chainofresponsibility;
public class NegativeProcessor implements Chain {
 private Chain nextInChain;
 public void setNext(Chain c) {
  nextInChain = c;
 }
 public void process(Number request) {
  if(request.getNumber() < 0) {
   System.out.println("NegativeProcessor : " + request.getNumber());
  } else {
    nextInChain.process(request);
  }
 }
}


ZeroProcessor.java: This class is another link in the chain series.

package com.java.behavioral.chainofresponsibility;

public class ZeroProcessor implements Chain {
 private Chain nextInChain;
 public void setNext(Chain c) {
  nextInChain = c;
 }
 public void process(Number request) {
  if (request.getNumber() == 0) {
   System.out.println("ZeroProcessor : " + request.getNumber());
  } else{
   nextInChain.process(request);
  }
 }
}

PositiveProcessor.java: This class represents another link in the chain series.

package com.java.behavioral.chainofresponsibility;
public class PositiveProcessor implements Chain {
 private Chain nextInChain;
 public void setNext(Chain c) {
  nextInChain = c;
 }
 public void process(Number request) {
  if(request.getNumber() > 0) {
   System.out.println("PositiveProcessor : " + request.getNumber());
	}else {
   nextInChain.process(request);
	}
 }
}

TestChain.java: This class configures the chain of responsibility and executes it.

package com.java.behavioral.chainofresponsibility;
public class TestChain {
 public static void main(String[] args) {
  //configure Chain of Responsibility
  Chain c1 = new NegativeProcessor();
  Chain c2 = new ZeroProcessor();
  Chain c3 = new PositiveProcessor();
  c1.setNext(c2);
  c2.setNext(c3);
  //calling chain of responsibility
  c1.process(new Number(99));
  c1.process(new Number(-30));
  c1.process(new Number(0));
  c1.process(new Number(100));
 }
}