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Design Patterns in Java (Behavioral) - Chain of Responsability

Chain of Responsibility

  • Decoupling sender from receiver
  • Promote loose coupling


Example


This example pass a request to be approved and validate if that position can approve it or need to be passed to the next level.

Main














 public static void main(String[] args) {



  



  Manager m = new Manager();



  Director d = new Director();



  CEO c = new CEO();



  



  m.setSuccesor(d);



  d.setSuccesor(c);



  



  Request r1 = new Request(1, 500);



  m.handleRequest(r1);



  



  



  Request r2 = new Request(2, 500);



  m.handleRequest(r2);



  






























 }

Handle














public abstract class Handler {







 protected Handler succesor;



 



 public void setSuccesor(Handler succesor){



  this.succesor = succesor;



 }



 



 public abstract void handleRequest(Request r);







}

Request
















public class Request {







 private int requestType;



 private int amount;



 



 public Request(int requestType, int amount){



  this.requestType = requestType;



  this.amount = amount;



 }



 



 public int getRequestType() {



  return requestType;



 }



 public double getAmount() {



  return amount;



 }



 



 
































}

Manager
















public class Manager extends Handler {







 @Override



 public void handleRequest(Request r) {



  if(r.getRequestType() == 3){



   System.out.println(" Manager can approve this request");



  }else{



   succesor.handleRequest(r);



  }







 }






























}

Director

















public class Director extends Handler {







 @Override



 public void handleRequest(Request r) {



  if(r.getRequestType() == 2){



   System.out.println(" Director can approve this request");



  }else{



   succesor.handleRequest(r);



  }



  



 } 




























}

CEO


















public class CEO extends Handler {







 @Override



 public void handleRequest(Request r) {



  System.out.println("CEO can approve everything");







 }






















}








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