interface Dosa

{

 public String makeDosa();

}

​

class PlainDosa implements Dosa

{

 @Override

 public String makeDosa()

 {

 return "Plain Dosa";

 }

}

​

abstract class DosaDecorator implements Dosa

{

 protected Dosa dosa;

 public DosaDecorator( Dosa dosa )

 {

 this.dosa = dosa;

 }

 public String makeDosa()

 {

 return dosa.makeDosa();

 }

}

​

class MasalaDosa extends DosaDecorator

{

 public MasalaDosa( Dosa dosa )

 {

 super(dosa);

 }

 public String makeDosa()

 {

 return dosa.makeDosa() + addMasala();

 }

 private String addMasala()

 {

 return ",Masala added";

 }

}

​

class OnionDosa extends DosaDecorator

{

 public OnionDosa( Dosa dosa )

 {

 super(dosa);

 }

 public String makeDosa()

 {

 return dosa.makeDosa() + addOnion();

 }

 private String addOnion()

 {

 return ",Onion added";

 }

}

​

class MysoreDosa extends DosaDecorator

{

 public MysoreDosa( Dosa dosa )

 {

 super(dosa);

 }

 public String makeDosa()

 {

 return dosa.makeDosa() + addMysoreMasala();

 }

 private String addMysoreMasala()

 {

 return ",Mysore Masala added";

 }

}

​

​

public class DecoratorDesignPattern {

     public static void main( String args[] )

     {

     PlainDosa plainDosaObj = new PlainDosa();

     String plainDosa = plainDosaObj.makeDosa();

     System.out.println(plainDosa);

     String onionDosa = new OnionDosa(plainDosaObj).makeDosa();

     System.out.println("\n'" + onionDosa + "' using OnionDosa");

     String masalaDosa = new MasalaDosa(plainDosaObj).makeDosa();

     System.out.println("\n'" + masalaDosa + "' using MasalaDosa");

     String mysoreDosa = new MysoreDosa(plainDosaObj).makeDosa();

     System.out.println("\n'" + mysoreDosa + "' using MysoreDosa");

     }

}

​