Decorator in Java

public class DecoratorAfter {

 

interface I { void doIt(); }

 

static class A implements I { public void doIt() { System.out.print( 'A' ); } }

 

static abstract class D implements I {

   private I core;

   public D( I inner ) { core = inner; }

   public void doIt()  { core.doIt();  }

}

 

static class X extends D {

   public X( I inner ) { super( inner ); }

   public void doIt()  {

      super.doIt();

      doX();

   }

   private void doX() { System.out.print( 'X' ); }

}

 

static class Y extends D {

   public Y( I inner ) { super( inner ); }

   public void doIt()  {

      super.doIt();

      doY();

   }

   private void doY() { System.out.print( 'Y' ); }

}

 

static class Z extends D {

   public Z( I inner ) { super( inner ); }

   public void doIt()  {

      super.doIt();

      doZ();

   }

   private void doZ() { System.out.print( 'Z' ); }

}

 

public static void main( String[] args ) {

   I[] array = { new X( new A() ), new Y( new X( new A() ) ),

                 new Z( new Y( new X( new A() ) ) ) };

   for (int i=0; i < array.length; i++) {

      array[i].doIt();

      System.out.print( "  " );

}  }  }