Decorator Pattern implementation in java tutorial or example

What is Decorator Patter?

It changes(extends or modify) the behavior of an instance at run time.

When to use Decorator Pattern:

We can choose any single object of a class and modify its behaviour leaving the other instances unmodified.Inheritance adds functionality to classes whereas the decorator pattern adds functionality to objects in other objects.

Implementation:

/**
 * @author Abhinaw.Tripathi
 *
 */
interface House
{
  public String makeHouse();
}

class SimpleHouse implements House
{

@Override
public String makeHouse() {
// TODO Auto-generated method stub
return "Base House";
}

}

abstract class HouseDecorator implements House
{
protected House house;

public HouseDecorator(House h)
{
this.house=h;
}
public String makeHouse()
{
return house.makeHouse();
}
}

class ColorDecorator extends HouseDecorator
{

public ColorDecorator(House h) {
super(h);
// TODO Auto-generated constructor stub
}

private String addColors()
{

return "+colors";
}
public String makeHouse()
{
return house.makeHouse() + addColors() ;
}

}

public class DecoratorPatternTest {

/**
*
*/
public DecoratorPatternTest() {
// TODO Auto-generated constructor stub
}

/**
* @param args
*/
public static void main(String[] args) {
// TODO Auto-generated method stub

House house =new ColorDecorator(new ColorDecorator(new SimpleHouse())) ;
System.out.println(house.makeHouse());
}


}