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());
}
}