Decorator Pattern

Attaches additional responsibilities to an object dynamically. Decorators provides a flexible alternative to subclassing for extending functionality.

http://javapapers.com/design-patterns/decorator-pattern/

(abstract class) compontent{

m1();

m2();

}

concreteComponent{

m1();

m2();

}

(abstract) Decorator extends component{

m1();

m2();

}

you can use the decorator to decorate concreteComponent to concreteNewComponent with something additional

Design pattern book 95~98

Beverage beverage = new Espresso();

Beverage beverage2 = new DarkRoast();

beverage2 = new Mocha(beverage2);

beverage2 = new Mocha(beverage2); // double mocha

beverage2 = new Whip(beverage2); // with whip cream