package Bean; import Interface.Quackable; /** * Created by Administrator on 2017/7/14. */ public class RedheadDuck implements Quackable { public RedheadDuck() { observable = new Observable(this); } @Override public void quack() { System.out.println("Quack"); notifyObservers(); } Observable observable; public void registerObserver(Interface.Observer observer) { observable.registerObserver(observer); } @Override public void notifyObservers() { observable.notifyObservers(); } }