watcher.java

这个文件里面包含了java设计模式的一些例子讲解

package com.javapatterns.observer.watching;

import java.util.Observable;
import java.util.Observer;

public class Watcher implements Observer
{
	public Watcher(Watched w)
    {
        w.addObserver(this);
    }

    public void update( Observable ob, Object arg)
    {
        System.out.println("Data has been changed to:  '" + ((Watched)ob).retrieveData() + "'");
    }
}