playlist.java

来自「designpatterns for aop」· Java 代码 · 共 54 行

package designpatterns.observer.java;

import java.util.*;
import java.util.ArrayList;
import java.util.Iterator;
import java.util.List;


public class Playlist implements Playable, Subject {

	private String name;
	private List songs = new ArrayList();
	
	public Playlist(String name) {
		super();
		this.name = name;
	}

	public void setSongs(List songs) {
		this.songs = songs;
	}
	
	public void play() {
		System.out.println("playing playlist " + getName());
		for (Iterator iter = songs.iterator(); iter.hasNext();) {
			Song song = (Song) iter.next();
			song.play();
		}
		notifyObservers();
	}

	public String getName() {
		return name;
	}

	private Set observers = new HashSet();
	
	public void addObserver(Observer o) {
		observers.add(o);
	}

	public void removeObserver(Observer o) {
		observers.remove(o);
	}

	public void notifyObservers() {
		for (Iterator iter = observers.iterator(); iter.hasNext();) {
			Observer o = (Observer) iter.next();
			o.update(this);
		}
	}
}