song.java

designpatterns for aop

package designpatterns.observer.java;

import java.util.*;


public class Song implements Playable, Subject{
	private String name;

	public Song(String name) {
		super();
		this.name = name;
	}
	
	public String getName() {
		return name;
	}

	public void play() {
		System.out.println("Playing song " + getName());
		notifyObservers();
	}
	
	public void showLyrics(){
		System.out.println("Displaying lyrics for " + getName());
		notifyObservers();
	}
	
	public boolean equals(Object o){
		Song other = (Song) o;
		return this.name.equals(other.name);
	}
	
	public int hashCode() {
		return name.hashCode();
	}
	
	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);
		}
	}
}