java 中播放音乐的问题

//我用的是Eclipse，在里面播放音乐，运行就不行了。歌曲和代码放在一起。
我用java Applet运行正确，但还是没有声音。
用 java Bean 就会出错。
错误如下：
/*IWAV0054I Applet Playsound1 started
Exception in thread "AWT-EventQueue-0" java.lang.NullPointerException
at Playsound1.actionPerformed(Playsound1.java:43)
at java.awt.Button.processActionEvent(Button.java:392)
at java.awt.Button.processEvent(Button.java:360)
at java.awt.Component.dispatchEventImpl(Component.java:4413)
at java.awt.Component.dispatchEvent(Component.java:4243)
at java.awt.EventQueue.dispatchEvent(EventQueue.java:599)
at java.awt.EventDispatchThread.pumpOneEventForFilters(EventDispatchThread.java:273)
at java.awt.EventDispatchThread.pumpEventsForFilter(EventDispatchThread.java:183)
at java.awt.EventDispatchThread.pumpEventsForHierarchy(EventDispatchThread.java:173)
at java.awt.EventDispatchThread.pumpEvents(EventDispatchThread.java:168)
at java.awt.EventDispatchThread.pumpEvents(EventDispatchThread.java:160)
at java.awt.EventDispatchThread.run(EventDispatchThread.java:121)*/import java.applet.Applet;
import java.applet.AudioClip;
import java.awt.Button;
import java.awt.Choice;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import java.awt.event.ItemEvent;
import java.awt.event.ItemListener;
public class Playsound1 extends Applet implements ItemListener,ActionListener{
 AudioClip mysound;
Choice select_sound=new Choice();
Button paly=new Button("play");
Button loop=new Button("loop");
Button stop=new Button("stop");
public void init(){
select_sound.addItem("sound1.wav");
select_sound.addItem("sound2.wav");
select_sound.addItem("sound3.wav");
add(select_sound);
add(paly);
add(loop);
add(stop);
select_sound.addItemListener(this);
paly.addActionListener(this);
loop.addActionListener(this);
stop.addActionListener(this);
} public void itemStateChanged(ItemEvent e) {
// TODO 自动生成方法存根
mysound=getAudioClip(getCodeBase(),select_sound.getSelectedItem());
} public void actionPerformed(ActionEvent e) {
// TODO 自动生成方法存根
if(e.getSource()==paly)
mysound.play();
else
if(e.getSource()==loop)
mysound.loop();
else
if(e.getSource()==stop)
mysound.stop();
}}
是不是还要安装什么插件，