To play a sound from a JAR file (the .AU file in the JAR must be accessible via the CLASSPATH of course!) :

 import java.io.*;
import java.net.*;

import sun.audio.*;

public class AppAudio {
  public static void main(String args[]) throws Throwable {
    InputStream in = AppAudio.class.getResourceAsStream(args[0]);
    AudioStream as = new AudioStream(in);
    AudioPlayer.player.start(as);
    Thread.sleep(5000);
  }
}