Killer Game Programming in Java

The Sound Player

SoundPlayer.java (located in SoundExamps/SoundPlayer/) shows off the capabilities of the AudioClip class (see Figure 7-1) in a longer example.

Figure 7-1. The SoundPlayer application

A selection of sound files in different formats (all located in the Sounds/ subdirectory below SoundPlayer/) are offered up. They can be played once, looped, or stopped. It's possible to have multiple clips playing and looping simultaneously, and the stop button terminates all the currently playing clips. This example is somewhat similar to the Java Sound tutorial example, SoundApplication.

Figure 7-2 gives the class diagram for SoundPlayer, showing all the public and private methods and variables in the class.

Two important data structures are in play here:

    private HashMap soundsMap;
    private ArrayList playingClips;

soundsMap holds the loaded AudioClips, indexed by their filenames. playingClips maintains a list of currently playing AudioClips (or, to be more precise, what I think is playing).

Figure 7-2. Class diagram for SoundPlayer

loadSounds() loads the AudioClips and stores them in soundsMap for later use:

    private void loadSounds()
    {
      soundsMap = new HashMap();
      for (int i=0; i < soundFNms.length; i++) {
        AudioClip clip = Applet.newAudioClip( getClass().getResource(SOUND_DIR + soundFNms[i]) ...