Learn Java: How-To: Adding sounds to applets

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Adding sounds to Java applets

Introduction

We all know that multimedia, used properly, can make any web site more entertaining. In this article, we'll present a brief example of a Java applet that plays a sound file when it is downloaded. The compiled applet class file is very small - only 559 bytes - and can be downloaded quickly into a user's web browser.

The SoundApplet applet

Fortunately, using sounds in Java applets is very simple. The SoundApplet.java code shown in Listing 1 shows the minimal requirements needed to play a sound file when an applet is downloaded. Notice that to make the applet easy to hide on a web page, we resized it's visible dimensions to zero pixels wide, zero pixels tall.

import java.applet.*;
public class SoundApplet extends Applet {
    public void init() {
       super.init();
       resize(0,0);
       AudioClip gong = getAudioClip(getDocumentBase(), "gong.au");
       gong.play();
    }
}

Listing 1: SoundApplet.java - a simple applet that plays the "gong.au" sound file.

Notice from this example that there are really only two steps required to play a sound in a Java applet: (1) loading the sound file into an AudioClip object, and (2) playing the sound using the play() method of the AudioClip class.

Also notice that there is no path leading to the gong.au file - this applet expects to find the gong.au file in the same directory as the class file. If instead the gong.au file was located in a sub-directory named sounds, the file would have been loaded with this statement:

AudioClip gong = getAudioClip(getDocumentBase(), "sounds/gong.au");

The SoundApplet.html HTML file

Every applet needs an HTML file to access it, so in Listing 2 we've provided the source code for a bare-bones HTML file that loads the SoundApplet applet.

<HTML>
<HEAD>
<TITLE>SoundApplet Demo</TITLE>
</HEAD>
<BODY>
<APPLET CODE="SoundApplet.class" height="0" width="0"></APPLET>
</BODY>
</HTML>

Listing 2: SoundApplet.html - a simple HTML file that loads the SoundApplet applet.

Notice in this listing that nothing special is required, other than the use of the <APPLET> tag. This tag simply gives your browser the information it needs to load the SoundApplet class file. Your browser takes care of the rest of the work.

Try the on-line demo, and download the source

If you'd like to try the on-line demo of our SoundApplet applet, click here. Of course you can also save the HTML source code once it's loaded into your browser.

Click here to view/download the SoundApplet.java source code.

Finally, click here to download the gong.au sound file. (You may want to right-click on this link, then select Save Link As ....)

Listing 1:	`SoundApplet.java` - a simple applet that plays the "`gong.au`" sound file.

Listing 2:	`SoundApplet.html` - a simple HTML file that loads the SoundApplet applet.

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