Special Effects and Game Development in Java(TM) - The Applet AppletAnimator

import java.applet.*;

import java.awt.*;



public class appletanimator extends Applet implements Runnable {



public Thread animationthread = null;



//The Image array "images" must be global.

Image images[];



//The variable "currentimage" will hold the

//image currently being displayed.

int currentimage=0;



public void init()

{

    //Init "images" to have four elements.

    images=new Image[4];

    MediaTracker tracker=new MediaTracker(this);



    //We use a for-loop to load the images.

    for (int i=0; i<4; i++)

    {

        //"image0.gif","image1.gif",...,"image3.gif" will be

        //loaded.

        images[i]=getImage(getDocumentBase(),"image"+i+".gif");



        //The ID for each image must be increased

        //for each image that is added to the

        //tracker.

        tracker.addImage(images[i],i);

    }

    //Finally we must make sure the tracker loads the images.

    try {tracker.waitForAll();}

    catch(InterruptedException e)

    {

        System.out.println("Something happened while reading images...");

    }

}



public void start()

{

    if (animationthread == null)

    {

         animationthread = new Thread(this,"animationthread");

         animationthread.start();

    }

}



public void stop()

{

    if ((animationthread != null) && animationthread.isAlive())

        animationthread.stop();

    animationthread = null;

}



public synchronized void paint(Graphics g)

{

    //The integer "currentimage" is used as

    //index for the "images" array.

    g.drawImage(images[currentimage],0,0,this);

}



public void update(Graphics g)

{

    paint(g);

}



public void run()

{

    while (true)

    {

        update(getGraphics());



        //"currentimage" is increased so that the next

        //image is displayed in the next screen update.

        currentimage++;



        //However, "currentimage" must not exceed the

        //index value of 3.

        if (currentimage>3) currentimage=0;

        try {Thread.sleep(200);}

        catch(InterruptedException e) {}

    }

}



}