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

import java.applet.*;

import java.awt.*;



public class appletanimator2 extends Applet implements Runnable {



public Thread animationthread = null;



//"maxitems" will be used to indicate the number of

//images that exist.

int maxitems=0;



//"sleeptime" indicates the delay between each image

//in milliseconds.

int sleeptime=0;

Image images[];

int currentimage=0;



public void init()

{

    //Get the value of the parameter "maxitems"

    //with the number base 10.

    maxitems=getIntegerParameter("maxitems",10);



    //Get the value of the parameter "sleeptime".

    sleeptime=getIntegerParameter("sleeptime",10);



    //The array "images" will have "maxitems" number

    //of elements.

    images=new Image[maxitems];

    MediaTracker tracker=new MediaTracker(this);    

    for (int i=0; i<maxitems; i++)
    {
        //The following line will read the values of the
        //parameters "image0", "image1", "image2" and so on
        //up to the value that maxitems indicates. It will also
        //use the strings to load the files specified in those
        //parameters.
        images[i]=getImage(getDocumentBase()
            ,getParameter("image"+i));



        //The ID number for each image must be increased

        //for each image you add to the tracker.

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

    }

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

    try {tracker.waitForAll();}

    catch(InterruptedException e)

    {

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

    }

}



public int getIntegerParameter(String name, int base)

{

    String value=getParameter(name);

    int intvalue;

    try {intvalue=Integer.parseInt(value,base);}

    catch (NumberFormatException e) {return 0;}

    return intvalue;

}



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 it must not exceed the value

        //of maxitems minus 1.

        if (currentimage>maxitems-1) currentimage=0;



        //The variable sleeptime sets

        //the delay in milliseconds.

        try {Thread.sleep(sleeptime);}

        catch(InterruptedException e) {}

    }

}



}