A beginner trying to create platform game

Question

I'm a new programmer and just learning Java from the dummies books... I'm trying to make this Java platform game applet that I guess plays like Megaman/Mario/Castlevania.
Hmm my question would be that my applet slows down a lot on browsers, and I would like to learn how to double buffer as I've seen people suggest on this forum.
Also I would like to know why the sound doesn't seem to work on 99% of the people who try it.
You can check the game here: http://www.info.com.ph/~arivera/game/testmain.html
And the source code is here: http://www.info.com.ph/~arivera/game/source
Please give suggestions... my code is still very messy and unoptimized too, please bear with me.
(Updates may occur on the game itself while I work on it.)

Answer 1

There's two things you'll want to think about implementing in your applet - active rendering and double buffering as you mentioned.
Active rendering consists of drawing to the screen in the same thread that runs the game applet. By default, when you call repaint(), the AWT Event thread handles the repainting and gets around to repainting the screen whenever it feels like doing so - sometimes not at all! (well, that's not entirely true, but you get the idea)
Double buffering entails writing to an offscreen buffer, and then drawing that buffer to the screen.
Thankfully, both are relatively easy to implement.
Active rendering is the easier of the two to implement. In your game loop, where you call repaint(), don't! Instead, call paint() directly and use the applets getGraphics() method, which will return a Graphics or Graphics2D object for you to use. So instead of having repaint(), replace it with paint(getGraphics());
Double buffering is a bit more complicated to implement. I'd suggest trying this after you've tried active rendering. Double buffering includes have an Image field in your applet class. I often call it 'buffer', but there's quite a few other common names you'll come across for it.
To initialize the image, call the applet's createImage(width, height) method. This will return an Image object. You can get a Graphics object that corresponds to that image by calling its getGraphics() method just like you do with active rendering. You no longer want to have all of the painting being done in the paint() method of your applet. Instead, a new method is in order to handle the painting of the game screen to the buffer. Your paint method then should simply call g.drawImage(...) and draw the backbuffer to the screen.
A small example:
public class doubleBufferApplet implements Applet
Image buffer;
. . . //Other fields
public void init()
buffer = createImage(getWidth(), getHeight()); //returns an Image object the size of the applet and assigns it to buffer
. . . //Do other initializing
public void run()
while(gameIsStillRunning) //Main game loop
. . . //Run through and update the game
if(buffer != null)
drawGame(buffer.getGraphics()) //Draw the game to the backbuffer
paint(getGraphics()); //Draw the backbuffer to the screen
public void drawGame(Graphics g)
. . . //Do your painting here
public void paint(Graphics g)
if(buffer != null)
g.drawImage(buffer, 0, 0, this);
public void update(Graphics g) //Override the default update() method to avoid Java from calling it randomly
paint(g);
I hope that gave you a decent idea of how to go about implementaing active rendering and a buffer. If not, I'll try harder to answer any questions you have (or some of the more experienced users around here will help you out as well I'm sure).