Why doesn't my square move...

Question

can someone help me find why my square doesn't move down the page?
import java.applet.*;
import java.awt.*;
public class ShapeTest extends Applet implements Runnable
Dimension bgWidthHeight;
Image buffImage;
Graphics buffGraphics;
Thread firstThread;
int h;
int w;
public void start()
if(firstThread == null)
firstThread = new Thread(this);
firstThread.start();
public void stop()
if(firstThread != null)
firstThread.stop();
firstThread = null;
public void update(Graphics g)
paint(g);
public void run()
h = bgWidthHeight.height;
w = bgWidthHeight.width;
try
while(Thread.currentThread() == firstThread)
h++;
w++;
repaint();
Thread.sleep(50);
catch(InterruptedException e) {}
public void paint(Graphics g)
bgWidthHeight = getSize();
buffImage = createImage(bgWidthHeight.width, bgWidthHeight.height);
buffGraphics = buffImage.getGraphics();
buffGraphics.fillRect(h, w, 20, 30);
g.drawImage(buffImage, 0, 0, this);
public void destroy()
buffGraphics.dispose();
}

Answer 1

Try this:
import java.applet.*;
import java.awt.*;
public class ShapeTest extends Applet implements Runnable
     Dimension bgWidthHeight;
     Image     buffImage = null;
     Graphics  buffGraphics;
     Thread    firstThread;
     int h,w;
     int x,y;
public void start()
     if (firstThread == null) firstThread = new Thread(this);
     firstThread.start();
public void stop()
     if (firstThread != null) firstThread.stop();
    firstThread = null;
public void update(Graphics g)
     paint(g);
public void run()
     h = bgWidthHeight.height;
     w = bgWidthHeight.width;
     x = 10;
     y = 10;
     while (Thread.currentThread() == firstThread)
          try
          {     repaint(x,y,20,30);
               x++;
               y++;
               repaint(x,y,20,30);
               Thread.sleep(50);
          catch(InterruptedException e) {}
public void paint(Graphics g)
     if (buffImage == null)
          bgWidthHeight = getSize();
          buffImage     = createImage(bgWidthHeight.width, bgWidthHeight.height);
          buffGraphics  = buffImage.getGraphics();
     buffGraphics.setColor(Color.white);
     buffGraphics.fillRect(0,0,w,h);
     buffGraphics.setColor(Color.red);
     buffGraphics.fillRect(x, y, 20, 30);
     g.drawImage(buffImage, 0, 0, this);
public void destroy()
     buffGraphics.dispose();
Noah
import java.applet.*;
import java.awt.*;
public class ShapeTest extends Applet implements Runnable
     Dimension bgWidthHeight;
     Image buffImage = null;
     Graphics buffGraphics;
     Thread firstThread;
     int h,w;
     int x,y;
public void start()
     if (firstThread == null) firstThread = new Thread(this);
     firstThread.start();
public void stop()
     if (firstThread != null) firstThread.stop();
firstThread = null;
public void update(Graphics g)
     paint(g);
public void run()
     h = bgWidthHeight.height;
     w = bgWidthHeight.width;
     x = 10;
     y = 10;
     while (Thread.currentThread() == firstThread)
          try
          {     repaint(x,y,20,30);
               x++;
               y++;
               repaint(x,y,20,30);
               Thread.sleep(50);
          catch(InterruptedException e) {}
public void paint(Graphics g)
     if (buffImage == null)
          bgWidthHeight = getSize();
          buffImage = createImage(bgWidthHeight.width, bgWidthHeight.height);
          buffGraphics = buffImage.getGraphics();
     buffGraphics.setColor(Color.white);
     buffGraphics.fillRect(0,0,w,h);
     buffGraphics.setColor(Color.red);
     buffGraphics.fillRect(x, y, 20, 30);
     g.drawImage(buffImage, 0, 0, this);
public void destroy()
     buffGraphics.dispose();