Applet Freezes

Question

When I run my applet it freezes, can anyone see what's wrong?
public void paint(Graphics g)
  g.drawImage(airplane, planesXPos, planesYPos, PLANE_WIDTH,                                 PLANE_HEIGHT, this);
  g.drawString(numbers, textXPos, textYPos);
  planesXPos--;
  textXPos--;
public void actionPerformed(ActionEvent event)
  level = new Level();  
  if (event.getSource() == easy)
   level.setToEasy();
  else if (event.getSource() == medium)
   level.setToMedium();
  else
   level.setToHard();
  runGame();
  // True if the screen is clear, false otherwise.
public boolean isScreenClear()
  boolean flag = false;    
  if (textXPos < 0)
   flag = true;
  return flag;
public void runGame()
  number.ammendString();
  numbers = number.getAllNumbers();
  while (! isScreenClear())
   repaint();
}Thank You

Answer 1

Why isn't updating state good and why isn't it
working?Updating state is good. Updating state in your paint method is bad, because (1) you don't necessarily have control over when paint() is invoked, and (2) it's an operation about viewing and things like that shouldn't have side-effects. By "updating state", I'm referring to these lines:  planesXPos--;
  textXPos--; if I wasn't clear.
Also, the game will pause, once textPos is < 0. that
is when I want it to stop repainting.That's not what I meant. Think about how animation works. An image is displayed, held for a bit, then replaced with another image which has been updated slightly, which is then held for a bit, etc. Consider movies. A movie runs at 24 frames per second, so since each individual frame is a separate drawing (in practice, animated movies often "shoot twos" which means 12 fps; sometimes they "shoot fours", etc.) then each drawing is held up for 1/24 of a second.
Your code isn't doing that, so the only time delimiter between frames is the implicit one controlled by redraws updating state. The results are unpredictable and probably won't look good.
A more typical animation/game loop looks more like this (in psuedo-code):
while (should_continue_to_animate) {
  update_state();
  repaint();
  sleep();  // Thread.sleep() or using a Timer
}There are other variations, but we'll worry about those later...