Змейка на джаве

/*
 * The number of times to update the game per second.
 */
private static final int UPDATES_PER_SECOND = 10;
 
/**
 * Responsible for setting up and retrieving the rendering context, then maintaining
 * the game loop.
 */
public void startGame() {
 /*
  * Create the buffers and get the graphics.
  */
 canvas.createBufferStrategy(2);
  
 /*
  * Grab a reference to the graphics object.
  */
 Graphics2D g = (Graphics2D)canvas.getBufferStrategy().getDrawGraphics();
  
 /*
  * Create the variables that keep the loop executing at a constant framerate.
  */
 long start = 0L;
 long sleepDuration = 0L;
 
 /*
  * The game loop will continue to click until the program ends.
  */
 while(true) {
 
  /*
   * Set the time that the loop started.
   */
  start = System.currentTimeMillis();
  
  /*
   * Update the game.
   */
  update();
   
  /*
   * Draw the game onto the graphics object.
   */
  render(g);
  
  /*
   * Display the graphics onto the screen.
   */
  canvas.getBufferStrategy().show();
 
  /*
   * Clear the screen so we draw a fresh frame next time.
   */
   g.clearRect(0, 0, canvas.getWidth(), canvas.getHeight());
   
  /*
   * Set the time that the loop finished.
   */
  sleepDuration = (1000L / UPDATES_PER_SECOND) - (System.currentTimeMillis() - start);
   
  /*
   * If the sleep duration is greater than 0 milliseconds, attempt to sleep.
   */
  if(sleepDuration > 0) {
   try {
    Thread.sleep(sleepDuration);
   } catch(Exception e) {
    e.printStackTrace();
   }
  }
 }
}
 
/*
 * Update the game's logic.
 */
private void update() {
 //Empty for now, we'll fill this in later.
}
 
/*
 * Draw the game onto the graphics object.
 */
private void render(Graphics2D g) {
 //Empty for now, we'll fill this in later.
}