Accessing Surrounding Variables

• Methods of inner classes can access variables that are defined in surrounding scope
• Useful when implementing event handlers
• Example: Animation
  Ten times per second, we will move a shape to a different position

  class Mover implements ActionListener
  {
     public void actionPerformed(ActionEvent event)
     {
        // Move the rectangle
     }
  }
  
  ActionListener listener = new Mover();
  final int DELAY = 100; // Milliseconds between timer ticks
  Timer t = new Timer(DELAY, listener);
  t.start();