13. A4 Setting the Window Close Box

• The system exit procedure is not called automatically when a user clicks on the close box X.

• To enable expected behavior,

  1. Add a WindowListener to the frame.

  2. Catch the WindowClosing event.

• This can be done most effectively by subclassing the WindowAdapter class as follows:

  
          JFrame frame = new JFrame("JFrame is me");
          frame.addWindowListener(new java.awt.event.WindowAdapter()
          {
              public void windowClosing(java.awt.event.WindowEvent ev)
              { System.exit(0); }
          }
          );
  
  

• See next side for complete example.