Swing II - Absolute Java - page 1022

Display 18.2 A Window Listener (part 2 of 3)

44 setLayout( new BorderLayout());
45 JLabel confirmLabel = new JLabel(
46 "Are you sure you want to exit?");
47 add(confirmLabel, BorderLayout.CENTER);

48 JPanel buttonPanel = new JPanel();
49 buttonPanel.setBackground(Color.ORANGE);
50 buttonPanel.setLayout( new FlowLayout());

51 JButton exitButton = new JButton("Yes");
52 exitButton.addActionListener( this );
53 buttonPanel.add(exitButton);

54 JButton cancelButton = new JButton("No");
55 cancelButton.addActionListener( this );
56 buttonPanel.add(cancelButton);
57 add(buttonPanel, BorderLayout.SOUTH);
58 }
59 public void actionPerformed(ActionEvent e)
60 {
61 String actionCommand = e.getActionCommand();

62 if (actionCommand.equals("Yes"))
63 System.exit(0);
64 else if (actionCommand.equals("No"))
65 dispose(); //Destroys only the ConfirmWindow .
66 else
67 System.out.println(
"Unexpected Error in Confirm Window.");
68 }
69 } //End of inner class ConfirmWindow
70
71 public static void main(String[] args)
72 {
73 WindowListenerDemo demoWindow = new WindowListenerDemo();
74 demoWindow.setVisible( true );
75 }
76
77 public WindowListenerDemo()
78 {
79 setSize(WIDTH, HEIGHT);
80 setTitle("Window Listener Demonstration");
81
82 setDefaultCloseOperation(JFrame.DO_NOTHING_ON_CLOSE);
83 addWindowListener( new CheckOnExit());
84
85 getContentPane().setBackground(Color.LIGHT_GRAY);
86 JLabel aLabel = new JLabel(
"I like to be sure you are sincere.");
87 add(aLabel);
88 }
89 }

Even if you have a window listener,
you normally must still invoke
setDefaultCloseOperation.