书上关闭窗口的题

1. /*
2.  * NewJFrame.java
3.  *
4.  * Created on 2008年8月23日, 下午2:52
5.  */
6. package gui;
8. import javax.swing.JOptionPane;
10. /**
11.  *
12.  * @author  Administrator
13.  */
14. public class NewJFrame extends javax.swing.JFrame {
16.     /** Creates new form NewJFrame */
17.     public NewJFrame() {
18.         initComponents();
19.     }
21.     /** This method is called from within the constructor to
22.      * initialize the form.
23.      * WARNING: Do NOT modify this code. The content of this method is
24.      * always regenerated by the Form Editor.
25.      */
26.     @SuppressWarnings("unchecked")
27.     // <editor-fold defaultstate="collapsed" desc="Generated Code">                          
28.     private void initComponents() {
30.         jTextField1 = new javax.swing.JTextField();
32.         setDefaultCloseOperation(javax.swing.WindowConstants.DO_NOTHING_ON_CLOSE);
33.         setTitle("关闭窗体测试");
34.         setResizable(false);
35.         addWindowListener(new java.awt.event.WindowAdapter() {
36.             public void windowClosing(java.awt.event.WindowEvent evt) {
37.                 formWindowClosing(evt);
38.             }
39.         });
41.         jTextField1.setHorizontalAlignment(javax.swing.JTextField.CENTER);
42.         jTextField1.setText("请点击关闭按钮");
43.         jTextField1.setAutoscrolls(false);
45.         javax.swing.GroupLayout layout = new javax.swing.GroupLayout(getContentPane());
46.         getContentPane().setLayout(layout);
47.         layout.setHorizontalGroup(
48.             layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
49.             .addGroup(javax.swing.GroupLayout.Alignment.TRAILING, layout.createSequentialGroup()
50.                 .addContainerGap(125, Short.MAX_VALUE)
51.                 .addComponent(jTextField1, javax.swing.GroupLayout.PREFERRED_SIZE, 145, javax.swing.GroupLayout.PREFERRED_SIZE)
52.                 .addGap(122, 122, 122))
53.         );
54.         layout.setVerticalGroup(
55.             layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
56.             .addGroup(javax.swing.GroupLayout.Alignment.TRAILING, layout.createSequentialGroup()
57.                 .addContainerGap(113, Short.MAX_VALUE)
58.                 .addComponent(jTextField1, javax.swing.GroupLayout.PREFERRED_SIZE, 40, javax.swing.GroupLayout.PREFERRED_SIZE)
59.                 .addGap(113, 113, 113))
60.         );
62.         pack();
63.         java.awt.Dimension screenSize = java.awt.Toolkit.getDefaultToolkit().getScreenSize();
64.         java.awt.Dimension dialogSize = getSize();
65.         setLocation((screenSize.width-dialogSize.width)/2,(screenSize.height-dialogSize.height)/2);
66.     }// </editor-fold>                        
67. private void formWindowClosing(java.awt.event.WindowEvent evt) {                                   
68.             if (JOptionPane.showConfirmDialog(this, "真的要关闭吗？", "请确认", JOptionPane.OK_CANCEL_OPTION) == JOptionPane.OK_OPTION) {
69.                 System.exit(0);
70.             }
72. }                                  
74.     /**
75.      * @param args the command line arguments
76.      */
77.     public static void main(String args[]) {
78.         java.awt.EventQueue.invokeLater(new Runnable() {
80.             public void run() {
81.                 new NewJFrame().setVisible(true);
82.             }
83.         });
84.     }
86.     // Variables declaration - do not modify                     
87.     private javax.swing.JTextField jTextField1;
88.     // End of variables declaration                   
89. }