关于java JFrame 中如何解决关闭showConfirmDialog对话框,而此对话框关闭但主窗体不关闭的问题?

 1 package Test;
 2 
 3 import java.awt.event.WindowAdapter;
 4 import java.awt.event.WindowEvent;
 5 import javax.swing.JFrame;
 6 import javax.swing.JOptionPane;
 7 
 8 public class Demo {
 9     private JFrame frame;
10 
11     public static void main(String[] args) {
12         Demo window = new Demo();
13         window.frame.addWindowListener(new WindowAdapter() {
14             public void windowClosing(WindowEvent e) {                
15                 int i= JOptionPane.showConfirmDialog(null, "确认退出吗？");
16                 if(i==JOptionPane.OK_OPTION){
17                     System.exit(0);                    
18                 }else{
19                     
20                 }
21             }
22         });
23     }
24 
25     public Demo() {
26         initialize();
27     }
28 
29     private void initialize() {
30         frame = new JFrame();
31         frame.setBounds(100, 100, 450, 300);
32         // frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);//默认点击关闭
33         frame.setVisible(true);
34         frame.setDefaultCloseOperation(JFrame.DO_NOTHING_ON_CLOSE);
35     }
36 }