java - 为什么用ConfirmDialog关闭Frme窗口会在两种情况下(确定和取消)关闭？

Question

这是我的代码:

            addWindowListener(new WindowAdapter() {

            @Override
            public void windowClosing(WindowEvent e) {
               int a = JOptionPane.showConfirmDialog(null, 
                            "Are you sure you want to exit the program?", "Exit Program ",
                            JOptionPane.YES_NO_OPTION);
               System.out.println(a);
               if(a==JOptionPane.OK_OPTION){
                   dispose();
               }
           }});

问题是 a==OK_OPTION 或 a==CANCEL_OPTION 框架将关闭。

为什么？

Answer 1

您可能已将 JFrame 的默认关闭操作设置为 EXIT_ON_CLOSE。因此，无论您按 OK 还是 CANCEL，都会退出 JFrame。如果您想手动处理 JFrame 的关闭操作，则应将默认关闭操作设置为 DO_NOTHING_ON_CLOSE。

setDefaultCloseOperation(JFrame.DO_NOTHING_ON_CLOSE);
addWindowListener(new WindowAdapter() {
            @Override
            public void windowClosing(WindowEvent e) {
               int a = JOptionPane.showConfirmDialog(null, 
                            "Are you sure you want to exit the program?", "Exit Program ",
                            JOptionPane.YES_NO_OPTION);
               System.out.println(a);
               if(a==JOptionPane.OK_OPTION){
                   dispose();//You can use System.exit(0) if you want to exit the JVM
               }
           }});