Java - 如何防止 WindowClosing 实际关闭窗口

Question

对大多数人来说，我似乎有相反的问题。我有以下非常标准的代码来查看用户是否想在关闭窗口之前进行一些保存：

  frame.setDefaultCloseOperation(WindowConstants.DO_NOTHING_ON_CLOSE);
  frame.addWindowListener(new WindowAdapter() {
     public void windowClosing(WindowEvent ev) {
      boolean close = true;
         // check some files, asking if the user wants to save
         // YES and NO handle OK, but if the user hits Cancel on any file,
         //   I want to abort the close process     
         // So if any of them hit Cancel, I set "close" to false
      if (close) {
          frame.dispose();
          System.exit(0);
         }
       }            
});

无论我尝试什么，当我退出 windowClosing 时，窗口总是关闭。将 WindowAdapter 更改为 WindowListener 没有任何区别。奇怪的是，文档明确指出“如果程序在处理此事件时没有明确隐藏或处置窗口，则窗口关闭操作将被取消”，但它对我来说不起作用。还有其他方法可以处理框架上的 x 吗？ TIA

Answer 1

我刚刚尝试了这个最小的测试用例：

import java.awt.event.WindowAdapter;
import java.awt.event.WindowEvent;

import javax.swing.JFrame;
import javax.swing.WindowConstants;

public class Test {

    public static void main(String[] args) {
        final JFrame frame = new JFrame("Test");
        frame.setDefaultCloseOperation(WindowConstants.DO_NOTHING_ON_CLOSE);
        frame.addWindowListener(new WindowAdapter() {
            public void windowClosing(WindowEvent ev) {
                //frame.dispose();
            }
        });
        frame.setVisible(true);
    }

}

如果我保留 dispose 调用的注释并点击关闭按钮，则窗口不会退出。取消注释并点击关闭按钮，窗口关闭。

我不得不猜测您设置“关闭”变量的逻辑有问题。尝试仔细检查。

Answer 2

这是关键，我认为：frame.setDefaultCloseOperation(WindowConstants.DO_NOTHING_ON_CLOSE); 使我编写的测试用例有所不同。

Answer 3

不知道你的问题在哪里，

import javax.swing.*;
import java.awt.*;
import java.awt.event.*;

public class ClosingFrame extends JFrame {

    private JMenuBar MenuBar = new JMenuBar();
    private JFrame frame = new JFrame();
    private static final long serialVersionUID = 1L;
    private JMenu File = new JMenu("File");
    private JMenuItem Exit = new JMenuItem("Exit");

    public ClosingFrame() {
        File.add(Exit);
        MenuBar.add(File);
        Exit.addActionListener(new ExitListener());
        WindowListener exitListener = new WindowAdapter() {

            @Override
            public void windowClosing(WindowEvent e) {
                int confirm = JOptionPane.showOptionDialog(frame,
                        "Are You Sure to Close this Application?",
                        "Exit Confirmation", JOptionPane.YES_NO_OPTION,
                        JOptionPane.QUESTION_MESSAGE, null, null, null);
                if (confirm == JOptionPane.YES_OPTION) {
                    System.exit(1);
                }
            }
        };
        frame.addWindowListener(exitListener);
        frame.setDefaultCloseOperation(EXIT_ON_CLOSE);
        frame.setJMenuBar(MenuBar);
        frame.setPreferredSize(new Dimension(400, 300));
        frame.setLocation(100, 100);
        frame.pack();
        frame.setVisible(true);
    }

    private class ExitListener implements ActionListener {

        @Override
        public void actionPerformed(ActionEvent e) {
            int confirm = JOptionPane.showOptionDialog(frame,
                    "Are You Sure to Close this Application?",
                    "Exit Confirmation", JOptionPane.YES_NO_OPTION,
                    JOptionPane.QUESTION_MESSAGE, null, null, null);
            if (confirm == JOptionPane.YES_OPTION) {
                System.exit(1);
            }
        }
    }

    public static void main(String[] args) {
        SwingUtilities.invokeLater(new Runnable() {

            @Override
            public void run() {
                ClosingFrame cf = new ClosingFrame();
            }
        });
    }
}

Answer 4

对于这件事的处理：
如果用户选择是，则在该if else 的花括号内使用setDefaultCloseOperation(DISPOSE_ON_CLOSE);

如果选择取消，则使用setDefaultCloseOperation(DO_NOTHING_ON_CLOSE);

考虑例子：

int safe = JOptionPane.showConfirmDialog(null, "titleDetails!",  "title!!", JOptionPane.YES_NO_CANCEL_OPTION);

if(safe == JOptionPane.YES_OPTION){
    setDefaultCloseOperation(DISPOSE_ON_CLOSE);//yes

} else if (safe == JOptionPane.CANCEL_OPTION) {
    setDefaultCloseOperation(DO_NOTHING_ON_CLOSE);//cancel
} else {
    setDefaultCloseOperation(DISPOSE_ON_CLOSE);//no
}

Answer 5

不确定您的问题出在哪里，但这对我有用！

frame.addWindowListener(new WindowAdapter() {

            public void windowClosing(WindowEvent evt) {
                            int res=JOptionPane.showConfirmDialog(null,
                                    "Do you want to exit.?");
                            if(res==JOptionPane.YES_OPTION){
                                    Cal.this.dispose();
                            }
            }                               
        });

Answer 6

为了解决同样的问题，我尝试了本文的第一个答案。 作为单独的应用程序，它可以工作，但在我的情况下不行。 也许区别在于 JFrame（答案）和 FrameView（我的情况）。

public class MyApp extends SingleFrameApplication { // application class of my project
  ...
  protected static MyView mainForm; // main form of application
  ... 
}  
public class MyView extends FrameView {
    ...
    //Adding this listener solves the problem. 
    MyApp.getInstance().addExitListener(new ExitListener() {

      @Override
      public boolean canExit(EventObject event) {
        boolean res = false;
        int reply = JOptionPane.showConfirmDialog(null,
                "Are You sure?", "", JOptionPane.YES_NO_OPTION);
        if (reply == JOptionPane.YES_OPTION) {
          res = true;
        }
        return res;
      }
      @Override
      public void willExit(EventObject event) {
      }
    });
    ...
}   

Answer 7

setDefaultCloseOperation() 方法有助于解决问题。https://chortle.ccsu.edu/java5/Notes/chap56/ch56_9.html

查看此链接