弹出JFrame关闭按钮

Question

我正在做一些基本的Java Swing application(初学者水平)。我要做的是当我按下close button on JFrame关闭窗口时，我想要一个JOptionPane Confirm Dialog而不是直接关闭

下面是JFrame 的代码

   JFrame  frame= new JFrame("frame"); 
   frame.setSize(300,300);
   frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
   frame.setVisible(true);
   frame.pack();

和JOptionPane的代码是这样的

   final JOptionPane optionPane = new JOptionPane("Are You sure?",JOptionPane.QUESTION_MESSAGE,
JOptionPane.YES_NO_OPTION);

所以当JFrame上的Close按钮被按下时这个弹出窗口应该会出现而不是直接关闭
请指导我如何做这件事。提前感谢

Answer 1

是的，你可以通过使用WindowListener来做到这一点。

 public void windowClosed(WindowEvent e) {
        //This will only be seen on standard output.
        displayMessage("WindowListener method called: windowClosed.");
    }
    public void windowOpened(WindowEvent e) {
        displayMessage("WindowListener method called: windowOpened.");
    }
    public void windowIconified(WindowEvent e) {
        displayMessage("WindowListener method called: windowIconified.");
    }
    public void windowDeiconified(WindowEvent e) {
        displayMessage("WindowListener method called: windowDeiconified.");
    }
    public void windowActivated(WindowEvent e) {
        displayMessage("WindowListener method called: windowActivated.");
    }
    public void windowDeactivated(WindowEvent e) {
        displayMessage("WindowListener method called: windowDeactivated.");
    }
    public void windowGainedFocus(WindowEvent e) {
        displayMessage("WindowFocusListener method called: windowGainedFocus.");
    }
    public void windowLostFocus(WindowEvent e) {
        displayMessage("WindowFocusListener method called: windowLostFocus.");
    }
    public void windowStateChanged(WindowEvent e) {
        displayStateMessage(
          "WindowStateListener method called: windowStateChanged.", e);

请参阅本教程了解更多细节。
但是对于您的场景，我建议您使用适配器类(因为您只需要一个事件，所以不需要厌倦并实现所有方法)，所以这里有一个例子，根据您的需求

import java.awt.event.WindowAdapter;  
import java.awt.event.WindowEvent;  
import javax.swing.JFrame;  
import javax.swing.JOptionPane;  
public class NoCloseFrame extends JFrame {  
    public static void main( String[] arg ) {  
        new NoCloseFrame();  
    }  
    public NoCloseFrame() {  
        super( "No Close Frame!" );  
        setDefaultCloseOperation( DO_NOTHING_ON_CLOSE );  
        setSize( 300, 300 );  
        setVisible( true );  
        addWindowListener( new AreYouSure() );  
    }  
    private class AreYouSure extends WindowAdapter {  
        public void windowClosing( WindowEvent e ) {  
            int option = JOptionPane.showOptionDialog(  
                    NoCloseFrame.this,  
                    "Are you sure you want to quit?",  
                    "Exit Dialog", JOptionPane.YES_NO_OPTION,  
                    JOptionPane.WARNING_MESSAGE, null, null,  
                    null );  
            if( option == JOptionPane.YES_OPTION ) {  
                System.exit( 0 );  
            }  
        }  
    }  
}  

Answer 2

您可以按照以下步骤操作:

1. 将frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);行替换为frame.setDefaultCloseOperation(JFrame.DO_NOTHING_ON_CLOSE);

2. 实现WindowListener并覆盖其所有抽象方法。

3. 这样重写public void windowClosing(WindowEvent e)方法:

    @Override
    public void windowClosing(WindowEvent e){
          int result = JOptionPane.showConfirmDialog(null, "Are you sure,"Confirm",JOptionPane.YES_NO_OPTION,JOptionPane.QUESTION_MESSAGE);
          if(result == JOptionPane.YES_OPTION){
                  System.exit(0);
          }else{
                  //Do nothing
          }
    }