如何在JFrame中覆盖windowsClosing事件 [英] How to override windowsClosing event in JFrame

问题描述

我正在开发一个JFrame，它具有一个显示另一个JFrame的按钮.在第二个JFrame上，我想重写WindowsClosing事件以隐藏此框架，但不关闭所有应用程序.所以我喜欢这样:

i'm developing a JFrame which has a button to show another JFrame. On the second JFrame i want to override WindowsClosing event to hide this frame but not close all the application. So i do like this:

在第二个JFrame上

On second JFrame

addWindowListener(new java.awt.event.WindowAdapter() {
    public void windowClosing(java.awt.event.WindowEvent evt) {
         formWindowClosing(evt);
    }
});

private void formWindowClosing(java.awt.event.WindowEvent evt) {
    this.dispose();
}

但是当我单击Windows上的x按钮时，应用程序仍然关闭.为什么?你能帮我吗?

but application still close when i click x button on the windows. why? can you help me?

我不能使用

setDefaultCloseOperation(DISPOSE_ON_CLOSE);

因为我需要再次展示从第一个JFrame进行操作期间在其中添加了一些信息的JFrame.所以我用属性visible false初始化了第二个JFrame.如果我使用dispose，那么第二个JFrame将丢失我添加的信息.所以我用

because i need to show again that JFrame with some information added in it during operations from first JFrame. So i init second JFrame with attribute visible false. if i use dispose i lose the information added in a second moment by the other JFrame. so i use

private void formWindowClosing(java.awt.event.WindowEvent evt) {
    this.setVisible(false);
}

但它仍然继续终止我的整个应用程序.

but it still continue to terminate my entire app.

推荐答案

添加一个没有WindowListener部分的新代码，正如@JBNizet所解释的那样，这是非常正确的.默认行为只是隐藏窗口，没有任何损失，您只需将其恢复原样，其中的每个值都将保持不变，下面是示例程序，以提供进一步的帮助:

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

public class TwoFrames
{
    private SecondFrame secondFrame;
    private int count = 0;

    private void createAndDisplayGUI()
    {
        JFrame frame = new JFrame("JFRAME 1");
        frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
        frame.setLocationByPlatform(true);

        secondFrame = new SecondFrame();
        secondFrame.createAndDisplayGUI();
        secondFrame.tfield.setText("I will be same everytime.");

        JPanel contentPane = new JPanel();  
        JButton showButton = new JButton("SHOW JFRAME 2");
        showButton.addActionListener(new ActionListener()
        {
            public void actionPerformed(ActionEvent ae)
            {
                secondFrame.tfield.setText(secondFrame.tfield.getText() + count);
                count++;
                if (!(secondFrame.isShowing()))
                    secondFrame.setVisible(true);
            }
        });

        frame.add(contentPane, BorderLayout.CENTER);
        frame.add(showButton, BorderLayout.PAGE_END);
        frame.setSize(200, 200);
        frame.setVisible(true);
    }

    public static void main(String... args)
    {
        SwingUtilities.invokeLater(new Runnable()
        {
            public void run()
            {
                new TwoFrames().createAndDisplayGUI();
            }
        });
    }
}

class SecondFrame extends JFrame
{
    private WindowAdapter windowAdapter;
    public JTextField tfield;

    public void createAndDisplayGUI()
    {
        setLocationByPlatform(true);

        JPanel contentPane = new JPanel();

         tfield = new JTextField(10);

        addWindowListener(windowAdapter);
        contentPane.add(tfield);

        getContentPane().add(contentPane);
        setSize(300, 300);      
    }
}

这是您想要的吗，请尝试以下代码:

Is this what you want, try this code :

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

public class TwoFrames
{
    private SecondFrame secondFrame;

    private void createAndDisplayGUI()
    {
        JFrame frame = new JFrame("JFRAME 1");
        frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
        frame.setLocationByPlatform(true);

        secondFrame = new SecondFrame();
        secondFrame.createAndDisplayGUI();
        secondFrame.tfield.setText("I will be same everytime.");

        JPanel contentPane = new JPanel();  
        JButton showButton = new JButton("SHOW JFRAME 2");
        showButton.addActionListener(new ActionListener()
        {
            public void actionPerformed(ActionEvent ae)
            {
                if (!(secondFrame.isShowing()))
                    secondFrame.setVisible(true);
            }
        });

        frame.add(contentPane, BorderLayout.CENTER);
        frame.add(showButton, BorderLayout.PAGE_END);
        frame.setSize(200, 200);
        frame.setVisible(true);
    }

    public static void main(String... args)
    {
        SwingUtilities.invokeLater(new Runnable()
        {
            public void run()
            {
                new TwoFrames().createAndDisplayGUI();
            }
        });
    }
}

class SecondFrame extends JFrame
{
    private WindowAdapter windowAdapter;
    public JTextField tfield;

    public void createAndDisplayGUI()
    {
        setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
        setLocationByPlatform(true);

        JPanel contentPane = new JPanel();

         tfield = new JTextField(10);

        windowAdapter = new WindowAdapter()
        {
            public void windowClosing(WindowEvent we)
            {
                setDefaultCloseOperation(JFrame.HIDE_ON_CLOSE);
            }
        };

        addWindowListener(windowAdapter);
        contentPane.add(tfield);

        getContentPane().add(contentPane);
        setSize(300, 300);      
    }
}

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