问题
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:
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();
}
but application still close when i click x button on the windows. why? can you help me?
I can't use
setDefaultCloseOperation(DISPOSE_ON_CLOSE);
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);
}
but it still continue to terminate my entire app.
回答1:
Adding a New Code with no WindowListener part as explained by @JBNizet, the very right thing. The default behaviour just hides the window, nothing is lost, you simply have to bring it back, every value inside it will remain as is, below is the sample program for further help :
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);
}
}
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);
}
}
回答2:
don't create a new JFrame, for new container use JDialog, if you want to hide the JFrame then better would be override proper e.g DefaultCloseOperations(JFrame.HIDE_ON_CLOSE), method JFrame.EXIT_ON_CLOSE teminating current JVM instance simlair as calll for System.exit(int)
EDIT
but it still continue to terminate my entire app.
1) then there must be another issue, your code maybe call another JFrame or formWindowClosing <> WindowClosing, use implemented method from API
public void windowClosing(WindowEvent e) {
2) I'b preferred DefaultCloseOperations(JFrame.HIDE_ON_CLOSE),
3) use JDialog instead of JFrame
import javax.swing.*;
import java.awt.*;
import java.awt.event.*;
public class ClosingFrame extends JFrame {
private JMenuBar MenuBar = new JMenuBar();
private static JFrame frame = new JFrame();
private static JFrame frame1 = new JFrame("DefaultCloseOperation(JFrame.HIDE_ON_CLOSE)");
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) {
frame.setVisible(false);
/*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);
}*/
}
};
JButton btn = new JButton("Show second JFrame");
btn.addActionListener(new ActionListener() {
public void actionPerformed(ActionEvent e) {
frame1.setVisible(true);
}
});
frame.add(btn, BorderLayout.SOUTH);
frame.addWindowListener(exitListener);
frame.setDefaultCloseOperation(JFrame.HIDE_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();
JButton btn = new JButton("Show first JFrame");
btn.addActionListener(new ActionListener() {
public void actionPerformed(ActionEvent e) {
frame.setVisible(true);
}
});
frame1.add(btn, BorderLayout.SOUTH);
frame1.setDefaultCloseOperation(JFrame.HIDE_ON_CLOSE);
frame1.setPreferredSize(new Dimension(400, 300));
frame1.setLocation(100, 400);
frame1.pack();
frame1.setVisible(true);
}
});
}
}
回答3:
You could avoid the listener completely and use
setDefaultCloseOperation(DISPOSE_ON_CLOSE);
Note that the default value is HIDE_ON_CLOSE, so the behavior you want should be the default behavior. Maybe you registered another listener that exits the application.
See http://docs.oracle.com/javase/6/docs/api/javax/swing/JFrame.html#setDefaultCloseOperation%28int%29
回答4:
It's hard to pinpoint exactly why you are experiencing the behavior stated without seeing a little more of the set-up code, however it may be due to defaultCloseOperation set to EXIT_ON_CLOSE.
Here's a link to a demo displaying the properties you are looking for although the structure is a bit different. Have a look: http://docs.oracle.com/javase/tutorial/uiswing/examples/components/FrameworkProject/src/components/Framework.java
来源：https://stackoverflow.com/questions/9725311/how-to-override-windowsclosing-event-in-jframe