Set location of JDialog relative to JFrame

问题:

Is there a way to set a dialog location relative to a JFrame?

I would like to center the dialog to the frame that houses my GUI, instead the dialog often appears in the center of the screen rather than within the GUI.

回答1:

Is there a way to set a location relative to another JFrame

You can:

• pass JFrame as argument for JDialog.setLocationRelativeTo(Component c)
• set to desired Point from JFrame to JDialog.setLocation(Point p)

EDIT

all Swing code must be done on EventDispatchThread, meaning that setVisible(true) should be wrapped into invokeLater

EDIT2

when using the JFrame as Component c I am getting a cannot find symbol error

not possible, some small mistake

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

public class ClosingFrameDialog extends JFrame {

    private JFrame frame = new JFrame();
    private static final long serialVersionUID = 1L;
    private JMenuBar MenuBar;
    private JMenu File;
    private JMenuItem Exit;
    private JMenuItem ShowDialog;
    private JDialog dialog;
    private Point location;

    public ClosingFrameDialog() {
        Exit = new JMenuItem(" Exit ");
        Exit.addActionListener(new ExitListener());
        ShowDialog = new JMenuItem(" Show Dialog ");
        ShowDialog.addActionListener(showingDialog());
        File = new JMenu(" File ");
        File.add(Exit);
        File.add(ShowDialog);
        MenuBar = new JMenuBar();
        MenuBar.add(File);
        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);
        SwingUtilities.invokeLater(new Runnable() {

            @Override
            public void run() {
                createDialog();
            }
        });
    }

    private void createDialog() {
        JButton btn = new JButton(" Save changes ");
        btn.addActionListener(new ActionListener() {

            public void actionPerformed(ActionEvent e) {
                //some stuff for saving whatewer programatically
                dialog.setVisible(false);
            }
        });
        JButton btn1 = new JButton(" Ignore changes ");
        btn1.addActionListener(new ActionListener() {

            public void actionPerformed(ActionEvent e) {
                dialog.setLocationRelativeTo(frame);
                dialog.setVisible(false);
            }
        });
        dialog = new JDialog();
        dialog.add(btn);
        dialog.add(btn1);
        dialog.setVisible(false);
        dialog.setAlwaysOnTop(true);
        dialog.setModal(true);
        dialog.setLayout(new GridLayout(2, 0, 10, 10));
        JPanel pane = (JPanel) dialog.getContentPane();
        pane.setBorder(new EmptyBorder(10, 10, 10, 10));
        dialog.addWindowListener(closeListener);
        dialog.pack();
    }
//
    private 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 == 0) {
                System.exit(1);
            }
        }

        @Override
        public void windowIconified(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 == 0) {
                //System.exit(1);
            }
        }
    };
//
    private WindowListener closeListener = new WindowAdapter() {

        @Override
        public void windowClosing(WindowEvent e) {
            int confirm = JOptionPane.showOptionDialog(dialog,
                    "Are you want to save changes",
                    "Exit Confirmation", JOptionPane.YES_NO_OPTION,
                    JOptionPane.QUESTION_MESSAGE, null, null, null);
            if (confirm == 0) {
                //some stuff for saving whatewer programatically
                dialog.setVisible(true);
            } else if (confirm == 1) {// nothing only hide JDialog
                dialog.setVisible(true);
            }
        }
    };

    private Action showingDialog() {
        return new AbstractAction("Show Dialog") {

            private static final long serialVersionUID = 1L;

            @Override
            public void actionPerformed(ActionEvent e) {
                Runnable doRun = new Runnable() {

                    @Override
                    public void run() {
                        dialog.setVisible(false);
                        location = frame.getLocationOnScreen();
                        int x = location.x;
                        int y = location.y;
                        //dialog.setLocation(x, y);
                        dialog.setLocationRelativeTo(frame);
                        dialog.setVisible(true);
                    }
                };
                SwingUtilities.invokeLater(doRun);
            }
        };
    }

    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 == 0) {
                System.exit(1);
            }
        }
    }

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

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

回答2:

The method you want is: setLocationRelativeTo()

Adding it with null to the JFrame, will center it on the screen. Adding the JFrame to the dialog will center it on the jframe.

Cheers.

import javax.swing.JDialog;
import javax.swing.JFrame;

public class Centered
{
    public static void main( String args[] )
    {
        JFrame jFrame = new JFrame();

        jFrame.setSize( 250 , 250 );
        jFrame.setLocationRelativeTo( null );
        jFrame.setVisible( true );

        JDialog jDialog = new JDialog();
        jDialog.setLocationRelativeTo( jFrame );
        jDialog.setVisible( true );
    }
}

回答3:

You should give this as the argument for the parent parameter when you construct the dialog (when you call it from a JFrame class that is usually your mainform). Unless you give code in your question, I cannot give more detailed help...

Edit: To center it within the parent, do this:

 MyDialog dialog = new MyDialog(this, true); //or false for non-modal
 dialog.setLocation(this.getWidth/2 - dialog.getWidth/2, this.getHeight/2 - dialog.getHeight/2);
 dialog.setVisible(true);