如何移动JPanel

Question

I have a JDialog which contains JPanel and other elements like JTextField . I want to move JDialog from one location to another after it is loaded on screen. When I try to use jdialog.setLocation() , I am not able to move JDialog and also all other components added to it becomes invisible.

Can anyone tell me what might be wrong with my approach?

Answer 1

Regarding Gilbert's assertion that a dialog can't be moved after being set visible, please run this:

import java.awt.Component;
import java.awt.Dialog.ModalityType;
import java.awt.Dimension;
import java.awt.Toolkit;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;

import javax.swing.*;

public class MovingDialog {
   private static void createAndShowGui() {
      JPanel panel = new JPanel();
      panel.add(new JButton(new ShowMovingDialogAction()));
      JFrame frame = new JFrame("MovingDialog");
      frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
      frame.getContentPane().add(panel);
      frame.pack();
      frame.setLocationRelativeTo(null);
      frame.setVisible(true);
   }

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

class ShowMovingDialogAction extends AbstractAction {
   private JPanel panel = new JPanel();

   public ShowMovingDialogAction() {
      super("Show Moving Dialog");
      panel.add(new JLabel("label"));
      panel.add(new JTextField("TextField", 10));
      panel.add(new JButton("Button"));
   }

   @Override
   public void actionPerformed(ActionEvent e) {
      JFrame owner = (JFrame) SwingUtilities.getWindowAncestor((Component) e
            .getSource());
      final JDialog dialog = new JDialog(owner, "Dialog",
            ModalityType.APPLICATION_MODAL);
      dialog.getContentPane().add(panel);
      dialog.pack();
      dialog.setLocation(0, 0);

      int delay = 20;
      new Timer(delay , new ActionListener() {
         int x = 0;
         int y = 0;
         Dimension scrn = Toolkit.getDefaultToolkit().getScreenSize();

         @Override
         public void actionPerformed(ActionEvent e) {
            int maxX = scrn.width - dialog.getWidth();
            int maxY = scrn.height - dialog.getHeight();
            if (x < maxX  && y < maxY) {
               x++;
               y++;
               dialog.setLocation(x, y);
            } else {
               ((Timer)e.getSource()).stop();
            }
         }
      }).start();

      dialog.setVisible(true);

   }
}

Note that the animation Swing Timer must be started before calling setVisible(true). Perhaps that is what Gilbert was referring to.

Answer 2

If you try to do animation then you will have to initialize and start a new thread and do it there. The code inside the run() method of the thread should check if the dialog is visible and call dialog.setLocation() with modified values on each iteration.