Changing mouse pointer using setCursor()

Question

Hi- I've got a single threaded JFrame-based application in which I want to change the mouse pointer to indicate 'busy' when it's doing stuff eg. loading a file. So within my extended JFrame method for handling menu selections I've got:
public class Layout extends JFrame
    // For items in the main menu
    // (the sub-class contains either a JMenuItem or JCheckBoxMenuItem).
    abstract class MenuItem implements ActionListener
        abstract JMenuItem menuItemAbs(); // get the menu item component
        abstract void handlerAbs(); // perform the menu's action
        // Menu item has been selected.
        public void actionPerformed(ActionEvent e)
            Cursor cursor = Layout.this.getCursor();
            Layout.this.setCursor(Cursor.getPredefinedCursor(Cursor.WAIT_CURSOR));
            handlerAbs();
            Layout.this.setCursor(cursor);
        }But the mouse pointer doesn't always change. If handler() just does some processing without user interaction, the pointer does change. But in the case of loading a file, where first the user selects the file using a JFileChooser, it doesn't.
Is this because JFileChooser does its own setCursor()? But even if it does, presumably it does another setCursor() to restore my WAIT_CURSOR before it returns, so why don't I see the WAIT_CURSOR while the file is loading (which takes seconds)?
Cheers
John
EDIT: BTW running under Linux, Java v6 update 7
Edited by: matth1j on Nov 12, 2008 2:15 AM

Answer 1

Ok, thanks - full demo program below.
When you hit the ok button (just 5 second sleep), the mouse pointer changes to 'busy'. It reverts to normal if you move the pointer off the frame, but goes back to 'busy' if you move it back onto the frame.
When you hit the bad button (brings up file chooser, then does 5 second sleep), the pointer changes to 'busy' while the pointer is over the frame, and reverts to normal when the pointer is moved off the frame. But if you select a file or cancel the file chooser and move the pointer back into the main frame before the 5 seconds is up, the pointer doesn't go back to 'busy' again. I would expect it to show 'busy' while over the frame until the 5 seconds is up.
Any ideas?
package test;
import java.awt.Cursor;
import java.awt.EventQueue;
import java.awt.event.*;
import javax.swing.*;
public class Main
    public static void main(String[] args)
        EventQueue.invokeLater(new Runnable()
            public void run()
                new Test();
class Test extends JFrame
    public Test()
        super();
        this.setDefaultCloseOperation(EXIT_ON_CLOSE);
        JPanel panel = new JPanel();
        panel.add(new Button("ok"));
        panel.add(new Button("bad"));
        add(panel);
        pack();
        repaint();
        setVisible(true);
    class Button extends JButton implements ActionListener
        Button(String text)
            super(text);
            addActionListener(this);
        public void actionPerformed(ActionEvent e)
            Cursor cursor = Test.this.getCursor();
            Test.this.setCursor(Cursor.getPredefinedCursor(Cursor.WAIT_CURSOR));
            if (!e.getActionCommand().equals("ok"))
                (new JFileChooser()).showOpenDialog(null);
            try
                Thread.sleep(5000);
            catch (Exception ex)
                ex.printStackTrace();
            Test.this.setCursor(cursor);
}Edited by: matth1j on Nov 12, 2008 2:44 AM code tidy
Edited by: matth1j on Nov 12, 2008 2:45 AM code tidy