Wait cursor and disable java application

Question

I want to have the user press a button to kick off a background thread.

While the thread is processing, I want two things to happen:

1) A WAIT_CURSOR should be displayed.

2) The application should not respond to mouse events.

As per the setCursor documentation "This cursor image is displayed when the contains method for this component returns true for the current cursor location, and this Component is visible, displayable, and enabled. ".

I want my application to be disabled while this background thread is processing.

Any ideas how to get the functionality I want?

import java.awt.Component;
import java.awt.Cursor;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;

import javax.swing.JButton;
import javax.swing.JFrame;
import javax.swing.JOptionPane;
import javax.swing.JPanel;
import javax.swing.SwingUtilities;

public class WaitCursor extends JFrame
{
    private static final long    serialVersionUID    = 1L;

    public WaitCursor()
    {
        setResizable(false);

        setName(getClass().getSimpleName());
        setTitle("My Frame");
        setSize(300, 300);

        getContentPane().add(new MyButtonPanel());

    }

    private class MyButtonPanel extends JPanel
    {

        private static final long    serialVersionUID    = 1L;

        public MyButtonPanel()
        {
            JButton btnStart = new JButton("Start");
            btnStart.addActionListener(new BtnStartActionListener());
            add(btnStart);
        }

        private class BtnStartActionListener implements ActionListener
        {
            public void actionPerformed(ActionEvent e)
            {
                // Change to WAIT_CURSOR
                Component root = SwingUtilities.getRoot((JButton) e.getSource());
                JOptionPane.showMessageDialog(root, "Wait 10 seconds");
                root.setCursor(Cursor.getPredefinedCursor(Cursor.WAIT_CURSOR));

                // TODO: Disabling the root component prevents the WAIT_CURSOR from being displayed
                root.setEnabled(false);
                new Thread(new TimeKiller(root)).start();
            }
        }
    }

    private class TimeKiller implements Runnable
    {
        Component    _root;

        public TimeKiller(Component root)
        {
            _root = root;
        }

        public void run()
        {
            try
            {
                Thread.sleep(10 * 1000);
            }
            catch (InterruptedException e)
            {
                // Ignore it
            }
            // Change back to DEFAULT CURSOR
            JOptionPane.showMessageDialog(_root, "Done waiting");
            _root.setCursor(Cursor.getDefaultCursor());
            _root.setEnabled(true);
        }
    }

    private static void createAndShowGUI()
    {
        // Create and set up the window.
        WaitCursor frame = new WaitCursor();
        frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
        frame.setVisible(true);
    }

    public static void main(String[] args)
    {
        SwingUtilities.invokeLater(new Runnable()
        {
            public void run()
            {
                try
                {
                    createAndShowGUI();
                }
                catch (Exception e)
                {
                    e.printStackTrace();
                    System.exit(0);
                }
            }
        });
    }

}

Answer 1

One way to disable it is to use the glass pane to block mouse input.

For example:

import java.awt.Cursor;
import java.awt.Dimension;
import java.awt.event.ActionEvent;
import java.awt.event.MouseAdapter;

import javax.swing.*;

@SuppressWarnings("serial")
public class WaitCursor2 extends JPanel {

   private static final int PREF_W = 400;
   private static final int PREF_H = PREF_W;
   private JComponent glassPane;
   private JButton runBackgroundProcBtn;
   private JTextArea textarea = new JTextArea(15, 30);

   public WaitCursor2(JComponent glassPane) {
      this.glassPane = glassPane;
      glassPane.setFocusable(true);
      glassPane.addMouseListener(new MouseAdapter() {
      }); // so it will trap mouse events.

      add(new JTextField(10));
      add(runBackgroundProcBtn = new JButton(new AbstractAction(
            "Run Background Process") {

         @Override
         public void actionPerformed(ActionEvent arg0) {
            runBackgroundProcessAction();
         }
      }));
      add(new JScrollPane(textarea));
   }

   private void runBackgroundProcessAction() {
      disableSystem(true);
      glassPane.setVisible(true);
      new SwingWorker<Void, Void>() {
         @Override
         protected Void doInBackground() throws Exception {
            long sleepTime = 5000;
            Thread.sleep(sleepTime);
            return null;
         }

         @Override
         protected void done() {
            disableSystem(false);
         }
      }.execute();
   }

   public void disableSystem(boolean disable) {
      glassPane.setVisible(disable);
      runBackgroundProcBtn.setEnabled(!disable);
      if (disable) {
         System.out.println("started");
         glassPane.requestFocusInWindow(); // so can't add text to text components
         glassPane.setCursor(Cursor.getPredefinedCursor(Cursor.WAIT_CURSOR));
      } else {
         System.out.println("done");
         glassPane.setCursor(Cursor.getDefaultCursor());
      }
   }

   @Override
   public Dimension getPreferredSize() {
      return new Dimension(PREF_W, PREF_H);
   }

   private static void createAndShowGui() {
      JFrame frame = new JFrame("WaitCursor2");
      WaitCursor2 mainPanel = new WaitCursor2((JComponent) frame.getGlassPane());

      frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
      frame.getContentPane().add(mainPanel);
      frame.pack();
      frame.setLocationByPlatform(true);
      frame.setVisible(true);
   }

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

The glass pane will trap mouse events if it set visible and given a MouseListener. It will lose t his ability if it is set invisible. Likewise it will pull the caret from text components if you make it focusable and give it focus.

Answer 2

added a field current_active and at method actionPerformed, do a simple check. Albeit it is not perfect but for simple app, i think this do the trick. A crude way of solving your two requirement. :-) Hope it works for you too.

import java.awt.Component;
import java.awt.Cursor;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;

import javax.swing.JButton;
import javax.swing.JFrame;
import javax.swing.JOptionPane;
import javax.swing.JPanel;
import javax.swing.SwingUtilities;


public class WaitCursor extends JFrame
{
    private static boolean current_active = false;

    public WaitCursor()
    {
        setResizable(false);

        setName(getClass().getSimpleName());
        setTitle("My Frame");
        setSize(300, 300);

        getContentPane().add(new MyButtonPanel());
    }

    private class MyButtonPanel extends JPanel
    {

        public MyButtonPanel()
        {
            JButton btnStart = new JButton("Start");
            btnStart.addActionListener(new BtnStartActionListener());
            add(btnStart);
        }

        private class BtnStartActionListener implements ActionListener
        {



            // change to wait_cursor
            public void actionPerformed(ActionEvent e)
            {
                if (!current_active)
                {
                    Component root = SwingUtilities.getRoot((JButton) e.getSource());
                    JOptionPane.showMessageDialog(root, "Wait 10 seconds");
                    root.setCursor(Cursor.getPredefinedCursor(Cursor.WAIT_CURSOR));

                    // TODO: Disabling the root component prevents the WAIT_CURSOR from being displayed
                    //root.setEnabled(false);
                    current_active = true;
                    new Thread(new TimeKiller(root)).start();   

                }
            }
        }   
    }

    private class TimeKiller implements Runnable
    {
        Component m_root;

        public TimeKiller(Component p_root)
        {
            m_root = p_root;

        }       

        @Override
        public void run()
        {
            try
            {
                Thread.sleep(10 * 1000);                
            }
            catch (InterruptedException e)
            {
                //Ignore it
            }
            // Change back to DEFAULT CURSOR
            JOptionPane.showMessageDialog(m_root, "Done waiting");
            m_root.setCursor(Cursor.getDefaultCursor());
            current_active = false;
        }

    }

    // create and setup the window.
    public static void createAndShowGUI() 
    {
        WaitCursor frame = new WaitCursor();
        frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
        frame.setVisible(true);

    }

    public static void main(String[] args)
    {
        SwingUtilities.invokeLater(new Runnable()
        {
            @Override
            public void run()
            {
                try
                {
                    createAndShowGUI();
                }
                catch (Exception e)
                {
                    e.printStackTrace();
                    System.exit(0);
                }
            }
        });
    }

}