How do I make my SwingWorker example work properly?

Question

I've made my own SwingWorker example to get familiar with how it works.

What I'm wanting to do is the following: When the button is clicked I want a progress bar appear until the task is done I want to simply remove the progress bar and add a string to the dialog.

When the button is clicked, the progress bar comes up but never goes away. (never removes the progress bar after 10 seconds and never places the label up)

Here is an SSCCE:

package swingtesting;

import java.awt.event.ActionEvent; 
import java.awt.event.ActionListener;
import javax.swing.JButton;
import javax.swing.JDialog;
import javax.swing.JFrame;
import javax.swing.JLabel;
import javax.swing.JProgressBar;
import javax.swing.SwingWorker;

public class SwingTesting {

    /**
     * Creates a frame that will hold a simple button to make use of SwingWorker
     */
     public static void main(String[] args) {
         // TODO code application logic here
         JFrame frame = new JFrame();
         JButton button = new JButton();

         button.addActionListener(new ActionListener() {
            public void actionPerformed(ActionEvent e) {
                new GuiWorker().execute();
            }
         });
         button.setText("Test Me");
         frame.getContentPane().add(button);
         frame.pack();
         frame.setVisible(true);
    }
}

class GuiWorker extends SwingWorker<Integer, Integer> {

    /*
     * This should just create a frame that will hold a progress bar until the
     * work is done. Once done, it should remove the progress bar from the dialog
     * and add a label saying the task complete.
     */

    private JFrame frame = new JFrame();
    private JDialog dialog = new JDialog(frame, "Swingworker test", true);
    private JProgressBar progressBar = new JProgressBar();


    public GuiWorker() {
        progressBar.setString("Waiting on time");
        progressBar.setStringPainted(true);
        progressBar.setIndeterminate(true);
        dialog.getContentPane().add(progressBar);
        dialog.pack();
        dialog.setVisible(true);
    }

    @Override
    protected Integer doInBackground() throws Exception {
        Thread.sleep(10000);
        return 0;
    }

    @Override
    protected void done() {
        JLabel label = new JLabel("Task Complete");
        dialog.getContentPane().remove(progressBar);
        dialog.getContentPane().add(label);
    }

}

You can take a look at [this answer](http://stackoverflow.com/questions/8916721/java-swing-update-label/8917565#8917565) and compare with your code. The Swing tutorial also contains an example (link is available in the class javadoc of `JProgressBar`) — Robin, Apr 19 '12 at 21:34

score 13 · Accepted Answer · answered Apr 19 '12 at 21:40

Here an updated version of your code which works

import java.awt.EventQueue;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import javax.swing.JButton;
import javax.swing.JDialog;
import javax.swing.JFrame;
import javax.swing.JLabel;
import javax.swing.JProgressBar;
import javax.swing.SwingWorker;

public class SwingTesting {

  public static void main(String[] args) {
    EventQueue.invokeLater( new Runnable() {
      @Override
      public void run() {
        JFrame frame = new JFrame();
        JButton button = new JButton();
        button.addActionListener(new ActionListener() {
          @Override
          public void actionPerformed(ActionEvent e) {
            new GuiWorker().execute();
          }
        });
        button.setText("Test Me");
        frame.getContentPane().add(button);
        frame.pack();
        frame.setVisible(true);
      }
    } );

  }
}

class GuiWorker extends SwingWorker<Integer, Integer> {

  /*
  * This should just create a frame that will hold a progress bar until the
  * work is done. Once done, it should remove the progress bar from the dialog
  * and add a label saying the task complete.
  */

  private JFrame frame = new JFrame();
  private JDialog dialog = new JDialog(frame, "Swingworker test", true);
  private JProgressBar progressBar = new JProgressBar();


  public GuiWorker() {
    progressBar.setString("Waiting on time");
    progressBar.setStringPainted(true);
    progressBar.setIndeterminate(true);
    dialog.getContentPane().add(progressBar);
    dialog.pack();
    dialog.setModal( false );
    dialog.setVisible(true);
  }

  @Override
  protected Integer doInBackground() throws Exception {
    System.out.println( "GuiWorker.doInBackground" );
    Thread.sleep(1000);
    return 0;
  }

  @Override
  protected void done() {
    System.out.println("done");
    JLabel label = new JLabel("Task Complete");
    dialog.getContentPane().remove(progressBar);
    dialog.getContentPane().add(label);
    dialog.getContentPane().validate();
  }

}

Key point is that setting a model dialog visible blocks until the dialog is disposed. So making it non-modal fixed it + the validate call on the content pane when you switch components. I also adjusted your main method to run on the EDT, and added some System.out calls. If you remove the setModal( false ) call you will see those statements are not printed until you close the dialog

Thank you for pointing that out! I guess I should have looked to see whether there was a `setModal` method in the first place. I also took note the change in main, thank you for pointing that out. I just read about it here: http://java.sun.com/developer/technicalArticles/javase/swingworker/ I do have one issue with it though, by changing Modal to false, it allows the user to click the button more than once. — WilliamShatner, Apr 19 '12 at 21:58
@WilliamShatner: there's no need to make the dialog non-modal. Simply display the dialog after starting the SwingWorker. This can be done either from the calling class, the one executing the SwingWorker, by first calling execute, and then showing the dialog, or it can be done from the SwingWorker, but if from the latter, you'll have to make your own pseudo-execute method that calls super's execute, and then shows the dialog. Note that you can't override `execute()` itself since it's final. — Hovercraft Full Of Eels, Apr 20 '12 at 01:51
@WilliamShatner you can disable the button when you start the SwingWorker, and re-enable it afterwards — Robin, Apr 20 '12 at 05:41
@Robin I think I am sticking to your method however I'm unsure how I would disable the button from inside its own actionPerformed unless the button was global? — WilliamShatner, May 01 '12 at 22:43
@WilliamShatner Two solutions: you retrieve the button from the ActionEvent#getSource() or you make the button final — Robin, May 02 '12 at 06:04

score 11 · Answer 2 · answered Apr 20 '12 at 04:13

There's no need to make the dialog non-modal. Simply display the dialog after starting the SwingWorker. This can be done either from the calling class, the one executing the SwingWorker, by first calling execute, and then showing the dialog, or it can be done from the SwingWorker, but if from the latter, you'll have to make your own pseudo-execute method that calls super's execute, and then shows the dialog. Note that you can't override execute() itself since it's final.

For example...

import java.awt.CardLayout;
import java.awt.Window;
import java.awt.Dialog.ModalityType;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import java.beans.PropertyChangeEvent;
import java.beans.PropertyChangeListener;
import java.util.concurrent.ExecutionException;

import javax.swing.*;

@SuppressWarnings("serial")
public class SwingTesting2 {

   private static void createAndShowGui() {
      final JFrame frame = new JFrame("SwingTesting2");
      final JDialog dialog = new JDialog(frame, "Dialog",
            ModalityType.APPLICATION_MODAL);
      final DialogPanel dialogPanel = new DialogPanel();
      dialog.getContentPane().add(dialogPanel.getMainPanel());
      dialog.pack();
      dialog.setLocationRelativeTo(frame);

      JButton button = new JButton(new AbstractAction("Test Me") {

         @Override
         public void actionPerformed(ActionEvent actEvt) {
            final GuiWorker2 guiWorker = new GuiWorker2();
            guiWorker.addPropertyChangeListener(new PropertyChangeListener() {

               @Override
               public void propertyChange(PropertyChangeEvent pcEvt) {
                  if (pcEvt.getPropertyName().equals("state")) {
                     if (pcEvt.getNewValue() == SwingWorker.StateValue.DONE) {
                        try {
                           dialogPanel.done(guiWorker.get());
                        } catch (InterruptedException e) {
                           e.printStackTrace();
                        } catch (ExecutionException e) {
                           e.printStackTrace();
                        }
                     }
                  } else if (pcEvt.getPropertyName().equals("progress")) {
                     dialogPanel.setProgress((Integer)pcEvt.getNewValue());
                  }
               }
            });

            guiWorker.execute();
            dialogPanel.start();
            dialog.setVisible(true);
         }
      });

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

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

class GuiWorker2 extends SwingWorker<Integer, Integer> {
   private static final int MAX_COUNT = 20;
   private static final long SLEEP_TIME = 100;
   private int count = 0;

   @Override
   protected Integer doInBackground() throws Exception {
      while (count < MAX_COUNT) {
         Thread.sleep(SLEEP_TIME);
         count++;
         setProgress((100 * count) / MAX_COUNT);
      }
      return count;
   }
}

@SuppressWarnings("serial")
class DialogPanel {
   public static final String PROGRESS_BAR = "Progress Bar";
   public static final String DONE = "Done";
   private static final int TIMER_DELAY = 2000;
   private CardLayout cardLayout = new CardLayout();
   private JPanel mainPanel = new JPanel(cardLayout);
   private JLabel doneLabel = new JLabel("Done", JLabel.CENTER);
   private JProgressBar progressBar = new JProgressBar();

   public DialogPanel() {
      progressBar.setString("Waiting on time");
      progressBar.setStringPainted(true);
      progressBar.setIndeterminate(false);

      mainPanel.add(progressBar, PROGRESS_BAR);
      mainPanel.add(doneLabel, DONE);
   }

   public void setProgress(Integer newValue) {
      progressBar.setValue(newValue);
   }

   public void start() {
      cardLayout.show(mainPanel, PROGRESS_BAR);
      progressBar.setValue(0);
   }

   public void done(int countValue) {
      doneLabel.setText(DONE + ". Count: " + countValue);
      cardLayout.show(mainPanel, DONE);
      new Timer(TIMER_DELAY, new ActionListener() {

         @Override
         public void actionPerformed(ActionEvent e) {
            Window win = SwingUtilities.getWindowAncestor(mainPanel);
            win.dispose();
         }
      }){{setRepeats(false);}}.start();
   }

   public JPanel getMainPanel() {
      return mainPanel;
   }

}

@Hovercraft The example was great. Tested it out and it worked nicely. I'm not too familiar with what all the code does but I played around with it. I'm also not too fond of adding another class to the picture, but I'm glad you posted this. Upvoted :) — WilliamShatner, May 01 '12 at 22:43
@William: thanks for the comments. Best of luck with your project! — Hovercraft Full Of Eels, May 01 '12 at 22:59
@HovercraftFullOfEels You've been quite helpful in each of my posts and I wish there was more to offer than a thank you. I'm still learning and hopefully I'll be able to come back and fully understand all of the code above. I hope you're around for future questions, because I know I'll have plenty more. Thanks again! — WilliamShatner, May 01 '12 at 23:08
@HovercraftFullOfEels Not sure if you care, but I just wanted to say that your `propertyChangeListener` was a great example for a new project I just started :) thanks again! — WilliamShatner, May 29 '12 at 19:54

How do I make my SwingWorker example work properly?

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