SwingWorker does not update JProgressBar without Thread.sleep() in custom dialog panel

Question

I have a SwingWorker class which loads a text file and slices it to chunks for further processing.

This is the SwingWorker class:

public class ConverterWorker extends SwingWorker<String, String>
{
private final File f;
private final JLabel label;

public ConverterWorker(File f, JLabel label)
{
    this.f = f;
    this.label = label;
}

@Override
protected String doInBackground() throws Exception 
{
    NMTMain.convertableData = getDataSets(f);

    if(!NMTMain.convertableData.isEmpty())
    {
        return "Done";
    }
    else
    {
        publish("Failed to load the file!");
        return "Failed";
    }
}

@Override
public void done() 
{
    try 
    {
        label.setText(get());
    } 
    catch (Exception e)
    {
        e.printStackTrace(System.err);
        System.out.println("error");
    }
}

@Override
protected void process(List<String> chunks)
{
    label.setText(chunks.get(chunks.size() - 1));
}

public ArrayList<ArrayList<Convertable>> getDataSets(File f)
{
    ArrayList<ArrayList<Convertable>> dataSets = new ArrayList<ArrayList<Convertable>>();

    publish("Loading file...");
    setProgress(0);

    String[] data = loadFile(f);

    for(int i = 0; i< NMTMain.nodes.size(); i++)
    {
        dataSets.add(splitByNode(data, NMTMain.nodes.get(i).getName()));
    }

    setProgress(100);

    return dataSets;
}

private ArrayList<Convertable> splitByNode(String[] data, String name)
{
    ArrayList<Convertable> temp = new ArrayList<Convertable>();

    for(int i = 0; i < data.length; i++)
    {
        if(data[i].contains(name))
        {
            temp.add(new Convertable(data[i]));
        }
    }

    Collections.sort(temp);

    return temp;
}

private String[] loadFile(File f)
{
    String data = "";
    String[] nodes; 

    long fileLength = f.length();
    int bytesRead = -1;
    int totalBytesRead = 0;

    try 
    {
        if(f.exists()) 
        {
            Scanner scan = new Scanner(f);

            while(scan.hasNextLine()) 
            {
                String line = scan.nextLine();
                data = data + line + "\n";
                bytesRead = line.getBytes().length;
                totalBytesRead += bytesRead;
                int progress = (int) Math.round(((double) totalBytesRead / (double) fileLength) * 100d);

               /* try {
                    Thread.sleep(1);
                } catch (InterruptedException e) {
                    // TODO Auto-generated catch block
                    e.printStackTrace();
                }*/

                //publish("loading... " + String.valueOf(progress));
                setProgress(progress);
            }

            scan.close();
        }

    }
    catch (FileNotFoundException e) 
    {
        // TODO Auto-generated catch block
                e.printStackTrace();
    }

    nodes = data.split("\n\"\n");

    return nodes;        
}

This works fine when the Thread.sleep(1); is uncommented. However, when I comment the Thread.sleep(1); the class does not update the progressbar.

I call my class thorugh a button, here is the ActionListener:

loadInput.addActionListener(new ActionListener()
    {
        @Override
        public void actionPerformed(ActionEvent arg0)
        {   
            int returnval=NMTMain.fileChooser.showOpenDialog(NMTMain.MainFrame);

            if(returnval == 0)
            {
                File f=NMTMain.fileChooser.getSelectedFile();

                final ConverterWorker worker = new ConverterWorker(f, dialogPanel.getLabel());

                worker.addPropertyChangeListener(new PropertyChangeListener()
                {
                    @Override
                    public void propertyChange(final PropertyChangeEvent evt)
                    {
                        if("progress".equalsIgnoreCase(evt.getPropertyName())) 
                        {
                            dialogPanel.showProgressDialog("Conversion");
                            dialogPanel.setProgressBarValue((int) evt.getNewValue());
                        }

                        if(worker.isDone())
                        {
                            dialogPanel.showConfirmDialog("Conversion", "OK");
                        }
                    }
                });
                worker.execute();

            }
        }
    });

This should work fine without the sleep, so what is that I am doing wrong here?

UPDATE:

It turned out that my DialogPanel is not the best, and cause this behaviour.

Here is the DialogPanel class:

public class DialogPanel extends JDialog
{

private JLabel label;
private JPanel panel;
private JButton button;
private JProgressBar progressBar;

public DialogPanel()
{
    GridBagConstraints gbc = new GridBagConstraints();
    gbc.insets = new Insets(5,10,5,10);

    panel = new JPanel();
    panel.setLayout(new GridBagLayout());

    progressBar = new JProgressBar(0,100);
    progressBar.setVisible(false);
    progressBar.setStringPainted(true);

    setLabel(new JLabel("def text", SwingConstants.CENTER));

    button = new JButton("OK");
    button.setVisible(false);

    button.addActionListener(new ActionListener()
    {
        @Override
        public void actionPerformed(ActionEvent arg0)
        {
            // TODO Auto-generated method stub
            dispose();
        }
    });

    gbc.gridx = 0;
    gbc.gridy = 0;
    panel.add(getLabel(), gbc);
    gbc.gridy = 1;
    panel.add(progressBar, gbc);
    panel.add(button, gbc);

    this.setContentPane(panel);
    this.setLocationRelativeTo(null);
    this.setModalityType(Dialog.ModalityType.APPLICATION_MODAL);
    this.setResizable(false);
}

public void setProgressBarValue(int value)
{
    progressBar.setValue(value);
}

public void setProgressBarVisibility(boolean value)
{
    progressBar.setVisible(value);
}

public void setText(String text)
{
    getLabel().setText(text);
}

public void showProgressDialog(String title)
{
    progressBar.setVisible(true);
    button.setVisible(false);
    this.setTitle(title);
    this.pack();

    if(!this.isVisible())
    {
        this.setVisible(true);
    }
}

public void showConfirmDialog(String title, String buttontext)
{
    progressBar.setVisible(false);
    button.setVisible(true);
    this.setTitle(title);
    button.setText(buttontext);
    this.pack();

    if(!this.isVisible())
    {
        this.setVisible(true);
    }       
}

public JLabel getLabel() 
{
    return label;
}

public void setLabel(JLabel label)
{
    this.label = label;
}

public JProgressBar getProgressBar() 
{
    return progressBar;
}

@Override
public Dimension getPreferredSize()
{
    return new Dimension(200, 100);
}
}

It is probably a mess for professional eyes. How can I show the progressbar in a dialog which will have a confirm button to dispose the dialog when the process is done?

Solution:

I have changed from my DialogPanel class to ProgressMonitor and now everything is fine. Thank you for your time and advices.

Answer 1

The setProgress() API notes: "For performance purposes all these invocations are coalesced into one invocation with the last invocation argument only." Adding Thread.sleep(1) simply defers the coalescence; invoking println() introduces a comparable delay. Take heart that your file system is so fast; I would be reluctant to introduce an artificial delay. As a concrete example that illustrates the effect, I added intermediate reporting to this complete example, as shown below.

private static class LogWorker extends SwingWorker<TableModel, String> {
    private long fileLength;
    private long bytesRead;
    ...
    this.fileLength = file.length();
    ...
    while ((s = br.readLine()) != null) {
        publish(s);
        bytesRead += s.length();
        int progress = (int)(100 * bytesRead / fileLength);
        // System.out.println(progress);
        setProgress(progress);
    }
    ...
}

lw.addPropertyChangeListener((PropertyChangeEvent e) -> {
    if ("progress".equals(e.getPropertyName())) {
        jpb.setValue((Integer)e.getNewValue());
    }
    if ("state".equals(e.getPropertyName())) {
        SwingWorker.StateValue s = (SwingWorker.StateValue) e.getNewValue();
        if (s.equals(SwingWorker.StateValue.DONE)) {
            jpb.setValue(100);
        }
    }
});

Answer 2

I wanted to track my SwingWorker's progress with a JProgressBar within a JDialog. However my SwingWorker class could not handle my custom DialogPanel class. To achieve the same result, using the default ProgressMonitor class was the best option.

I have passed the ProgressMonitor to the SwingWorker through its constructor:

private final File f;
private final ProgressMonitor pm

public FileLoadWorker(File f, ProgressMonitor pm)
{
    this.f = f;
    this.pm = pm;
}

and changed the following methods like this:

@Override
public void done() 
{
    try 
    {
        pm.setNote(get());
    } 
    catch (Exception e)
    {
        e.printStackTrace(System.err);
        System.out.println("error");
    }
}

@Override
protected void process(List<String> chunks)
{
   pm.setNote(chunks.get(chunks.size() - 1));
}

The task's propertyChangeListener changed like this:

final FileLoadWorker worker = new FileLoadWorker(f, pm);

worker.addPropertyChangeListener(new PropertyChangeListener()
{
    @Override
    public void propertyChange(final PropertyChangeEvent evt)
    {
        if("progress".equalsIgnoreCase(evt.getPropertyName())) 
        {
            pm.setProgress((int) evt.getNewValue());
        }

        if("state".equals(evt.getPropertyName())) 
        {
            SwingWorker.StateValue s = (SwingWorker.StateValue) evt.getNewValue();
            if(s.equals(SwingWorker.StateValue.DONE))
            {
                pm.setProgress(100);
                pm.close();
                Toolkit.getDefaultToolkit().beep();
            }
        }

        if(pm.isCanceled())
        {
            pm.close();
            worker.cancel(true);
        }
    }
});
worker.execute();

Thanks to trashgod for the answer and comments about the state property.