Java SwingWorker update JProgressBar

import java.awt.LayoutManager;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import java.beans.PropertyChangeEvent;
import java.beans.PropertyChangeListener;

import javax.swing.BoxLayout;
import javax.swing.JButton;
import javax.swing.JFrame;
import javax.swing.JPanel;
import javax.swing.JProgressBar;
import javax.swing.SwingWorker;

public class Main {
  public static void main(String[] args) {
    JProgressBar progressBar = new JProgressBar(0, 10);

    CounterTask task = new CounterTask();
    task.addPropertyChangeListener(new PropertyChangeListener() {
      public void propertyChange(PropertyChangeEvent evt) {
        if ("progress".equals(evt.getPropertyName())) {
          progressBar.setValue((Integer) evt.getNewValue());
        }/*from   w  ww .  j  a va 2s .co  m*/
      }
    });
    JButton startButton = new JButton("Start");
    startButton.addActionListener(new ActionListener() {
      public void actionPerformed(ActionEvent e) {
        task.execute();
      }
    });

    JButton cancelButton = new JButton("Cancel");
    cancelButton.addActionListener(new ActionListener() {
      public void actionPerformed(ActionEvent e) {
        task.cancel(true);
      }
    });

    JPanel buttonPanel = new JPanel();
    buttonPanel.add(startButton);
    buttonPanel.add(cancelButton);

    JPanel cp = new JPanel();
    LayoutManager layout = new BoxLayout(cp, BoxLayout.Y_AXIS);
    cp.setLayout(layout);
    cp.add(buttonPanel);
    
    cp.add(progressBar);

    JFrame frame = new JFrame("SwingWorker Demo");
    frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
    frame.setContentPane(cp);
    frame.pack();
    frame.setVisible(true);
  }
}

class CounterTask extends SwingWorker<Integer, Integer> {
  @Override
  protected Integer doInBackground() throws Exception {
    int i = 0;
    int count = 10;
    while (!isCancelled() && i < count) {
      i++;
      publish(new Integer[] { i });
      setProgress(count * i / count);
      Thread.sleep(1000);
    }
    return count;
  }
  @Override
  protected void done() {
    if (isCancelled())
      System.out.println("Cancelled !");
    else
      System.out.println("Done !");
  }
}