How to calculate progress of Jprogressbar?

Question

Somehow the Jprogressbar is moving, but not in time with the code in the background method thru Swingworker. The task is done in another Thread, it works. I tried to use a while loop. println is not printing at the end. ? Thanks

// this is part of a time consuming task
for (int j = 0; j < ba.length; j++) {
    String s1 = Integer.toHexString((ba[j] & 255) | 256).substring(1);
    s2 += s1;
} // instead of the while loop, now is working a for loop.
 for(int z = 0; z <= 100; z++) {
  Thread.sleep(50);
  setProgress(z);
 }
 /*int z = 0;
 while(z <= 100) {
    z++;
    Thread.sleep(50);
    setProgress(z); */
}  
System.out.println(s2); 

here is the full example to execute.

import java.awt.*;
import java.awt.event.*;
import javax.swing.*;
import java.beans.*;
import java.io.FileInputStream;
import java.io.IOException;
import java.security.MessageDigest;
import java.security.NoSuchAlgorithmException;
import java.util.logging.Level;
import java.util.logging.Logger;

public class PbTest extends JPanel implements ActionListener, PropertyChangeListener {

    private JProgressBar progressBar;
    private JButton startButton;
    private JTextArea taskOutput;
    private Task task;
    private String nameString;
    private String s2;
    private int timeFlow;
    private boolean done;
    private int z = 0;

    class Task extends SwingWorker<Void, Void> {
        /*
         * Main task. Executed in background thread.
         */
        @Override
        public Void doInBackground() throws InterruptedException {

            done = false;

            try {
                FileInputStream fis = new FileInputStream("timeConsuming.iso");

                MessageDigest md = MessageDigest.getInstance("MD5");

                byte[] b = new byte[1024];
                int i;
                while ((i = fis.read(b)) >= 0) {
                    md.update(b, 0, i);
                }
                while (i != -1)
                    fis.close();
                byte[] ba = md.digest();
                // while loop correct?
                while (ba.length <= 16) {
                    int z = 0;
                    while (z <= 100) {
                        z++;
                        Thread.sleep(50);
                        setProgress(z);
                    }
                }
                // System.out.print(i);
                for (int j = 0; j < ba.length; j++) {
                    String s1 = Integer.toHexString((ba[j] & 255) | 256).substring(1);
                    s2 += s1;
                }
                System.out.println(s2);
            } catch (IOException | NoSuchAlgorithmException ex) {
                Logger.getLogger(PbTest.class.getName()).log(Level.SEVERE, null, ex);
            }
            return null;
        } // System.out.println(javax.swing.SwingUtilities.isEventDispatchThread());

        /*
         * Executed in event dispatching thread
         */
        @Override
        public void done() {
            Toolkit.getDefaultToolkit().beep();
            startButton.setEnabled(true);
            setCursor(null); // turn off the wait cursor
            taskOutput.append("Done!\n");
            done = true;
        }
    }

    public PbTest() {
        super(new BorderLayout());

        // Create the demo's UI.
        startButton = new JButton("Start");
        startButton.setActionCommand("start");
        startButton.addActionListener(this);

        progressBar = new JProgressBar(0, 100);
        // progressBar.setMinimum(0);
        // progressBar.setMaximum(100);
        progressBar.setValue(0);
        progressBar.setStringPainted(true);

        taskOutput = new JTextArea(5, 20);
        taskOutput.setMargin(new Insets(5, 5, 5, 5));
        taskOutput.setEditable(false);

        JPanel panel = new JPanel();
        panel.add(startButton);
        panel.add(progressBar);

        add(panel, BorderLayout.PAGE_START);
        add(new JScrollPane(taskOutput), BorderLayout.CENTER);
        setBorder(BorderFactory.createEmptyBorder(20, 20, 20, 20));

    }

    /**
     * Invoked when the user presses the start button.
     */
    public void actionPerformed(ActionEvent evt) {
        // progressBar.setIndeterminate(true);
        startButton.setEnabled(false);
        setCursor(Cursor.getPredefinedCursor(Cursor.WAIT_CURSOR));
        // Instances of javax.swing.SwingWorker are not reusuable, so
        // we create new instances as needed.
        task = new Task();
        task.addPropertyChangeListener(this);
        task.execute();
    }

    /**
     * Invoked when task's progress property changes.
     */
    public void propertyChange(PropertyChangeEvent evt) {
       //this code block would work better with more gui components ?!
       /*if ("progress".equals(evt.getPropertyName())) {
     int progress = (Integer) evt.getNewValue();
     progressBar.setValue(progress);
     ls.setText(String.format(
                "Completed %d%% of task.\n", task.getProgress()));
    } */
        if (!done) {
            int progress = task.getProgress();
            progressBar.setValue(progress);
            System.out.println(String.format("Completed %d%% of task.\n", task.getProgress()));
        }
    }

    /**
     * Create the GUI and show it. As with all GUI code, this must run on the
     * event-dispatching thread.
     */
    private static void createAndShowGUI() {
        // Create and set up the window.
        JFrame frame = new JFrame("ProgressBarDemo");
        frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);

        // Create and set up the content pane.
        JComponent newContentPane = new PbTest();
        newContentPane.setOpaque(true); // content panes must be opaque
        frame.setContentPane(newContentPane);

        // Display the window.
        frame.pack();
        frame.setVisible(true);
    }

    public static void main(String[] args) {
        // Schedule a job for the event-dispatching thread:
        // creating and showing this application's GUI.
        javax.swing.SwingUtilities.invokeLater(new Runnable() {
            public void run() {
                createAndShowGUI();
            }
        });
    }
}