// Uses a JProgressBar

import java.awt.*;
import java.awt.event.*;
import javax.swing.*;

public class JProgressBarApp extends JPanel
                             implements Runnable
{
  // 1. Create a JProgressBar and a JButton
  JProgressBar bar = new JProgressBar();
  JButton      btn = new JButton("Start");

  public JProgressBarApp()
  {
    setLayout(new BorderLayout());

    // 2. Initialize the JProgressBar, add to App
    bar.setBorderPainted(true);
    bar.setStringPainted(true);
    bar.setValue(0);
    add(bar, BorderLayout.NORTH);

    // 3. Add JButton to south in FlowLayout panel
    JPanel p = new JPanel(
               new FlowLayout(FlowLayout.CENTER));
    p.add(btn);
    add(p, BorderLayout.SOUTH);

    // 4. Start a new task when Start button pressed
    btn.addActionListener(new ActionListener()
    {
      public void actionPerformed(ActionEvent ae)
      {
        new Thread(JProgressBarApp.this).start();
      }
    });
  }

  // Task when Start button is pressed
  public void run()
  {
    // 1. Disable the Start button
    btn.setEnabled(false);

    // 2. Choose a random job length
    int jobLength = (int)(Math.random() * 1000) + 100;

    // 3. Initialize the JProgressBar
    bar.setMaximum(jobLength);  // How long is the job?
    bar.setString(null);        // Display % while painting
    bar.setValue(0);            // Start at 0

    for (int i = 0; i < jobLength; i++)
    {
      // 4. After each "chunk", update the progress bar
      bar.setValue(i);

      try { Thread.sleep(10); }
      catch (InterruptedException ie) { }
    }
    
    // 5. Change the string displayed in the progress bar
    bar.setValue(jobLength);
    bar.setString("Job Finished");

    // 6. Reset the Start button
    btn.setEnabled(true);
  }

  public static void main(String[] args)
  {
    new GApp("The JProgressBar Application",
      new JProgressBarApp()).show();
  }
}