JProgressBar and ObserverPattern in multiple document app??

Question

Hi,
I'm working on a multiple document application with jInternalFrames. There is one very time-consuming process and therefore I'd like to show a progressbar for the user to know, that the programm is still running.
So Icreated a seperate internalFrame with a jProgressBar and I implemented the observer pattern.
Now the problem is: my time-consuming process (which is in the observable-class) notifies the internalFrame whenever one percent of work is done,
and the programm even enters the update method of the internal frame. In this update method i set the value of the
progress bar, but nothing happens. I tried a repaint() and even a paintImmediately() but nothing happens until
my time-consuming process is done. That's not exactly what i call a progressbar... ;-) It is even worse as the whole view of the application is faulty once I minimized and then resized the main window while my time-consuming process is running.
So I already found some articles and I fear I have to work with threads. But how?
can anyone explain to me what method I have to run as a thread and how can I refresh my internalFrame respectively the progressbar then?
I hope anyone can help me...

Answer 1

* Progress_Test.java
import java.awt.*;
import java.awt.event.*;
import javax.swing.*;
public class Progress_Test extends JFrame {
    public Progress_Test() {
        initComponents();
    private void initComponents() {
        desktop = new JDesktopPane();
        internalFrame = new JInternalFrame();
        panel = new JPanel();
        progressBar = new JProgressBar();
        progressBar.setVisible(false);
        toolbar = new JToolBar();
        startBtn = new JButton();
        setDefaultCloseOperation(WindowConstants.EXIT_ON_CLOSE);
        setTitle("Test Progress");
        internalFrame.setPreferredSize(new Dimension(200, 100));
        internalFrame.setVisible(true);
        panel.add(progressBar);
        internalFrame.getContentPane().add(panel, BorderLayout.CENTER);
        startBtn.setText("Start");
        startBtn.addActionListener(new ActionListener() {
            public void actionPerformed(ActionEvent evt) {
                startBtnActionPerformed(evt);
        toolbar.add(startBtn);
        internalFrame.getContentPane().add(toolbar, BorderLayout.NORTH);
        internalFrame.setBounds(0, 0, 200, 100);
        desktop.add(internalFrame, JLayeredPane.DEFAULT_LAYER);
        getContentPane().add(desktop, BorderLayout.CENTER);
        Dimension screenSize = Toolkit.getDefaultToolkit().getScreenSize();
        setBounds((screenSize.width-400)/2, (screenSize.height-300)/2, 400, 300);
    private void startBtnActionPerformed(ActionEvent evt) {
        if( ltThread == null || !ltThread.isAlive() ){
            progressBar.setValue(0);
            LongTask lt = new LongTask();
            ltThread = new Thread(lt);
            ltThread.start();
    public static void main(String args[]) {
        new Progress_Test().setVisible(true);
    private JDesktopPane desktop;
    private JInternalFrame internalFrame;
    private JPanel panel;
    private JProgressBar progressBar;
    private JButton startBtn;
    private JToolBar toolbar;
    private Thread ltThread;
    public class LongTask implements Runnable{
        public LongTask() {
            progressBar.setMaximum(max);
        public void run(){
            progressBar.setVisible(true);
            int n=0;
            while ( n<max ){
                n++;
                progressBar.setValue(n);
                try{Thread.sleep(1000);}catch(Exception ex){}
            progressBar.setVisible(false);
        private int max=10;
}