Threads + Swing = Confusion

Question

Hi all,
I am having a problem with threads and Swing apps. I have read the tutorial 3 times and get more confused each time i try to understand how to update the gui with the other thread.
At this point I'm just trying to do something simple (eventually i want the gui to report all the progress of the action): get a progress bar to be updated through a Thread Class. I have the gui built with a button and a progress bar. Here is the codei have for the simpleThread class
import java.awt.*;
import javax.swing.*;
public class simpleThread extends Thread{
    public simpleThread(String str) {
        super(str);
    public void run() {
        for (int i = 0; i<1000000; i++) {
            final int x = i;
            Runnable getTextFieldText = new Runnable() {
                public void run() {
                   jProgressBar1.setValue(x);
    SwingUtilities.invokeAndWait(getTextFieldText);
}The problem i have is that the thread doesn't recognize the gui form. Any help on getting the progress bar to update with the thread would be great! Thanks! :)

Answer 1

There's been too much bad code submitted to this topic to comment on it individually, but:
1. Don't call a thread or runnable's run() method directly, if you expect it to be executed in a different thread! Call thread's start method instead.
2. If you want code executed in the Event Dispatch Thread (EDT), pass a runnable to InvokeLater (usually preferrable to InvokeAndWait). That runnable's run method will be executed in the EDT -- there's no need to write complicated nested run methods!
In the case of JProgressBar, I was concerned about flooding the EDT with many "invokeLater" runnables, so I penned this wee class:
import javax.swing.*;
public class Updater  {
     private final JProgressBar jpb;
     private boolean queued;
     private int val;
     private Runnable runnable = new Runnable() {
          public void run() {//called from EDT:
               int _val;
               synchronized(Updater.this) {
                    queued = false;
                    _val = val;
               jpb.setValue(_val);
     public Updater(JProgressBar jpb) {
          this.jpb = jpb;
     public void update(int _val) {
          boolean go = false;
          synchronized(this) {
               val = _val;
               if (!queued) {
                    queued = true;
                    go = true;
          if (go)
               SwingUtilities.invokeLater(runnable);
}To use it, you would typically declare it as a field:
private Updater updater = new Updater(yerBar);Then repeatedly call (from any thread)
updater.update(yerValue);