I've seen posts talking about this in the past but no body has ever
acknowledged a bug or proposed a solution.  What gives?

If you try to download a file from a website in a Java Swing app, the
file comes down but the progress bar doesn't show.  Try the two code
examples below and see.  The first one requires a url to some large
file on the web.  The second requires a large file (update.zip) in the
working directory.

No progress bar here...

import java.awt.FlowLayout;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import java.io.FileInputStream;
import java.io.InputStream;
import java.net.*;

import javax.swing.JButton;
import javax.swing.JFrame;
import javax.swing.ProgressMonitorInputStream;

public class Test {
 public static void main(String[] args) {
   // create a test frame with a "press me" button
   final JFrame f = new JFrame("Sample");
   f.getContentPane().setLayout(new FlowLayout());
   JButton b = new JButton("Press me");
   f.getContentPane().add(b);
   f.pack();

   // set up the file read action
   b.addActionListener(new ActionListener() {
     public void actionPerformed(ActionEvent e) {
       // when button is pressed, start a new thread
       //   to read the file. A new thread is needed because we
       //   need to free the GUI update thread to paint the
       //   progress monitor
       new Thread() {
         public void run() {
           try {
             // open the file, wrapping it in a
ProgressMonitorInputStream
             InputStream in = new URL("http://some big web
file").openStream();
             ProgressMonitorInputStream pm =
                 new ProgressMonitorInputStream(f,"Reading the big
file",in);
             // read the file. If it's taking too long, the progress
             //   monitor will appear. The amount of time is roughly
             //   1/100th of the estimated read time (based on how
long
             //   it took to read the first 1/100th of the file.)
             //   Note that by default, the dialog won't appear
unless
             //   the overall estimate is over 2 seconds.
             int c;
             while((c=pm.read()) != -1) {
               // do something
             }
             pm.close(); // needs better error handling, of course...
           }
           catch(Exception ex) {
             ex.printStackTrace();
           }
         }
       }.start();
     }});  
 
   // display the frame
   f.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
   f.setVisible(true);
 }
}

Progress bar shows here...

import java.awt.FlowLayout;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import java.io.FileInputStream;
import java.io.InputStream;

import javax.swing.JButton;
import javax.swing.JFrame;
import javax.swing.ProgressMonitorInputStream;

public class Test {
 public static void main(String[] args) {
   // create a test frame with a "press me" button
   final JFrame f = new JFrame("Sample");
   f.getContentPane().setLayout(new FlowLayout());
   JButton b = new JButton("Press me");
   f.getContentPane().add(b);
   f.pack();

   // set up the file read action
   b.addActionListener(new ActionListener() {
     public void actionPerformed(ActionEvent e) {
       // when button is pressed, start a new thread
       //   to read the file. A new thread is needed because we
       //   need to free the GUI update thread to paint the
       //   progress monitor
       new Thread() {
         public void run() {
           try {
             // open the file, wrapping it in a
ProgressMonitorInputStream
             InputStream in = new FileInputStream("update.zip");
             ProgressMonitorInputStream pm =
                 new ProgressMonitorInputStream(f,"Reading the big
file",in);
             // read the file. If it's taking too long, the progress
             //   monitor will appear. The amount of time is roughly
             //   1/100th of the estimated read time (based on how
long
             //   it took to read the first 1/100th of the file.)
             //   Note that by default, the dialog won't appear
unless
             //   the overall estimate is over 2 seconds.
             int c;
             while((c=pm.read()) != -1) {
               // do something
             }
             pm.close(); // needs better error handling, of course...
           }
           catch(Exception ex) {
             ex.printStackTrace();
           }
         }
       }.start();
     }});  
 
   // display the frame
   f.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
   f.setVisible(true);
 }
}