Progress Bar Thread Java

rebellad

I am trying to get a progress bar going so that it shows the app is doing something while I am processing a file in the background. I have had a read up on it and according to the net the easiest way to do it is to create a thread which will run the progress bar. I am fine with all this but when I run my code the progress bar appears but doesn't update, I have put a println in the code for the progress bar and it appears to process the code for it alright but for some reason it won't update the progress bar. When the file is finished processing the progress bar updates to 100% in one go. Anyone got any ideas??

Anima

Post the code up, make it easier to debug.

Kevo

Did you call jpanel.updateUI()?

NotMe

Are you using JProgressBar?

rebellad

Here is the code guys :

Calling code :

ClsProgressMonitor t = new ClsProgressMonitor();
Thread th = new Thread(t);
th.start();


ClsProgressMonitor

package ie.xxx.retail.YYYYY;

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

public class ClsProgressMonitor implements Runnable {

static JProgressBar jpb;
static ClsProgressMonitor _this;

public ClsProgressMonitor (){
_this = this;
}

public static void createAndShowGUI(){
JFrame aFrame = new JFrame("Swing Thread Example: Fixed Threading");
JButton aButton = new JButton("Do Something");
//aFrame.getContentPane().add(aButton, BorderLayout.SOUTH);
//aButton.addActionListener(_this);
JPanel aPanel = new JPanel();
aPanel.add(new JLabel("Progress:"));
jpb = new JProgressBar(0,100);
aPanel.add(jpb);
aFrame.getContentPane().add(aPanel);
aFrame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
aFrame.pack();
aFrame.setVisible(true);

}



// worker thread
public void run(){
createAndShowGUI();
while(true){
// wait for the signal from the GUI
//try{synchronized(this){wait();}}
// catch (InterruptedException e){}
// simulate some long-running process like parsing a large file
for (int i = 0; i <= 100; i++){
jpb.setValue(i);
jpb.updateUI();
System.out.println("actionPerformed sets jpb value to: "+i);
try{Thread.sleep(50);} // make the process last a while
catch (InterruptedException e){}
}
break;
}
}
}

itscout

When running your example the progress bar updates fine, incrementally, not all in one go - isn't the same for you with this exact code snippet ?

In this snippet you simulate I/O by doing

rebellad wrote: »

Here is the code guys :
for (int i = 0; i <= 100; i++){
.....
try{Thread.sleep(50);} // make the process last a while
catch (InterruptedException e){}
}
.....
}

Is your real code splitting the I/O operations in 100 roughly equivalent sub-operations and after each one you call "jpb.setValue(i); " ?

Maybe this snippet doesn't closely replicate your real usecase ?
In this code I see no reason for a separate thread. The "IO" and GUI updates are happening in the same thread
--
IT Scout - www.jobscout.ie

rebellad

Thanks ITScout, yeah if I run that code on it's own there is no problem. But in my app code what I am doing is reading info from a file in another class so I call

ClsProgressMonitor t = new ClsProgressMonitor();
Thread th = new Thread(t);
th.start();

to run the progress bar while the main app reads in the file. It is really strange because no matter what I do the progress bar will not update until the main app is finished processing. It shows the blank jframe that the progress bar is on but the progress bar doesn't show until the main app is finished

itscout

rebellad wrote: »

Thanks ITScout, yeah if I run that code on it's own there is no problem. But in my app code what I am doing is reading info from a file in another class so I call

ClsProgressMonitor t = new ClsProgressMonitor();
Thread th = new Thread(t);
th.start();

to run the progress bar while the main app reads in the file.

I'm afraid it's hard to help without the actual code. It would be much easier to first be able to replicate your problem and then figure it out.

The main question is which thread and when triggers the progress bar update in your real code.
--
IT Scout - www.jobscout.ie

JC 2K3

Try calling repaint () at the end of run ()?

See what happens if you don't use the sleep, also.

sh_o

It has been a long time since I touched swing, but iirc there is the swingutilities class which handle some of the threads in a swing gui. google for concurrency and swing or invokeLater and that may help.