Re: Java UI Hanging with wait()

From:
Knute Johnson <nospam@rabbitbrush.frazmtn.com>
Newsgroups:
comp.lang.java.programmer
Date:
Mon, 17 Mar 2008 14:11:20 -0700
Message-ID:
<47dede78$0$1587$b9f67a60@news.newsdemon.com>
ash wrote:

You are blocking the Event Dispatch Thread. Nothing GUI related will
work while its thread is asleep.

If you need to do two things at different times to your GUI, run another
thread that calls the actions on the GUI in the EDT using
EventQueue.invokeLater().


I created a thread that is passed the components that will be modified
in the GUI and its run() it modified it.

 That thread is called by EventQueue.invokeLater() method from the
synchronized method. It still didnt work , it did the same behaviour
exactly. I suspect i am doing it incorrectly. if you would point out
whats done incorrectly i would greatly appreciate it.


Here is a simple example you can try.

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

class test7 {
     public static void main(String[] args) {
         EventQueue.invokeLater(new Runnable() {
             public void run() {
                 JFrame f = new JFrame();
                 f.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
                 f.setLayout(new GridBagLayout());
                 GridBagConstraints c = new GridBagConstraints();

                 c.gridx = 1;
                 final JLabel l = new JLabel("Button Not Yet Pressed");
                 f.add(l,c);

                 final JButton b = new JButton("Start");
                 b.addActionListener(new ActionListener() {
                     public void actionPerformed(ActionEvent ae) {
                         b.setEnabled(false);
                         l.setText("Running");
                         Runnable r = new Runnable() {
                             public void run() {
                                 try {
                                     Thread.sleep(5000);
                                 } catch (InterruptedException ie) {
                                     ie.printStackTrace();
                                 }
                                 EventQueue.invokeLater(new Runnable() {
                                     public void run() {
                                         b.setEnabled(true);
                                         l.setText("Done");
                                     }
                                 });
                             }
                         };
                         new Thread(r).start();
                     }
                 });
                 f.add(b,c);

                 f.pack();
                 f.setVisible(true);
             }
         });
     }
}

--

Knute Johnson
email s/nospam/linux/

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