Solved

Using setTitle() in modal JDialog

Posted on 2000-04-04
2
2,381 Views
Last Modified: 2012-05-04
In my "real" code, the first call to setTitle in a modal JDialog sets the title; then, future calls seem to have no effect.  Borrowing some code from a PAQ (thanks mjenkins!), I distilled it pretty well down (see below) - just switch the dialog from non-modal to modal to cause the problem.

Any clues?

I'm using JDK 1.2.2 on Windows NT 4.

Thanks in advance!

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

public class Title
        implements Runnable
{
        boolean b = true;
        private JDialog f;

        public static void main( String args[] )
        {
                Title foo = new Title();
                new Thread( foo ).start();
        }

        public Title()
        {
                f = new JDialog((Frame)null, false);  //works
                //f = new JDialog((Frame)null, true);  //does not work
        }

        public void run()
        {
                f.setSize( 400,400 );
                f.show();

                while( true )
                {
                        step();
                        try{
                        Thread.sleep(500);
                        }
                        catch( Exception e ) {}
                }
        }

        public void step()
        {
                  SwingUtilities.invokeLater(new Runnable()
                  {
                        public void run()
                        {
                b = !b;
                f.setTitle( b ? "True" : "False" );
                f.repaint(1);
                              
                        }
                  });
        }
}
0
Comment
Question by:azami
2 Comments
 
LVL 2

Accepted Solution

by:
stalefish earned 100 total points
ID: 2686133
I think a modal dialog holds a lock (of sorts) on the system. The whole idea behind a modal component is one that holds up the program until it is executed. You can see from the code I modified, that you can change the dialog from within.

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

public class Title /*implements Runnable*/ {
  private MyDialog f;

  public static void main( String args[] ) {
          Title foo = new Title();
         // new Thread( foo ).start();
  }

  public Title() {
          //f = new JDialog((Frame)null, false);  //works
          f = new MyDialog(null);  //does not work
  }
 }
      
class MyDialog extends JDialog implements Runnable{
  boolean b = true;
      Thread runner;
      public MyDialog(Frame owner){
            super(owner, true);
            runner = new Thread(this);
            runner.start();
            this.setSize( 400,400 );
    this.show();
      }
      
      public void run() {    
    while( true ){
           b = !b;
      this.setTitle( b ? "True" : "False" );
      this.repaint();

      try{ Thread.sleep(500); }
      catch( Exception e ) {}
    }
  }
 
}
0
 
LVL 1

Author Comment

by:azami
ID: 2687301
Yep, that sure 'nuff fixes the code.  Boy, is my face red... of course in my code the thread blocks when it calls f.show(), and doesn't reach the while loop until after the dialog is closed....

Turns out to not really be the problem I had, though - but it got me on the right track.  When trying to put together a new "simple" class that demonstrated my problem, I noticed that my code to change the title was only called once (in the constructor), so of course my title was never changing.

Guess that's what happens when working late at night...

Thanks!
0

Featured Post

Is Your Active Directory as Secure as You Think?

More than 75% of all records are compromised because of the loss or theft of a privileged credential. Experts have been exploring Active Directory infrastructure to identify key threats and establish best practices for keeping data safe. Attend this month’s webinar to learn more.

Question has a verified solution.

If you are experiencing a similar issue, please ask a related question

Suggested Solutions

Title # Comments Views Activity
Passing list of object to Oracle Database Procedure 3 59
Java array passed to SQL where clause 23 61
servlet  URL Rewriting 1 25
servlet filter example 37 34
For beginner Java programmers or at least those new to the Eclipse IDE, the following tutorial will show some (four) ways in which you can import your Java projects to your Eclipse workbench. Introduction While learning Java can be done with…
In this post we will learn how to connect and configure Android Device (Smartphone etc.) with Android Studio. After that we will run a simple Hello World Program.
Viewers will learn about if statements in Java and their use The if statement: The condition required to create an if statement: Variations of if statements: An example using if statements:
Viewers will learn about basic arrays, how to declare them, and how to use them. Introduction and definition: Declare an array and cover the syntax of declaring them: Initialize every index in the created array: Example/Features of a basic arr…

930 members asked questions and received personalized solutions in the past 7 days.

Join the community of 500,000 technology professionals and ask your questions.

Join & Ask a Question

Need Help in Real-Time?

Connect with top rated Experts

16 Experts available now in Live!

Get 1:1 Help Now