Problems with updating the text of a JButton...!!

[Parth Bhatt]

Hello guys,
i am on a project that involves updating the text of a JButton while the application is running...!! Here's my code snippet that has an actionPerformed method where this is to be done.

In the following code snippet
SearchButton is the instance of JButton, which when clicked should start searching.

  
    public void actionPerformed(ActionEvent actionevent)
    {
        String s = actionevent.getActionCommand();
 
        if(s.equals("Search"))
        {
            SearchButton.setText("Stop"); // CHANGE THE TEXT OF THE SEARCH BUTTON TO "STOP" BEFORE CALLING THE SEARCH ROUTINE
            Status.setText("0");
 
            /*SPAWN A THREAD FOR EACH DRIVE IN THE SYSTEM*/
            BrowserThread abrowserthread[] = new BrowserThread[10];
            File file = new File("/");
            File _tmp = file;
            File afile[] = File.listRoots();
 
            for(int i = 0; i < afile.length; i++)
            {
                abrowserthread[i] = new BrowserThread(afile[i].toString(), SearchQuery.getText());
                /*START SEARCHING*/
                abrowserthread[i].start();
            }
        }
        if(s.equals("Search"))
        {
 
            SearchButton.setText("Search");
        }
    }

The problem is that the text of SearchButton is not getting updated till all the statements in the if(s.equals("Search")) block get executed

Please comment...

[Dan Patterson]

Someone may have a better idea, but you could try this. Put a yield() after the text change.

  
public void actionPerformed(ActionEvent actionevent)
    {
        String s = actionevent.getActionCommand();
 
        if(s.equals("Search"))
        {
            SearchButton.setText("Stop"); // CHANGE THE TEXT OF THE SEARCH BUTTON TO "STOP" BEFORE CALLING THE SEARCH ROUTINE
            [B]yield();[/B]
            Status.setText("0");
 
            /*SPAWN A THREAD FOR EACH DRIVE IN THE SYSTEM*/
            BrowserThread abrowserthread[] = new BrowserThread[10];
            File file = new File("/");
            File _tmp = file;
            File afile[] = File.listRoots();
 
            for(int i = 0; i < afile.length; i++)
            {
                abrowserthread[i] = new BrowserThread(afile[i].toString(), SearchQuery.getText());
                /*START SEARCHING*/
                abrowserthread[i].start();
            }
        }
        if(s.equals("Search"))
        {
 
            SearchButton.setText("Search");
        }
    }   

[Parth Bhatt]

hii dan !!
The yield() method makes no difference...!! i've tried using it as

   Thread.yield();   

as yield() is a static method... but this makes absolutely no difference...!!

Any more comments plz....!!

[Craig Wood]

For information about the event dispatch thread and using threads in Swing see How to Use Threads.

import java.awt.*;
import java.awt.event.*;
import javax.swing.*;
 
public class UIUpdate implements ActionListener, Runnable
{
    JButton SearchButton;
    Thread thread;
    boolean pressOn = false;
 
    public void actionPerformed(ActionEvent actionevent)
    {
        String s = actionevent.getActionCommand();
        System.out.println("s = " + s);
 
        if(s.equals("Search"))
        {
            // CHANGE THE TEXT OF THE SEARCH BUTTON TO "STOP"
            // BEFORE CALLING THE SEARCH ROUTINE
            SearchButton.setText("Stop");
            SearchButton.setActionCommand("Stop");
 
            /*SPAWN A THREAD FOR EACH DRIVE IN THE SYSTEM*/
            // two options:
            // 1 - start a new thread to do the slow work in the
            //     background and allow the gui to remain responsive
            start();
 
            //      --- or ---
 
            // 2 - do it on the event dispatch thread which will
            //     freeze up the gui until this method returns
//            tieUpEventDispatchThread();
        }
        if(s.equals("Stop"))
        {
            pressOn = false;
            if(thread != null) // guard for tieUpEventDispatchThread
            {
                thread.interrupt();
                thread = null;
            }
            SearchButton.setText("Search");
            SearchButton.setActionCommand("Search");
        }
    }
 
    public void run()
    {
        int count = 0;
        while(count++ < 10 && pressOn)
        {
            try
            {
                Thread.sleep(1000);
            }
            catch(InterruptedException ie)
            {
                System.err.println("interrupt: " + ie.getMessage());
            }
            System.out.println("count = " + count);
        }
        SearchButton.setText("Search");
        SearchButton.setActionCommand("Search");
    }
 
    private void start()
    {
        if(!pressOn)
        {
            pressOn = true;
            thread = new Thread(this);
            thread.setPriority(Thread.NORM_PRIORITY);
            thread.start();
        }
    }
 
    private void tieUpEventDispatchThread()
    {
        for(int j = 0; j < 5; j++)
        {
            try
            {
                Thread.sleep(1000);
            }
            catch(InterruptedException ie)
            {
                System.err.println("interrupt: " + ie.getMessage());
            }
            System.out.println("j = " + j);
        }
    }
 
    private JPanel getContent()
    {
        SearchButton = new JButton("Searching");
        SearchButton.setActionCommand("Search");
        SearchButton.addActionListener(this);
        JPanel panel = new JPanel();
        panel.add(SearchButton);
        return panel;
    }
 
    public static void main(String[] args)
    {
        UIUpdate uiu = new UIUpdate();
        JFrame f = new JFrame();
        f.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
        f.getContentPane().add(uiu.getContent(), "North");
        f.setSize(300,300);
        f.setLocation(200,200);
        f.setVisible(true);
    }
}

[Parth Bhatt]

Hey !!

Thanks a lot Craig, you're a "rock star" !! got my solution...!!

Thanks Dan 4 de help...!!
[ March 16, 2006: Message edited by: Parth Bhatt ]