Java - how to make "runnable" JTable?

Question

Hello, I have problem creating JTable, which will show every second some text. I make MainView, place JTable and have Class "TableHandler(JTable table) implements Runnable" which is supposed to add some text in intervals to JTable ... Here is run method :

public void run() {
    for (int i=0; i<5; i++) {
        table.setValueAt("text", i, i);
        try {
            Thread.sleep(1000);
        } catch (InterruptedException ex) {
            ex.printStackTrace();
        }
    }
}

The problem is, that MainView wont "show" until Jtable is filled with data, so user doesn't see filling :-(

EDIT : more code

public MyView(SingleFrameApplication app) {
    super(app);

    initComponents();
    // log of GUI stuff here
   TableHandler th = new TableHandler(myTable);
   th.createTable(); // just loads data
   Timer t = new Timer(100,new ActionListener() {
   public void actionPerformed(ActionEvent e) {
       th.run();
      }
   });
   t.start();

Answer 1

Try putting a call to repaint after your setValueAt() call. Preferably wrapped in SwingUtilities.invokeLater.

Answer 2

The mostly likely problem to the behavior you are describing is that you aren't using a separate thread to start the run method. If the run method is called directly then the screen will not update until the main thread is available again, which will not occur until after the run method completes.

Verify that you are not calling run() anywhere in your code as that should be handled in the thread.

EDIT: The code to start the class should look something like this:

new Thread(new TableHandler(table)).start();

Answer 3

You must use SwingUtilities.invokeLater if you are running it in a thread.

This will just queue up requests to your painting routine, so then you need to be sure they are called by putting a pause. It should look something like this:

in your main--or somewhere equivilent:
    new myThread
    myThread.start()

myThread.run()
   new myRoutine();
   while(activelyUpdating)
       invokeLater(myRoutine);
       sleep(something reasonable, like 1000 for updates every second);


myRoutine
    do all your drawing crap
    return (do not loop here, that's done in the thread.  Just return)

There is probably a way to have your sleep wait until the invokeLater queue is empty, but be sure you sleep as well because otherwise the AWT thread (the thread "myRoutine" will run on) will never get a chance to run and invokeLater threads will just queue up.

Answer 4

If you are using Swing and want to perform an action on a time interval, you should use a swing timer, as described in the tutorial.

Translating your loop into a sequence of calls to actionPerformed, you get:

    new Timer ( 1000, new ActionListener () {
        int i = 0; // moved out of loop 

        @Override
        public void actionPerformed ( ActionEvent event ) {
            if ( i < 5 ) {
                i++;

                table.setValueAt ( "text", i, i );

            } else {
                // stop the timer firing events when the loop end 
                // condition is reached
                ( ( Timer ) event.getSource() ).setRepeats ( false );
            }
        }
    } ).start();

Answer 5

As per you comments.

Call start not run as mmyers points, using the former is the correct.

So it should be:

Thread t = new Thread( this.table ); // or new Thread( this )

t.start(); // call start on the read 

and not

this.table.run();

or

t.run();

Answer 6

You need to update from the AWT thread:

public void run() {
    for (int i=0; i<5; i++) {
        final int x = i;
        SwingUtilities.invokeLater( new Runnable() {
          public void run() {
            table.setValueAt("text", x, x);
           }});
        try {
            Thread.sleep(1000);
        } catch (InterruptedException ex) {
            ex.printStackTrace();
        }
    }
}

See http://java.sun.com/javase/6/docs/api/javax/swing/SwingUtilities.html#invokeLater(java.lang.Runnable)