[java] How to disable javax.swing.JButton in java?

I have created a swings application and there is a "Start" button on the GUI. I want that whenever I clicked on that "Start" button, the start button should be disabled and the "Stop" button be enabled.

For that I have written the following code in the "ActionPeformed(...)" method of the "Start" button

startButton.setEnabled(false);
stopButton.setEnabled(true);

But the above code is not creating the desired affect on the GUI.

Is the above code correct for what I want to do?

It's not working with "repaint()" too.

Edit:

The code is very long so I can't paste all the code. I can tell, though, more about the code.

In the "ActionPeformed" method of "start" button, after calling the above two statements, I am executing a "SwingWorker" thread.

Is this thread creating any problem?

This works.

public class TestButton {

public TestButton() {
    JFrame f = new JFrame();
    f.setSize(new Dimension(200,200));
    JPanel p = new JPanel();
    p.setLayout(new FlowLayout());

    final JButton stop = new JButton("Stop");
    final JButton start = new JButton("Start");
    p.add(start);
    p.add(stop);
    f.getContentPane().add(p);
    stop.setEnabled(false);
    stop.addActionListener(new ActionListener() {
        public void actionPerformed(ActionEvent e) {
            start.setEnabled(true);
            stop.setEnabled(false);

        }
    });

    start.addActionListener(new ActionListener() {
        public void actionPerformed(ActionEvent e) {
            start.setEnabled(false);
            stop.setEnabled(true);

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

/**
 * @param args
 */
public static void main(String[] args) {
    new TestButton();

}

}

The code is very long so I can't paste all the code.

There could be any number of reasons why your code doesn't work. Maybe you declared the button variables twice so you aren't actually changing enabling/disabling the button like you think you are. Maybe you are blocking the EDT.

You need to create a SSCCE to post on the forum.

So its up to you to isolate the problem. Start with a simple frame thas two buttons and see if your code works. Once you get that working, then try starting a Thread that simply sleeps for 10 seconds to see if it still works.

Learn how the basice work first before writing a 200 line program.

Learn how to do some basic debugging, we are not mind readers. We can't guess what silly mistake you are doing based on your verbal description of the problem.