Java JFrame not updating settings of a button

Question

I am currently having a minor issue with a Java Jframe and a button not updating.

I am trying to disable the Print Button until the printing of the new JFrame it opens is done and that JFrame is closed...

The button will only disable if and when a new window occurs, but will not until then, which can take a little bit of time....

I set the button to disable by doing this: PrintBttn.setEnabled(false);

I have tried calling mainPanel.revalidate(); mainPanel.repaint(); PrintBttn.revalidate(); PrintBttn.repaint as well as a mixture of the above as they recommended in other forums...

I am kind of lost at the moment on this and to why it is not disabling the button until a new window appears since the first thing i do is Disable it as shown above, and then go through and create the new window....

Thanks, Erik

Answer 1

Most likely, it's a question of releasing the EDT to allow it to repaint the disabled button.

Generally, it will look something like this:

PrintBttn.setEnabled(false);
SwingUtilities.invokeLater(new Runnable() {
    public void run() {
        // Code to display the second JFrame goes here
    }
};

Answer 2

Might be you had failed to put your first frame in the EDT too, do watch the code, is this what you actually want :

import java.awt.event.*;

import javax.swing.*;

public class TwoFrames
{
    private JFrame frame1, frame2;
    private JPanel panel1, panel2;
    private JButton button1, button2, button3;
    private ActionListener action;

    public TwoFrames()
    {               
        frame1 = new JFrame("Frame One");
        frame1.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);

        frame2 = new JFrame("Frame Two");
        frame2.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);

        panel1 = new JPanel();      

        action = new ActionListener()
        {
            public void actionPerformed(ActionEvent ae)
            {
                if (ae.getSource() == button1)
                {
                    // Here goes your code for displaying your Second Frame.
                    SwingUtilities.invokeLater(new Runnable()
                    {
                        public void run()
                        {
                            if (!frame2.isShowing())
                            {                                                           
                                panel2 = new JPanel();

                                button2 = new JButton("Click Me to HIDE FRAME.");
                                button2.setHorizontalTextPosition(AbstractButton.CENTER);
                                button2.setVerticalTextPosition(AbstractButton.CENTER);
                                button2.addActionListener(action);

                                panel2.add(button2);
                                panel2.setOpaque(true);
                                frame2.setContentPane(panel2);

                                frame2.setSize(200, 200);
                                frame2.setLocationRelativeTo(null);
                                frame2.setVisible(true);
                            }
                        }
                    });             
                    button3.setEnabled(false);
                }
                else if (ae.getSource() == button2)
                {
                    frame2.dispose();
                    button3.setEnabled(true);
                }
            }       
        };

        button1 = new JButton("Click Me to Display FRAME.");
        button1.setHorizontalTextPosition(AbstractButton.CENTER);
        button1.setVerticalTextPosition(AbstractButton.CENTER);
        button1.addActionListener(action);          

        button3 = new JButton("Watch Me getting DISABLED");
        button3.setHorizontalTextPosition(AbstractButton.CENTER);
        button3.setVerticalTextPosition(AbstractButton.CENTER);
        button3.addActionListener(action);

        panel1.add(button1);
        panel1.add(button3);
        panel1.setOpaque(true);
        frame1.setContentPane(panel1);      

        frame1.setSize(200, 200);       

        frame1.setVisible(true);
    }

    public static void main(String... args)
    {
        // Here we are Scheducling a JOB for Event Dispatcher Thread.
        SwingUtilities.invokeLater(new Runnable()
        {
            public void run()               
            {
                new TwoFrames();
            }
        });
    }
}