How to make main window inactive after error JFrame pops

Question

So I have a main frame that sometimes produces an error frame by pressing on one of the JButtons. I want to make it so when the error frame pops, main frame is inactive and you are unable to press any buttons. Is there an easy way for that?

Answer 1

What you are referring to is modality¹, for which case a modal JDialog is more appropriate than a JFrame. See more at How to Use Dialogs

Also, if this is a simple message popup, a simple JOptionPane would be more suitable. You can also see how to use JOptionPanes in the link above.

Here's a simple JOPtionPane example. Though I don't use a frame in the example, if you do have a frame, the JOptionPane will block any user interaction.

import javax.swing.JOptionPane;
public class SimpleErrorMessage {
    public static void main(String[] args) {
       JOptionPane.showMessageDialog(
               null, "Error!", "Error Message", JOptionPane.ERROR_MESSAGE);
    }  
}

• See JOptionPane API for more dialog options.

_{1. A dialog box can be either modeless or modal. A modal dialog box is one that blocks input to some other top-level windows in the application, except for any windows created with the dialog box as their owner. The modal dialog box captures the window focus until it is closed, usually in response to a button press}

Answer 2

You can use a glass pane to make main frame "inactive": http://docs.oracle.com/javase/tutorial/uiswing/components/rootpane.html