What is the difference between a JFrame and a JDialog?

Question

What is the difference between a JFrame and a JDialog?

Why can\'t we use setDefaultCloseOperation(JDialog.EXIT_ON_CLOSE); for a JD

Answer 1

Why we can't use setDefaultCloseOperation(JDialog.HIDE_ON_CLOSE); for JDialog?

Sure you can.

Post your SSCCE that demonstrates the problem you are having when using this value.

However you can't use EXIT_ON_CLOSE for a JDialog because that value is not supported which makes sense since a JDialog is a "child" or "helper" window for your application which is represented by a JFrame. Closing a dialog should not close the application.