What is the difference between a JFrame and a JDia

问题:

What is the difference between a JFrame and a JDialog?

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

回答1:

JFrame is a normal window with its normal buttons (optionally) and decorations. JDialog on the other side does not have a maximize and minimize buttons and usually are created with JOptionPane static methods, and are better fit to make them modal (they block other components until they are closed).

But both inherit from Window, so they share much functionality.

回答2:

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.

回答3:

There are some JDialog constructors with a owner parameter which can be a Frame, a Dialog or a Window. A non-null value also makes the JDialog stay above his owner. This is complementary of the modal behavior described by Fortran.

回答4:

You can also use setModal(boolean t); This only works on JDialog. User must operate on JDialog not other window. If they wanna operate owner windows, they must shut down this JDialog.