Java - is there a way to hide the close button in a swing application?

Question

is there a way to hide the close button in a swing application?

I know I can set JFrame.DO_NOTHING_ON_CLOSE but is there a way to eliminate it completely?

if I write setUndecorated(true) I get
IllegalComponentStateException - the frame is displayable

Answer 1

Using frame.setUndecorated(true) while the frame has already been displayed leads to an error as this is not allowed in the API . Instead, use frame.setUndecorated(true) before you set frame.setVisible(true) . This should solve your error:

IllegalComponentStateException - the frame is displayable

If you are successful, the close button will be hidden.