In my Swing application, I want the ability to switch between decorated and undecorated without recreating the entire frame. However, the API doesn't let me call setUndecorated() after the frame is made visible.
Even if i call setVisible(false), isDisplayable() still returns true. The API says the only way to make a frame not-displayable is to re-create it. However, I don't want to recreate the frame just to switch off some title bars.
I am making a full-screenable application that can be switched between fullscreen and windowed modes; It should be able to switch while maintaining the state, etc.
How do I do this after a frame is visible?.
You can't. That's been my experience when I tried to achieve the same.
However if you have your entire UI in one panel which is in your frame, you can create a new frame and add that panel to the frame. Not so much work.
Something like this:
// to start with
JPanel myUI = createUIPanel();
JFrame frame = new JFrame();
frame.add(myUI);
// .. and later ...
JFrame newFrame = new JFrame();
newFrame.setUndecorated();
newFrame.add(myUI);
In Swing a panel (and indeed any instance of a component) can only be in one frame at a time, so when you add it to a new frame, it immediately ceases to be in the old frame.