Answers for "set jframe full size"

java fullscreen jframe

frame.setExtendedState(JFrame.MAXIMIZED_BOTH);

set jframe fullscreen

GraphicsEnvironment graphics = 
		GraphicsEnvironment.getLocalGraphicsEnvironment();
        
GraphicsDevice device = graphics.getDefaultScreenDevice();
JFrame frame = new JFrame("Fullscreen");
device.setFullScreenWindow(frame);