set jframe full size code example
Example 1: java fullscreen jframe
frame.setExtendedState(JFrame.MAXIMIZED_BOTH);
Example 2: set jframe fullscreen
GraphicsEnvironment graphics =
GraphicsEnvironment.getLocalGraphicsEnvironment();
GraphicsDevice device = graphics.getDefaultScreenDevice();
JFrame frame = new JFrame("Fullscreen");
device.setFullScreenWindow(frame);