// Getting fullscreen **effect** by extending the frame either direction.
frame.setExtendedState(JFrame.MAXIMIZED_BOTH);
frame.setUndecorated(true);frame.setExtendedState(JFrame.MAXIMIZED_BOTH);
frame.setUndecorated(true);
frame.setVisible(true);// For fullscreen, put the following in your code:
frame.setExtendedState(JFrame.MAXIMIZED_BOTH);
// You can also set the dimensions of the window like this:
frame.setSize(1920, 1080); // Change to resolution of your screen.GraphicsEnvironment graphics =
GraphicsEnvironment.getLocalGraphicsEnvironment();
GraphicsDevice device = graphics.getDefaultScreenDevice();
JFrame frame = new JFrame("Fullscreen");
device.setFullScreenWindow(frame);If you have extended the class to JFrame then -
this.setExtendedState(JFrame.MAXIMIZED_BOTH);
IF not then -
frame.setExtendedState(JFrame.MAXIMIZED_BOTH);