JFrame in full screen Java

Question

Add:

frame.setExtendedState(JFrame.MAXIMIZED_BOTH); 
frame.setUndecorated(true);
frame.setVisible(true);

If you want put your frame in full-screen mode (like a movie in full-screen), check these answers.

• How can I do full screen in Java on OSX
• Java setFullScreenWindow() keep on top

The classes java.awt.GraphicsEnvironment and java.awt.GraphicsDevice are used for put an app in full-screen mode on the one screen (the dispositive).

e.g.:

static GraphicsDevice device = GraphicsEnvironment
        .getLocalGraphicsEnvironment().getScreenDevices()[0];

public static void main(String[] args) {

    final JFrame frame = new JFrame("Display Mode");
    frame.setDefaultCloseOperation(WindowConstants.EXIT_ON_CLOSE);
    frame.setUndecorated(true);

    JButton btn1 = new JButton("Full-Screen");
    btn1.addActionListener(new ActionListener() {
        @Override
        public void actionPerformed(ActionEvent e) {
            device.setFullScreenWindow(frame);
        }
    });
    JButton btn2 = new JButton("Normal");
    btn2.addActionListener(new ActionListener() {
        @Override
        public void actionPerformed(ActionEvent e) {
            device.setFullScreenWindow(null);
        }
    });

    JPanel panel = new JPanel(new FlowLayout(FlowLayout.CENTER));
    panel.add(btn1);
    panel.add(btn2);
    frame.add(panel);

    frame.pack();
    frame.setVisible(true);

}

Use setExtendedState(int state), where state would be JFrame.MAXIMIZED_BOTH.

One way is to use the Extended State. This asks the underlying OS to maximize the JFrame.

setExtendedState(getExtendedState() | JFrame.MAXIMIZED_BOTH);

Other approach would be to manually maximize the screen for you requirement.

Dimension dim = Toolkit.getDefaultToolkit().getScreenSize();
setBounds(100, 100, (int) dim.getWidth(), (int) dim.getHeight());
setLocationRelativeTo(null);

But this has pitfalls in Ubuntu OS. The work around I found was this.

if (SystemHelper.isUnix()) {
    getContentPane().setPreferredSize(
    Toolkit.getDefaultToolkit().getScreenSize());
    pack();
    setResizable(false);
    show();

    SwingUtilities.invokeLater(new Runnable() {
        public void run() {
            Point p = new Point(0, 0);
            SwingUtilities.convertPointToScreen(p, getContentPane());
            Point l = getLocation();
            l.x -= p.x;
            l.y -= p.y;
            setLocation(p);
        }
    });
}

Dimension dim = Toolkit.getDefaultToolkit().getScreenSize();
setBounds(100, 100, (int) dim.getWidth(), (int) dim.getHeight());
setLocationRelativeTo(null);

In Fedora the above problem is not present. But there are complications involved with Gnome or KDE. So better be careful. Hope this helps.

Easiest fix ever:

for ( Window w : Window.getWindows() ) {
    GraphicsEnvironment.getLocalGraphicsEnvironment().getDefaultScreenDevice().setFullScreenWindow( w );
}

Just use this code :

import java.awt.event.*;
import javax.swing.*;

public class FullscreenJFrame extends JFrame {
    private JPanel contentPane = new JPanel();
    private JButton fullscreenButton = new JButton("Fullscreen Mode");
    private boolean Am_I_In_FullScreen = false;
    private int PrevX, PrevY, PrevWidth, PrevHeight;

    public static void main(String[] args) {
        FullscreenJFrame frame = new FullscreenJFrame();
        frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
        frame.setSize(600, 500);
        frame.setVisible(true);
    }

    public FullscreenJFrame() {
        super("My FullscreenJFrame");

        setContentPane(contentPane);

        // From Here starts the trick
        FullScreenEffect effect = new FullScreenEffect();

        fullscreenButton.addActionListener(effect);

        contentPane.add(fullscreenButton);
        fullscreenButton.setVisible(true);
    }

    private class FullScreenEffect implements ActionListener {
        @Override
        public void actionPerformed(ActionEvent arg0) {
            if (Am_I_In_FullScreen == false) {
                PrevX = getX();
                PrevY = getY();
                PrevWidth = getWidth();
                PrevHeight = getHeight();

                // Destroys the whole JFrame but keeps organized every Component
                // Needed if you want to use Undecorated JFrame dispose() is the
                // reason that this trick doesn't work with videos.
                dispose();
                setUndecorated(true);

                setBounds(0, 0, getToolkit().getScreenSize().width,
                        getToolkit().getScreenSize().height);
                setVisible(true);
                Am_I_In_FullScreen = true;
            } else {
                setVisible(true);
                setBounds(PrevX, PrevY, PrevWidth, PrevHeight);
                dispose();
                setUndecorated(false);
                setVisible(true);
                Am_I_In_FullScreen = false;
            }
        }
    }
}

I hope this helps.