How to Implement Fullscreen Mode in Java Across Multiple Monitors

How can I enable fullscreen mode in a Java application that spans multiple monitors?

GraphicsDevice[] devices = GraphicsEnvironment.getLocalGraphicsEnvironment().getScreenDevices();

for (GraphicsDevice device : devices) {
    JFrame frame = new JFrame(device.getDefaultConfiguration());
    frame.setUndecorated(true);
    frame.setExtendedState(JFrame.MAXIMIZED_BOTH);
    frame.setVisible(true);
}

Enabling fullscreen mode for a Java application that can work across multiple monitors involves utilizing the Java AWT (Abstract Window Toolkit) library. This process requires understanding the graphical device configuration and making use of the JFrame class to create and manage windows for each monitor.

GraphicsDevice[] devices = GraphicsEnvironment.getLocalGraphicsEnvironment().getScreenDevices();

for (GraphicsDevice device : devices) {
    JFrame frame = new JFrame(device.getDefaultConfiguration());
    frame.setUndecorated(true);
    frame.setExtendedState(JFrame.MAXIMIZED_BOTH);
    frame.setVisible(true);
}

Causes

• Java does not automatically detect multiple monitors for fullscreen applications.
• Different operating systems and screen configurations may require specific implementation details.

Solutions

• Use the `GraphicsEnvironment` class to retrieve all available `GraphicsDevice` instances.
• Create a separate `JFrame` for each monitor and set them to fullscreen mode individually.
• Set each `JFrame` to be undecorated to remove window borders and maximize space.

Mistake: Forgetting to set undirected JFrame, leading to window borders appearing.

Solution: Always call `frame.setUndecorated(true)` before making the frame visible.

Mistake: Not accounting for different screen resolutions or DPI settings.

Solution: Calculate and adjust sizes and positions carefully based on the `device.getDefaultConfiguration().getBounds()`.