Java System-Wide Keyboard Shortcut

Question

Is there any way or a library to get a system-wide (global) keyboard shortcut to perform an action in a Java application?

Answer 1

I just found https://github.com/kwhat/jnativehook

Seems to be cross platform.

Here's their sample code for listening for key presses:

import org.jnativehook.GlobalScreen;
import org.jnativehook.NativeHookException;
import org.jnativehook.keyboard.NativeKeyEvent;
import org.jnativehook.keyboard.NativeKeyListener;

public class GlobalKeyListenerExample implements NativeKeyListener {
    public void nativeKeyPressed(NativeKeyEvent e) {
        System.out.println("Key Pressed: " + NativeKeyEvent.getKeyText(e.getKeyCode()));

        if (e.getKeyCode() == NativeKeyEvent.VC_ESCAPE) {
            GlobalScreen.unregisterNativeHook();
        }
    }

    public void nativeKeyReleased(NativeKeyEvent e) {
        System.out.println("Key Released: " + NativeKeyEvent.getKeyText(e.getKeyCode()));
    }

    public void nativeKeyTyped(NativeKeyEvent e) {
        System.out.println("Key Typed: " + e.getKeyText(e.getKeyCode()));
    }

    public static void main(String[] args) {
        try {
            GlobalScreen.registerNativeHook();
        }
        catch (NativeHookException ex) {
            System.err.println("There was a problem registering the native hook.");
            System.err.println(ex.getMessage());

            System.exit(1);
        }

        GlobalScreen.addNativeKeyListener(new GlobalKeyListenerExample());
    }
}

Checking for modifiers is based on bit masks (stuff we all should know but always forget :-P):

    boolean isAltPressed = (e.getModifiers() & NativeKeyEvent.ALT_MASK) != 0;
    boolean isShiftPressed = (e.getModifiers() & NativeKeyEvent.SHIFT_MASK) != 0;

This you could combine with KeyCode:

if (e.getKeyCode() == NativeKeyEvent.VK_2 && isShiftPressed && isAltPressed){...}

This is modified example from here

You should also modify the default logging behavior otherwise it will spam the console:

// Get the logger for "org.jnativehook" and set the level to warning.
Logger logger = Logger.getLogger(GlobalScreen.class.getPackage().getName());
logger.setLevel(Level.WARNING);

// Don't forget to disable the parent handlers.
logger.setUseParentHandlers(false);

Code example is from here