Java jnativehook typing a string not working

Question

I'd like to type: "/ammo" when I type ALT+A. The program runs but it seems like to stop right after the running: I press alt+A or A and the code is not doing anything at all.

package jnativehook01;

import java.awt.AWTException;
import java.awt.Robot;
import java.awt.Toolkit;
import java.awt.datatransfer.Clipboard;
import java.awt.datatransfer.StringSelection;
import java.awt.event.KeyEvent;

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

public class Example implements NativeKeyListener {
    public void nativeKeyPressed(NativeKeyEvent e) {

        if (NativeKeyEvent.getKeyText(e.getKeyCode()).equals("A")) {
            try {
                GlobalScreen.unregisterNativeHook();

                Robot bot;
                try {
                    bot = new Robot();

                    String text = "/ammo";
                     StringSelection stringSelection = new StringSelection(text);
                     Clipboard clipboard = Toolkit.getDefaultToolkit().getSystemClipboard();
                     clipboard.setContents(stringSelection, stringSelection);

                    //type: /ammo
                    bot.keyPress(KeyEvent.VK_T);
                    bot.keyRelease(KeyEvent.VK_T);


                } catch (AWTException e1) {

                }




            } catch (NativeHookException e1) {
            }
        }
    }

    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) {

        new Example();
    }
}

Answer 1

Ok, now it's working:

package jnativehook01;

import org.jnativehook.GlobalScreen;
import org.jnativehook.NativeHookException;
import org.jnativehook.keyboard.NativeKeyEvent;
import org.jnativehook.keyboard.NativeKeyListener;
import java.util.logging.*;
import java.awt.AWTException;
import java.awt.Robot;
import java.awt.Toolkit;
import java.awt.datatransfer.Clipboard;
import java.awt.datatransfer.StringSelection;
import java.awt.event.KeyEvent;
import java.awt.event.InputEvent;

public class Example implements NativeKeyListener {
    public void nativeKeyPressed(NativeKeyEvent e) {
        if (NativeKeyEvent.getKeyText(e.getKeyCode()).equals("A")) {
            Robot bot;
            try {
                String text = "/ammo";
                StringSelection stringSelection = new StringSelection(text);
                Clipboard clipboard = Toolkit.getDefaultToolkit().getSystemClipboard();
                clipboard.setContents(stringSelection, stringSelection);

                bot = new Robot();

                for (int i = 0; i < 10; i++) {
                    //t
                    bot.keyPress(KeyEvent.VK_T);
                    bot.delay(100);
                    bot.keyRelease(KeyEvent.VK_T);

                    bot.delay(500);

                    bot.keyPress(KeyEvent.VK_CONTROL);
                    bot.keyPress(KeyEvent.VK_V);
                    bot.keyRelease(KeyEvent.VK_V);
                    bot.keyRelease(KeyEvent.VK_CONTROL);

                    bot.delay(500);

                    //Enter

                    bot.keyPress(KeyEvent.VK_ENTER);
                    bot.keyRelease(KeyEvent.VK_ENTER);

                    bot.delay(1000);

                    bot.keyPress(KeyEvent.VK_ENTER);
                    bot.keyRelease(KeyEvent.VK_ENTER);

                    bot.delay(400);
                }

            } catch (AWTException e1) {
            }

        }
    }

    public void nativeKeyReleased(NativeKeyEvent e) {

    }

    public void nativeKeyTyped(NativeKeyEvent e) {

    }

    public static void main(String[] args) {
        Example ex = new Example();
        try {
            GlobalScreen.registerNativeHook();
            Logger logger = Logger.getLogger(GlobalScreen.class.getPackage().getName());
            logger.setLevel(Level.OFF);
        } catch (NativeHookException eb) {
            System.out.println(eb.getMessage());

        }
        GlobalScreen.addNativeKeyListener(ex);
    }

}

Answer 2

There are still a few problems with your code.

if (NativeKeyEvent.getKeyText(e.getKeyCode()).equals("A")) { This is not the correct way to check for the A key. This will check to see if AWT produces the ascii 'A' for that key. These values could be overridden by the JVM at runtime. You should check for the NativeKeyEvent.VK_A constant. You also fail to check for the ALT flag on that key event. Something like the following is more of what you are looking for.

if (e.getKeyCode() == NativeKeyEvent.VC_A && e.getModifiers() & NativeInputEvent.ALT_MASK) {

A note on thread safety. You are relying on AWT inside of the key callback, however, this library does not use AWT to dispatch events by default. You need to take a look at the Thread Safety section of the wiki for Thread Safe examples.

You may choose to replace the Robots class with GlobalScreen.postNativeEvent(...) for convenience, to omit Swing/AWT, but it is not required.

A note on blocking inside of the event listener callback. If you block inside this function, via sleep or other long running process, you may cause a delay in key event delivery by the OS or worse, library removal by some operating systems. This removal is outside the control of the library and controlled by the OS.