Simulate a key held down in Java

Question

I'm looking to simulate the action of holding a keyboard key down for a short period of time in Java. I would expect the following code to hold down the A key for 5 seconds, but it only presses it once (produces a single 'a', when testing in Notepad). Any idea if I need to use something else, or if I'm just using the awt.Robot class wrong here?

Robot robot = null; 
robot = new Robot();
robot.keyPress(KeyEvent.VK_A);
Thread.sleep(5000);
robot.keyRelease(KeyEvent.VK_A);

Answer 1

There is no keyDown event in java.lang.Robot. I tried this on my computer (testing on a console under linux instead of with notepad) and it worked, producing a string of a's. Perhaps this is just a problem with NotePad?

Answer 2

Thread.sleep() stops the current thread (the thread that is holding down the key) from executing.

If you want it to hold the key down for a given amount of time, maybe you should run it in a parallel Thread.

Here is a suggestion that will get around the Thread.sleep() issue (uses the command pattern so you can create other commands and swap them in and out at will):

public class Main {

public static void main(String[] args) throws InterruptedException {
    final RobotCommand pressAKeyCommand = new PressAKeyCommand();
    Thread t = new Thread(new Runnable() {

        public void run() {
            pressAKeyCommand.execute();
        }
    });
    t.start();
    Thread.sleep(5000);
    pressAKeyCommand.stop();

  }
}

class PressAKeyCommand implements RobotCommand {

private volatile boolean isContinue = true;

public void execute() {
    try {
        Robot robot = new Robot();
        while (isContinue) {
            robot.keyPress(KeyEvent.VK_A);
        }
        robot.keyRelease(KeyEvent.VK_A);
    } catch (AWTException ex) {
        // Do something with Exception
    }
}

  public void stop() {
     isContinue = false;
  }
}

interface RobotCommand {

  void execute();

  void stop();
}

Answer 3

Just keep pressing?

import java.awt.Robot;
import java.awt.event.KeyEvent;

public class PressAndHold { 
    public static void main( String [] args ) throws Exception { 
        Robot robot = new Robot();
        for( int i = 0 ; i < 10; i++ ) {
            robot.keyPress( KeyEvent.VK_A );
        }
    }
}

I think the answer provided by edward will do!!