Java - KeyListener issues

Question

I am a little new to Java so, sorry if I'm doing something wrong. I want my program to say The W key has been pressed when I press the W button. I've been having a little bit of problems with this. Here is an outline of my code:

public class Main extends JFrame implements ActionListener, KeyListener {

    public void keyListener(){
        addKeyListener(this);
        setFocusable(true);
        setFocusTraversalKeysEnabled(false);
    }



    public void keyPressed(KeyEvent e) {
        int code = e.getKeyCode();
        if (code == KeyEvent.VK_W){
        System.out.println("W is pressed");
        }
    }




    @SuppressWarnings("null")
    public static void main(String[] args) throws InterruptedException {
    //Initial things like variables and JFrame setup (Like: JFrame frame = new JFrame("FrameDemo");)
        for(step = 0; step == step; step++ ){
            for(i = 0; i < constructor.length; i++){
            //Some code
            constructor[i].draw(g);
            }
        }
    }
}

The KeyListener doesn't respond whatsoever. I think this might be because of the loop but I honestly have no idea. Can anyone expain why this is happening and how I could fix it?

Answer 1

The thing is: just declaring a class to be a KeyListener ... doesn't magically create that connection that is required at runtime.

In other words: the idea of a Listener is that it is registered at some point; and only registered Listeners will be notified about events.

Therefore you only need to call

addKeyListener(this)

somewhere within your class; for example within your constructor.

Or more specifically: you created a method keyListener() that would make that addKeyListener() call ... but: there is probably no call to keyListener() in your source code!

And just for the record: keyListener() isn't a good name for a method; you should better call it registerListeners() for example.