Question

Im working on a simple platformer in java and am having trouble with the jumping of the player. What is happening is that if I hold down the spacebar the player just keeps going up. I need some way to have the player jump once per spacebar press. My current KeyListener setup for jumping is below.

public void keyPressed(KeyEvent e) {
    int key = e.getKeyCode();

    if (key == KeyEvent.VK_SPACE)
        Input.jump = true;
}

public void keyReleased(KeyEvent e) {
    int key = e.getKeyCode();

    if (key == KeyEvent.VK_SPACE)
        Input.jump = false;
}

In my Player class I have the following for toggling the jump

if(Input.jump == true) jump();

Any help would be much appreciated!

Answer 1

The problem isn’t that the event is being called lots per key press – the problem is that Input.jump is true until you let go of the key.

You might try something like this:

public void keyPressed(KeyEvent e) {
    int key = e.getKeyCode();
    if (key == KeyEvent.VK_SPACE)
        if(!Input.jump) {
            velocity += jumpVelocity;
        }
        Input.jump = true;
}

public void keyReleased(KeyEvent e) {
    int key = e.getKeyCode();

    if (key == KeyEvent.VK_SPACE)
        Input.jump = false;
}

Then use velocity to move your character up.

Or you can use a boolean of some kind – it really depends on your situation. If you’re using a boolean, then you’d want to have something like the following code:

public void keyPressed(KeyEvent e) {
    int key = e.getKeyCode();
    if (key == KeyEvent.VK_SPACE)

        if(!Input.jump) {
            isJumping = true;
        } else {
            isJumping = false;
        }
        Input.jump = true;
}