How to increase jump height when holding space

private void mainLoop() {
        if (jumping) {
            jumpTime++;
            if (inAir)
              return;
                inAir = true;
                canJump = false;

                // need to set airspeed depending on jump time here
                airSpeed -= jumpHeight;
            }
        }
    }

    // ====== Jumping ======
    private boolean jumping = false;
    private static final float MAX_JUMP_HEIGHT = 8.0f * SCALE;
    private static final float MIN_JUMP_HEIGHT = 4.0f * SCALE;
    private float jumpHeight = MIN_JUMP_HEIGHT;
    private float jumpTime = 0.0f;

public void keyPressed(KeyEvent e) {
        if (e.getKeyCode() == KeyEvent.VK_SPACE) {
            player.setJumping(true);
            player.setJumpTime(0);
        }
    }

    public void keyReleased(KeyEvent e) {
        if (e.getKeyCode() == KeyEvent.VK_SPACE) {
            player.setJumping(false);
            player.setCanJump(true);
        }
    }