float speed = 4f;
    Vec2 velocity = new Vec2(0, 0);

        public void move(double d, double e){
                this.x += d;
                this.y += e;
        }

        public void checkPlayerMove(GameKeyboard keyboard){

                /*if(keyboard.pressedKeys.contains((Integer) Keyboard.KEY_W)
                && keyboard.pressedKeys.contains((Integer) Keyboard.KEY_A)){
                        this.move(-speed / Math.sqrt(2), speed / Math.sqrt(2));
                }

                else if(keyboard.pressedKeys.contains((Integer) Keyboard.KEY_W)
                && keyboard.pressedKeys.contains((Integer)      Keyboard.KEY_D)){
                        this.move(speed / Math.sqrt(2), speed / Math.sqrt(2));
                }

                else if(keyboard.pressedKeys.contains((Integer) Keyboard.KEY_S)
                && keyboard.pressedKeys.contains((Integer) Keyboard.KEY_A)){
                        this.move(-speed / Math.sqrt(2), -speed / Math.sqrt(2));
                }

                else if(keyboard.pressedKeys.contains((Integer) Keyboard.KEY_S)
                && keyboard.pressedKeys.contains((Integer) Keyboard.KEY_D)){
                        this.move(speed / Math.sqrt(2), -speed / Math.sqrt(2));
                }

                else if(keyboard.pressedKeys.contains((Integer) Keyboard.KEY_W)){
                        this.move(0, speed);
                }

                else if(keyboard.pressedKeys.contains((Integer) Keyboard.KEY_A)){
                        this.move(-speed, 0);
                }

                else if(keyboard.pressedKeys.contains((Integer) Keyboard.KEY_S)){
                        this.move(0, -speed);
                }

                else if(keyboard.pressedKeys.contains((Integer) Keyboard.KEY_D)){
                        this.move(speed, 0);
                }*/
        //These two commented and uncommented code blocks yield the same result
        velocity = new Vec2(0, 0);
        if (/*pressed left*/) {
             velocity = new Vec2(velocity.x - speed, velocity.y);
        }
        if (/*pressed right*/) {
            velocity = new Vec2(velocity.x + speed, velocity.y);
        }
        if (/*pressed up*/) {
             velocity = new Vec2(velocity.x, velocity.y - speed);
        }
        if (/*pressed down*/) {
             velocity = new Vec2(velocity.x, velocity.y + speed);
        }
        velocity = velocity.normalize();
        //Slick2D's library didn't have the .mul() method, so I instead increased the velocity by speed
        x += velocity.x;
        y += velocity.y;

        }