private void checkMovement() {
        // Gets the exact location.
        double x = getExactX();
        double y = getExactY();

        // Stores the original location so that the player can stay in that location whenever they try to go through an object that they aren't supposed to.
        double originalX = x;
        double originalY = y;

        GreenfootSound walking = new GreenfootSound("walking.mp3");

        // Move up whenever the "w" key is pressed.
        if (Greenfoot.isKeyDown("w")) {
            y -= speed;
        }

        // Move down whenever the "s" key is pressed.
        if (Greenfoot.isKeyDown("s")) {
            y += speed;
        }

        // Move left whenever the "a" key is pressed, while also flipping the player to face the left.
        if (Greenfoot.isKeyDown("a")) {
            x -= speed;
            if (facingRight) {
                flipImage();
                facingRight = false;
            }
        }

        // Move right whenever the "d" key is pressed, while also flipping the player to face the right.
        if (Greenfoot.isKeyDown("d")) {
            x += speed;
            if (!facingRight) {
                flipImage();
                facingRight = true;
            }
        }

        // Temporarily move to the new location to test for collisions.
        setLocation(x, y);

        // Return to the original position if colliding with a Tree.
        if (isTouching(Tree.class)) {
            setLocation(originalX, originalY);
        }

        // Return to the original position if colliding with a Barrier.
        if (isTouching(Barrier.class)) {
            setLocation(originalX, originalY);
        }
    }