I'm not sure how to make the ball bounce up and down.<br>
Here's my code:

    while (lives > 0 && bricks > 0)
    {
        double velocity = 2.0; 
        
        move(ball, 0, velocity);
        
        if (getY(ball) <= 0)
        {
            velocity = -velocity;
        }
        else if (getY(ball) + 2 * RADIUS >= getHeight(window))
        {
            velocity = -velocity;
        }
         
        pause(10);
    }