I NEED HELP!

import greenfoot.*;  // (World, Actor, GreenfootImage, Greenfoot and MouseInfo)

/**
 * Write a description of class ball here.
 * 
 * @author (your name) 
 * @version (a version number or a date)
 */
public class ball extends SmoothMover
{
    /**
     * Act - do whatever the ball wants to do. This method is called whenever
     * the 'Act' or 'Run' button gets pressed in the environment.
     */
    private double[] direction;
 
    public ball()
    {
        direction = new double[] {1, -1}; //-45°
    }
 
    public void act()
    {
        setLocation(getExactX()+direction[0], getExactY());
        if (isTouching(Paddle.class))
        {
            direction[0] *= -1;
        }
        setLocation(getExactX(), getExactY()+direction[1]);
        if (isTouching(Paddle.class))
        {
            direction[1] *= -1;
        }
    }
}