Bouncing Balls 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 Actor
{
    
    private Vector Vel;
    
   
    public Ball(int xVel, int yVel)
    {
        Vel = new Vector(xVel, yVel); 
        
    }

    public void act() 
    {
        handleWallCollision();
        move();
    }    

    public void move()
    {
        int x = getX() + Vel.getX();
        int y = getY() + Vel.getY();
        setLocation(x, y);
    }

    public boolean hitTopWall()
    {
        if(getY()+getImage().getHeight()/2 > 0)
        {
            return true;
        }
        else
        {
            return false;
        }
    }

    public boolean hitBottomWall()
    {
        if(getY()+getImage().getHeight()/2 < getWorld().getHeight()-1)
        {
            return true;
        }
        else
        {
            return false;
        }
    }

    public boolean hitLeftWall()
    {
        if(getX()+getImage().getWidth()/2 < 0)
        {
            return true;
        }
        else
        {
            return false;
        }
    }

    public boolean hitRightWall()
    {
        if(getX()+getImage().getWidth()/2 > getWorld().getWidth()-1)
        {
            return true;
        }
        else
        {
            return false;
        }
    }

    public  void handleWallCollision()
    {
        if(hitRightWall())
        {
            Vel.horizontalFlip();
        }
        else if(hitLeftWall())
        {   
            Vel.horizontalFlip();
        }
        else if(hitBottomWall())
        {
            Vel.verticalFlip();
        }
        else if(hitTopWall())
        {
            Vel.verticalFlip();
        }

    }
}