Scrolling Mario Platformer (Part 2)

Open the Mover class, and replace everything inside the "public class Mover extends Actor" with:

protected int speed;

Next, we will add some move methods.

protected int speed;

    /**
     * Move an object to the right
     */
    protected void moveRight()
    {
        setLocation (getX() + speed, getY());
    }
    /**
     * Move an object to the left
     */
    protected void moveLeft()
    {
        setLocation (getX() - speed, getY());
    }

Next we want to adjust the Mario class so that he idles facing left or right:

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

/**
 * Write a description of class Mario here.
 * 
 * @author (your name) 
 * @version (a version number or a date)
 */
public class Mario extends Mover
{
    private final GreenfootImage idleRight = new GreenfootImage("mario-idle.gif");
    private final GreenfootImage idleLeft = new GreenfootImage(idleRight);
   
    public Mario()
    {
        this.speed = 7;
        
        setImage(idleRight);
        idleRight.scale(38,50);
        
        idleLeft.scale(38,50);
        idleLeft.mirrorHorizontally();
        
    }
    
    /**
     * Act - do whatever the Mario wants to do. This method is called whenever
     * the 'Act' or 'Run' button gets pressed in the environment.
     */
    public void act() 
    {
        checkKeys();
    }    
    
    /**
     * This method checks which key has been pressed and then responds with an action.
     */
    private void checkKeys()
    {
        if (Greenfoot.isKeyDown("right"))
        {
            walkRight();
        }
        else if (Greenfoot.isKeyDown("left"))
        {
            walkLeft();
        }
    }
    
    /**
     * Moves Mario right and applies the right-facing images.
     */
    private void walkRight()
    {
        moveRight();
        setImage(idleRight);       
    }
        /**
     * Moves Mario left and applies the left-facing images.
     */
    private void walkLeft()
    {
        moveLeft();
        setImage(idleLeft);
    }
}