world

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

/**
 * Write a description of class MyWorld here.
 * 
 * @author (Nosson1459) 
 * @version (12/6/2016)
 */
public class MyWorld extends World
{
    public int variable=4;
    /**
     * Constructor for objects of class MyWorld.
     * 
     */
    public MyWorld()
    {    
        // Create a new world with 600x400 cells with a cell size of 1x1 pixels.
        super(600, 400, 1); 
    }
    public void act()
    {
        variable++;
    }
}

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

/**
 * Write a description of class MyWorld2 here.
 * 
 * @author (Nosson1459) 
 * @version (12/6/2016)
 */
public class MyWorld2 extends World
{

    /**
     * Constructor for objects of class MyWorld2.
     * 
     */
    public MyWorld2()
    {    
        // Create a new world with 600x400 cells with a cell size of 1x1 pixels.
        super(600, 400, 1); 
    }
    public void act()
    {
        // on this line and any more needed below it, should be the coding for retrieving and using a variable from a different world
    }
}

// replace line 11 with
public static int variable;
// and insert the following at line 20
variable = 4;

int var = MyWorld.variable;

MyWorld.variable = 0;