game

Greenfoot.setWorld(new EndWorld());

if (getObjects(Objects.class).isEmpty() || counter.value == 2) // the counter.value won't necessarily work for you, it's just an example
{
    Greenfoot.setWorld(new EndWorld());
}

if (getObjects (FormulaBottle.class).isEmpty() )
    {
        Greenfoot.setWorld (new EndOfLevel() );
    }

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

/**
 * This class Level2 here displays the second level for the user to play.
 * 
 * Jacqueline Reilly
 * January 18, 2017
 */
public class Level2 extends World
{
    //Instance for counters
    Counter counter = new Counter ();
    PlanktonCounter PCounter = new PlanktonCounter ();
    /**
     * Constructor for objects of class Level2.
     * 
     */
    public Level2()
    {    
        // Create a new world with 600x400 cells with a cell size of 1x1 pixels.
        super (950, 700, 1); 
        
        //Adding counter
        addObject(counter, 91, 137);
        addObject (PCounter, 97, 186);
        
        //Making background fit the screen
        GreenfootImage Bg = new GreenfootImage ("background.jpg");
        Bg.scale (getWidth (), getHeight ());
        setBackground (Bg);
        
        //Adding the platforms 
        Platform platform = new Platform ();
        addObject (platform,234, 618);
        Platform platform1 = new Platform ();
        addObject (platform1, 655, 518);
        
        //Adding characters
        addObject (new MrKrabs(), 210, 500);
        addObject (new Plankton(), 78, 476);
        
        //Adding object for Mr. Krabs to collect
        KrabbyPatty krabbyPatty = new KrabbyPatty ();
        addObject (krabbyPatty, 393, 481);
        KrabbyPatty krabbyPatty1 = new KrabbyPatty ();
        addObject (krabbyPatty1, 601, 357);
        
        //Adding object for Plankton to collect
        FormulaBottle bottle = new FormulaBottle ();
        addObject (bottle, 293, 330);
        FormulaBottle bottle1 = new FormulaBottle ();
        addObject (bottle1, 825, 351);
        
        //

    
    
    if (getObjects(FormulaBottle.class).isEmpty() )
    {
        Greenfoot.setWorld (new EndOfLevel() );
    }
}
    
    public Counter getCounter(){
        return counter; 
    }
    
    public PlanktonCounter getPlankton() {
     return PCounter;
    }
}

public void act()
{
    // code here
}