Change to next level

My code for Sonnekind:

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

/**
 * Write a description of class Sonnekind here.
 * 
 * @author (your name) 
 * @version (a version number or a date)
 */
public class Sonnekind extends Actor
{
    private int energy = 30;
    private int Teletubbieseaten = 0;
    private int checkNextLevel;
    private GreenfootImage Image3;
    private GreenfootImage Image4;
    private int Teletubby1;
    
    public Sonnekind()
    {
        Image3 = new GreenfootImage("sbkklein1.png");
        Image4 = new GreenfootImage("sbkklein2.png");
        setImage(Image3);
        
    }
    
    
    public void switchImage()
    {
        if (getImage() == Image3) 
        {
            setImage(Image4);
        }
        else
        {
            setImage(Image3);
        }
    }
   
     
    public void act()
    {
        if (Greenfoot.isKeyDown("left")) 
        {
            setRotation(180);
            bewegen();
        }
        if (Greenfoot.isKeyDown("right")) 
        {
            setRotation(0);
            bewegen();
        }
        if (Greenfoot.isKeyDown("up"))
        {
            setRotation(270);
            bewegen();
        }
        if (Greenfoot.isKeyDown("down"))
        {
            setRotation(90);
            bewegen();
        }
      Actor Teletubby1;
        Teletubby1 = getOneObjectAtOffset(0, 0, Teletubby1.class);
        if (Teletubby1 !=null)
        {
            eatTeletubby1();
        }
      Actor Teletubby2;
      Teletubby2 = getOneObjectAtOffset(0, 0, Teletubby2.class);
        if (Teletubby2 !=null)
        {
            eatTeletubby2();

        }
      
        switchImage();
      NextWorld();
    }

        
    
    
    
    public void eatTeletubby1()
{
    Actor Teletubby1 = this.getOneObjectAtOffset(0, 0, Teletubby1.class);
     if(Teletubby1 != null) 
     {   Teletubbieseaten = Teletubbieseaten + 1;
        Greenfoot.playSound("winke.mp3");
        energy = energy + 10;
        getWorld().removeObject(Teletubby1);    
        ((Teletubbieswelt)getWorld()).Teletubby1Hinzufügen() ;
     }
}

public void eatTeletubby2()
{
     Actor Teletubby2 = this.getOneObjectAtOffset(0, 0, Teletubby2.class);
    if(Teletubby2 != null) 
    {   Teletubbieseaten = Teletubbieseaten + 1;
        Greenfoot.playSound("winke.mp3");
        energy = energy + 10;
        getWorld().removeObject(Teletubby2);    
        ((Teletubbieswelt2)getWorld()).Teletubby2Hinzufügen() ;
    }
}


public void bewegen()
{
        if(energy >=1) 
    {
        
        move(1);
        energy = energy - 1;
    }
    else 
    {
        ((Teletubbieswelt)getWorld()).removeObjekte() ;
    }   
}



    public int getEnergy()
    {
        return energy;
    }
    
    
     private void NextWorld()  
     {
          if (energy >= 40)  
      {  
         Teletubbieswelt2 ttw2 = new Teletubbieswelt2();  
           
         Greenfoot.setWorld(ttw2);  
      }      
     
    }
} 



my code for Teletubby1

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

/**
 * Write a description of class Teletubby1 here.
 * 
 * @author (your name) 
 * @version (a version number or a date)
 */
public class Teletubby1 extends Actor
{
    private GreenfootImage Image1;
    private GreenfootImage Image2;
    private int checkNextLevel;
    private int energy = 30;
    
    public Teletubby1()
    {
        Image1 = new GreenfootImage("po1klein.png");
        Image2 = new GreenfootImage("po2klein.png");
        setImage(Image1);
    }
    /**
     * Act - do whatever the Teletubby1 wants to do. This method is called whenever
     * the 'Act' or 'Run' button gets pressed in the environment.
     */
    public void act() 
    {
       
       switchImage();
       moveAround();
       NextWorld();
    }   
    
    public void switchImage()
    {
        if (getImage() == Image1) 
        {
            setImage(Image2);
        }
        else
        {
            setImage(Image1);
        }
    }
    
    public void moveAround()
    {
        move(1);
        if (getX() <=5 || getX() >= getWorld().getWidth() -5)
        {
            turn(75);
        }
        if (getY() <=5 || getY() >= getWorld().getHeight() -5)
        {
            turn(75);
        }
    }
    
    private void NextWorld()  
     {
          if (energy >= 40)  
      {  
         Teletubbieswelt2 ttw2 = new Teletubbieswelt2();  
           
         Greenfoot.setWorld(ttw2);  
      }      
     
    }
    
    
}

if (getWorld() instanceof Teletubbieswelt) ((Teletubbieswelt) getWorld()).Teletubby1Hinzufügen(); else ((Teletubbieswelt2) getWorld()).teletubby2Hinzufügen();