Greenfoot code help

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

/**
 * Write a description of class shot here.
 * 
 * @author (your name) 
 * @version (a version number or a date)
 */
public class shot extends Actor
{
    /**
     * Act - do whatever the shot wants to do. This method is called whenever
     * the 'Act' or 'Run' button gets pressed in the environment.
     */
    int shotImage=1;
    int speedShot=6;
    int position;
    public shot(int direction){
        position=direction;
    }
    public void act() 
    {
        // Add your action code here.
        setImage("bala/bala "+shotImage+".png");
        switch(position){
            case 0:
                setLocation(getX(),getY()-speedShot);
            break;
            case 1:
                setLocation(getX(),getY()+speedShot);
            break;
            case 2:
                setLocation(getX()+speedShot,getY());
            break;
            case 3:
                setLocation(getX()-speedShot,getY());
            break;
        }
        
        Actor roca=getOneObjectAtOffset(0,0,roca.class);
        nave2 boss=(nave2)getOneIntersectingObject(nave2.class);
        if(roca!=null){
            espacio esp=(espacio)getWorld();
            esp.puntos.incrementar();
            esp.crearRocas(1);
            esp.crearEnergia(1);
            getWorld().removeObject(roca);
            if(esp.puntos.obtenerValor()%10==0){
                esp.ponerJefe();
                esp.removeObject(this);
            }
        }
        else if(boss!=null)
        {
            espacio esp=(espacio)getWorld();

            esp.crearEnergia(1);
            esp.lifeboss.decrementar();
            if(esp.lifeboss.obtenerValor()==0)
            {
                esp.removeObject(boss);
                esp.crearRocas(5);
                esp.vidas.incrementar();
                esp.removeObject(esp.lifeboss);
            }
            esp.removeObject(this);
        }
        else
        {
            if((getX()>=getWorld().getWidth()-5)||(getX()<=5)){
            getWorld().removeObject(this);
           }
           else{
               if((getY()>=getWorld().getHeight()-5)||(getY()<=5)){
                   getWorld().removeObject(this);
                }
                else
                    if(shotImage<16)
                        shotImage++;
                        else
                        shotImage=1;
               }
        }
       
    }
}