Object not found

The problem is not in the code given in the image. It stems from your act method, maybe to a previously called method (previous to the call to the first method in the image).

but if it is between but if i type : between x=212 and x = 116 it works perfect.

import greenfoot.*; // (World, Actor, GreenfootImage, Greenfoot and MouseInfo) /** * Write a description of class Player here. * * @author (your name) * @version (a version number or a date) */ public class Player extends Actor { /** * Act - do whatever the Player wants to do. This method is called whenever * the 'Act' or 'Run' button gets pressed in the environment. */ public void act() { checkKey(); collisionStraßenrand(); } private void checkKey() { if (Greenfoot.isKeyDown("a")) { setLocation(getX()-4, getY()); } if (Greenfoot.isKeyDown("d")) { setLocation(getX()+4, getY()); } if (Greenfoot.isKeyDown("w")) { setLocation(getX(), getY()-5); } if (Greenfoot.isKeyDown("s")) { setLocation(getX(), getY()+4); } } private void collisionStraßenrand() { if (getX() >= 582 && getX() <= 585) { explodiere(); } if (getX() >= 212 && getX() <= 217) { explodiere(); } } public void explodiere() { Explosion explosion1 = new Explosion(); getWorld().addObject( explosion1 , getX() , getY()); getWorld().removeObjects(getWorld().getObjects(Player.class)); } } this is my source code and it only crashes if my actor is between 582 and 585

Oh, sorry -- it is in that code given, then. Add the following second line after the first instance of the first line: