I do not think so. Since checkType is called from the act method, which I presume is called by the system while running the animation, the actor must be in the world and therefore no NullPointerException would occur on line 70 (as you have it posted) in the Actions class. The only way that error would occur on that line is if the actor was not in the world at the time that line is executed. I did not see any code removing the object from the world in the act method, the checkType method or the colisionCheck method to that point.

You're right it isn't the colisionCheck(). I put it in commentary and I know get the error at line 92 of the class Enemy. The problem is in the animate() metod.

By commenting the line with the error, you only post-poned the error until the animate code. You need to look backward (not forward) for the cause of the error.

And what means the second fact? As soon as I add an enemy there is an error. If it's not the animate method where could the problem be? The Scenario

For starters, change line 31 of the Enemy class to