You have set 'aktWand' to a specific Wand object (if any are intersecting the center of the cat) and your 'removeObject' statement is removing that object (if any) from the world one time. All other iterations of the loop are just attempts to remove that same Wand object (if any) from the world. If you want to randomly choose one of the Wand objects that are in the world, you will need to randomly choose one from a list of all Wand objects in the world. This means using 'getWorld().getObjects(Wand.class)' instead of 'getOneObjectAtOffset(0, 0, Wand.class)', The 'size' of the returned List object will be needed to determine the random range to choose from and 'get(int)' will be needed to refer to the one randomly chosen. Refer to the List interface API for more info on these methods.

First thanks for your help. Does this mean I have to write these 'size' and 'get(int)' into my command? If yes, how do I have to write them in the command because we just started to use Greenfoot for the first year in school and we never spoke about something like 'size'?

I would presume by your response that you are unfamiliar with Java, as well. All methods are preceded by an object, like in the following: When you do not see an object mentioned, it is because 'this.', which is the default object that methods are executed for, was removed. For example, when you write in your subclass of World, this: you are actually saying: where 'this' refers to the world object that the actor is being added into. 'addObject' is a non-static method that can be found in the World class API. This means it must be executed on a World object. 'removeObject' is another World class method. From an actor class, because 'this' will refer to the actor, we need to run the method on a World object explicitly -- 'getWorld().removeObject(actor);' (which is the same as 'this.getWorld().removeObject(actor);'). Notice what is happening here: a) 'this' refers to an Actor object b) 'getWorld' (an Actor class method) returns a World object c) 'removeObject' (a World class method) removes the given actor from the world The same general path can be realized for getting the size of or an element from a List object: a) 'this' refers to an Actor object b) 'getWorld' (an Actor class method) returns a World object (the world the actor is in) c) 'getObjects' (a World class method) returns a List object (objects in the world on the given class) d) 'size' (a List class method) returns the size of the List object and 'get' (a List class method) returns an element from the List object You will also need 'getRandomNumber(int)' from the Greenfoot class API for choosing a random element from the List object. It is a 'static' method and is not run on an object of the class, but on the class itself:

I cannot say what the '40' is. I can only say that using it as the argument in the 'getRandomNumber' method call will return a number between 0 and 39, inclusive. Other than that, I do not know where you got that number from or why it might be important. will give you the number of Wand objects in the world. You will probably want to use 'wandCount' instead of '40' -- and you should not be using a 'for' loop at all.

You do not need to iterate through the list; just get one random element from it. Line 1 determines how many Wand object are currently in the world. Line 2 randomly picks a number between '0' and 'wandCount-1', inclusive. Line 3 gets the randomly chosen Wand object from the list of Wand objects currently in the world.

:'( I now totally feel so stupid. I try everything but at least I don't understand. I feel so hopeless because you are trying so hard to explain me but my brain doesn't want to understand and I already have to present my game in school tomorrow...I felt so good I came so far with my game and now this.....Now I'm crying the whole time and I'm feeling totally confused...I'm very thankful for the time you spend on explaining me all these things but I don't even know anymore where to write these things and how to use it and at least how to build up these command... :'(

All I wanted was to write im the cat's class that when the cat eats a bird, the bird disappears (I already have this) and that a randomly chosen wall removes so that there's a free place afterwards.

So now I have: if (BördAufFeld () == true) { BördAufnehmen (); int wandCount = getWorld().getObjects(Wand.class).size(); int randomWand = Greenfoot.getRandomNumber(wandCount); Object wand = getWorld().getObjects(Wand.class).get(randomWand); this.getWorld().removeObject(aktWand); } No syntax errors but no wand disappears...

Remove the following line: and change