I don't realy know what you mean by vector. The stuff that looks like this: GreenfootImage is called Array. An Array is a variable that saves many objects from one type in only one variable. In your case the problem is that you try to set the object at the first and second field of the array which doesn't even exist. To fix it you have to change this line: GreenfootImage img; into this: GreenfootImage img = new GreenfootImage;//or a higher value if you want to use more images.

Thank you very much. I wrote vector because that's how people use to say in my language. Didn't know that Array is the correct term. :)