I made now a lot more progress. Anyway there is one point I did like to ask: The model component in Asteroid Panic just hold a string. To avoid typos I added some const vars. But when ever I want to add a new one I have to touch this file. I now thougth of storing an object derived from a base class instead that simple sting. just that the java compiler can help me with typos and I then would not to have to touch The model component for new sfuff. This objects ar just used like a string 
But I’m little unsure with that.