I think it's a fairly simple question, but I can't figure out how to do this properly.
I've got an empty arraylist:
ArrayList<object> list = new ArrayList<object>();
You can do it like this:
list.add(1, object1) list.add(2, object3) list.add(2, object2)
After you add object2 to position 2, it will move object3 to position 3.
If you want object3 to be at position3 all the time I'd suggest you use a HashMap with position as key and object as a value.