Except when you add final, then there is little reason to have the less specific type. But i see where you come from, it feels a bit sloppy to not document the

Except when you add final, then there is little reason to have the less specific type. But i see where you come from, it feels a bit sloppy to not document the intention that the variable _could_ be any kind of list, even though it happens to be an ArrayList. Not "this may lead to nasty bugs"-sloppy, but a slight case of "this won't win any beauty contests"-sloppy.