Java generics incompatible types (no instance(s) of type variable(s) T exist)

ArrayList is an implementation of List interface.
So all ArrayList instances are List instances but all List instances are not necessarily ArrayList.

So when you call this method :

public static <T> List<T> inRange(List<T> list, int index, int range) {

you cannot assign its result to an ArrayList as you are doing :

ArrayList<View> inRange = Helper.inRange(...);

Go on to program by interface and use List in both sides :

List<View> inRange = Helper.inRange(...);