“Iterable cannot be cast to List” - Isn't `List` a type of `Iterable`?

Question

I called a getElements method which returns Iterable.

I did this:

List elements = (List

        

Answer 1

Not all Iterables are Lists, thus it's not safe to cast an arbitrary Iterable to a List.

Take any Set for instance, a HashSet is Iterable but the elements has no order, so it can't implement the List interface, and is thus not a List.