hi wonkty!
As you said,ArrayList is the subtype of List, so it is equal to say
List<Integer> l = new ArrayList<Integer>();
but is the below correct?
List<Integer> l; ArrayList<Integer> a=l;
Pay more attention to the method return type:List<E>
so if the output is :ArrayList<Integer>output = null;
it will get
utput=List<Integer>.
dose it correct?