“Warning: [unchecked] unchecked cast” when casting Object to ArrayList

Question

Strange situation - below is the code:

ArrayList listArr = new ArrayList<>();
Object[] obj = new Object[]{\"str\", listArr};

String st         


        

Answer 1

This is because the compiler can not verify the internal types at the list level, so you need to first verify for list. And the internal types individually.

Instead of ArrayList list = (ArrayList) obj[1];

It should be ArrayList list = (ArrayList) obj[1];