Generics and Unboxing

When using legacy (non-type safe) collections—watch out for unboxing problems! If you declare a non-generic collection, the get() methodALWAYS returns a reference of type java.lang.Object. Remember that unboxing can't convert a plain old Object to a primitive, even if that Object reference points to an Integer (or some other primitive) on the heap. Unboxing converts only from a wrapper class reference (like an Integer or a Long) to a primitive.