Java: Short (class) vs short (primitive)

A Short is a class, or a reference type, defined in the standard library. It stores a reference to an object containing a value (a "box").

A short on the other hand, is a primitive type and part of the language itself. It stores an actual value.

We say that Short is the wrapper type for short, and objects of type Short are boxed values.

Continue reading here:

Java: Primitives vs Objects and References
Java: Wrapper Types