Java: Integer vs int
Integer is a class, or a reference type, defined in the standard library. It stores a reference to an object containing a value (a "box").
int on the other hand, is a primitive type and part of the language itself. It stores an actual value.
We say that
Integer is the wrapper type for
int, and objects of type
Integer are boxed values.
Continue reading here:
Java: Primitives vs Objects and References
Java: Wrapper Types