What's the difference between between Integer and int and when is either of them use?

Answer 1

int is a primite data type.

Integer is a class, object.

But have something call wrapp and unwap, calling one for other is possible because it (transform one on another, so same thing).

ATTENTION: calling new Integer(number) is DIFERENT to number. It's because "new" create a new object.

Answer 2

int is keyword to define integer in java.
But integer itself is a data type.

Answer 3

Collection api and generic<Type> declarations requires Integer instead of int

new Integer(n); is deprecated