Integer.class vs int.class

Question

What is the difference between Integer.class, Integer.TYPE and int.class?

acc to me

1. Integer.class i

Answer 1

Java handles primitive types versus class types in a schizophrenic way by defining two types for each primitive.

For instance int is the primitive type and Integer the class type. When you use generics, you are forced to use a non-primitive type so ArrayList is allowed but ArrayList not.

Since you sometimes want to perform reflection, this duality results in two classes (how else can you inspect a method public int foo ();).

Say you have a class:

public class Foo {

    private Integer value;

    public int value1 () {
        return value;
    }

    public Integer value2 () {
        return value;
    }

}

The two methods will not always return the same value, since value2() can return null and value1() will throw a runtime error.