Connection between Class and primitive types?

Question

I thought I understand concept of class(object) Class, but reading about it in Java API, I found this:

The primitive Java types (boolean, byte, char, short, int, long, float, and double), and the keyword void are also represented as Class objects.

docs.oracle.com/javase/7/docs/api/java/lang/Void.html The Void class is an uninstantiable placeholder class to hold a reference to the Class object representing the Java keyword void. — Suresh Atta
docs.oracle.com/javase/8/docs/api/java/lang/Integer.html#TYPE — fabian
What exactly you are wondering about? I meant, you don't get the point of object and class concept OR primitive type classes? — NawaMan
@NawaMan I guess it's primitive type classes. When I read quote above, I thought I misunderstood concept of Class. I didn't know connection of primitive types with Class. — misty
@LazyLady I recommend you to revise the question to reflex that. :-D — NawaMan

xenteros xenteros · Accepted Answer · 2016-08-09T11:43:04

The phenomenon on autoboxing and unboxing is what you're looking for. In java there are some primitives for comfort purposes. They all have wrapper classes. These are: Integer, Double, Boolean etc.

Autoboxing is responsible for wrapping primitives into Wrappers each time the Wrapper is expected but a primitive is passed. On the other hand unboxing comes. When it's a primitive expected but Wrapper passed unboxing will manage to extract the proper value.

It's well described here

Example:

Integer one = new Integer(1);
int i = one.intValue();

void printInteger(int i) {
    System.out.println(i);
}

printInteger(one);

No exception will be thrown - one will be unboxed to int and printed.

Connection between Class and primitive types?

2 Answers