JVM中的类类[Venner's Book]

Question

I read in Venners book that When a new Type is loaded by the virtual machine , the virtual machine instantiates a new instance of " Class " and associates this instance with the new loaded type in some way ...

now my question : Does The VM instantiates an object of Type " Class " for the " Class " Type itself as being a class which is a type of the three reference types ?

Another Question : When a Class B extends another class A (A is parent) Does the class B info in the method Area include All inherited features of the parent or just specific for it (B) and the Super Class pointer in it's class information is sufficient ? or it's Implementation specific ?

Thanks

Answer 1

Yes, there is an instance of type java.lang.Class which represents the type java.lang.Class itself.

You get access to such a Class instance in two ways, by calling getClass() on an instance of the class or via class literal.

Class<?> str = "foo".getClass(); // represents type String
Class<?> cls = str.getClass(); // represents type Class

or

Class<?> str = String.class; // represents type String
Class<?> cls = Class.class; // represents type Class

Obviously, you can't get the Class instances representing the primitive types or void by calling getClass() on an object, but there are still two ways

Class<?> intType = Integer.TYPE; // represents type int
Class<?> voidType = Void.TYPE; // represents type void

or

Class<?> intType = int.class; // represents type int
Class<?> voidType = void.class; // represents type void

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The existence of a memory region named “method area” is already an implementation detail, so the way the data is organized within it, is even more implementation specific.