Where is .class defined in Java? (Is it a variable or what?)

Question

There are 2 ways to get a class's Class object.

Statically:
```
Class cls = Object.class;
```

From an instance:

Object ob = new Object();  
Class cls = ob.getClass();

Now my question is getClass() is a method present in the Object class, but what is .class? Is it a variable? If so then where is it defined in Java?

score 12 · Accepted Answer · edited Jun 20 '20 at 09:12

That's implemented internally and called a class literal which is handled by the JVM.

The Java Language Specification specifically mentions the term "token" for it.

So .class is more than a variable, to be frank it is not a variable at all. At a broader level you can consider it as a keyword or token.

https://docs.oracle.com/javase/specs/jls/se9/html/jls-15.html#jls-15.8.2

A class literal is an expression consisting of the name of a class, interface, array, or primitive type, or the pseudo-type void, followed by a '.' and the token class.

A class literal evaluates to the Class object for the named type (or for void) as defined by the defining class loader (§12.2) of the class of the current instance.

Just a side note, `Object.getClass()` is defined with the `native` keyword, so it's also handled by JVM. Both ways probably share the same native implementation. — Jai, Jan 22 '18 at 06:54

score 0 · Answer 2 · answered Jan 22 '18 at 13:16

That information resides in the class 'file', although classes need not have a physical .class file in the file system. The JVM takes care of making it available from the class definition, as the other answer states.

See also: https://docs.oracle.com/javase/specs/jvms/se9/html/jvms-4.html

Where is .class defined in Java? (Is it a variable or what?)

2 Answers2