java - Error setting annotation value as Class<?> from a constant, why?

Question

This is my annotation:

@Target( { ElementType.METHOD } )
@Retention(RetentionPolicy.RUNTIME)
public @interface AuditUpdate
{
    Class<?> value();
}

By this way it is ok:

@AuditUpdate(User.class)
void someMethod(){}

But by this way:

private static final Class<?> ENTITY_CLASS = User.class;
@AuditUpdate(ENTITY_CLASS)
void someMethod(){}

I have this compilation error:

The value for annotation attribute AuditUpdate.value must be a class literal

Why? What does that mean?

Thank you.

Answer 1

It means that you must pass a class literal, rather than a variable (even if constant).

A class literal is well defined in the JLS:

15.8.2 Class Literals

A class literal is an expression consisting of the name of a class, interface, array, or primitive type followed by a `.' and the token class. The type of a class literal is Class. It evaluates to the Class object for the named type (or for void) as defined by the defining class loader of the class of the current instance.

So, you can't do that.