Why are protected members allowed in final java classes?

Question

Why are protected members allowed in final classes?

Shouldn't this be a compile-time error?

Edit: as people have pointed out, you can get same package access by using the default modifier instead. It should behave in exactly the same manner, because protected is just default + sub-classes, and the final modifier explicitly denies subclassing, so I think the answer is more than just to provide same package access.

Answer 1

Because protected members can be accessed by other classes in the same package, as well as subclasses.

Answer 2

The protected modifier also allows access within the same package, not just to subclasses. So it's not completely meaningless on a final class.

Answer 3

You can argue that, but there's no real harm anyway. A non-final class may also have a protected member, but no subclass, it won't bother anybody either.

Answer 4

The argument stated here that protected members can be accessed by classes of the same package is valid, but in this case protected becomes equal to the default visibility (package-private), and the question remains - why are both allowed.

I'd guess two things:

• no need to forbid it
• a class may be made final temporarily, until a design decision is made. One should not go and change all visibility modifiers each time he adds or removes final

Answer 5

The protected modifier is necessary on methods that override protected methods from a base class, without exposing those members to the public.

In general, you could introduce a lot of unnecessary rules to outlaw implausible combinations (such as protected static), but it wouldn't help much. You can't outlaw stupidity.