Question

As shown in http://docs.oracle.com/javase/tutorial/java/IandI/override.html, Java does allow

1. Overriding an instance method by an instance method and
2. Hiding a static method by a static method

My question is why Java doesn’t allow hiding a static superclass method by an instance method. This could be done like this:

class Base {
    static void foo () {}
}

class Derived extends Base {
    void foo () {}
    void access () {
        foo ();
        Base.foo ();
    }
}

I don’t see any particular issue with the above approach – it is only as “messy/complex” as the (allowed) hiding of statics already is.

Answer 1

I suspect it is to avoid confusion with dealing with the base class. In fact I imagine the designers didn’t see an obvious way this should behave.

class Base {
    static void foo () {}
}

class Derived extends Base {
    void foo () {} // say this compiled
}

Base b = new Derived()
b.foo(); // should the static or the virtual method be called?

Should b.foo() call Base.foo() or should it potentially call Derived.foo()?