Why doesn't Java allow hiding static methods by instance methods?

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()?

Answer 2

Simple answer: that would be the mess.

Concrete answer: what to call in that case Derived.foo()? Base.foo() can't be called as it's hidden (as per you), Derived.foo() can't be called as it's not static.

Answer 3

Because, one are like Bananas and the other ones are Apples.

Explaination:

• Static Methods are created when reading the Class-Structure
• Methods are created when a object of a class is created.

Example:

Foo.bar();

is something different than

new Foo().bar();

Guess which one is called?

Foo f = new Foo();
f.bar();

Answer 4

Another to add here is: 1. Static methods belong at the class level. So u cannot override method in the derived class. as simple its called hiding. :) 2. Instance methods belong to the objects, so objects are overrided. So we can override in the derived class.

Above other comments give a good example have a look into it..

Regards Punith