See the following example:

interface I {}

class A implements I {}

class B implements I {}

class Foo{
    void f(A a) {}
    void f(B b) {}
    static public void main(String[]args ) {
        I[] elements = new I[] {new A(), new B(), new B(), new A()};
        Foo o = new Foo();
        for (I element:elements)
            o.f(element);//won't compile
    }
}

Why doesn't overloading methods support upcasting?

If overloading was implemented at run time, it would provide much more flexibility. E.g, the Visitor Pattern would be simpler. Is there any technical reason that prevents Java from doing this?

java overloading language-design
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