Question

What is it called when trying to overload a function based purely on the return type?

ie:

Public String DoWork()

Public int DoWork()

You cannot do the above, right?

Is that called covariance?

Answer 1

No, covariance refers to changing the return type when overriding not overloading.

From wikipedia

 class A {
 }

 class B extends A {
 }

 // Classes demonstrating method overriding:

 class C {
     A getFoo() {
         return new A();
     }
 }

 class D extends C {
     B getFoo() {
         return new B();
     }
 }