How to give two different classes the same interface?

Question

Can I give 2 different classes (that I cannot modify as they are autocreated webservice classes) the same interface?

Problem: I have several autocreated webservice classes, that have a method with the same signature. But as the classes have no common interface, I cannot group them and thus cannot call both of them from a single method.

Example:

class A {
  void sameMethod();
}
class B {
  void sameMethod();
}


class MyService() {
  //I cannot do the following as I cannot group A and B with the same interface
  void callAorB(<Class A or B> object) {
     object.sameMethod();
  }
}

Will it still be somehow possible to just execute òbject.sameMethod() even though I cannot make a common reference between class A and class B`?

Answer 1

If you can't modify the classes then no, you can't force the interfaces onto the objects. You can however create an interface and two adapters which implement this interface.

Answer 2

The hacked solution would be:

if(object instanceof A)
   ((A)object).sameMethod();
else if(object instanceof B)
   ((B)object).sameMethod();

but if you can make them implement an interface would be much better