How do I represent subclass invocations in Activity Diagrams

Question

1. Class 1 creates Class 2 which is a subclass of class 3
2. Class 1 invokes a method on Class 2, which doesn't implement that method and instead hands it off to class 3
3. Class 3 then calls a method on Class 2

If I represent all 3 classes on the diagram, and then draw an arrow between class 1 and 3, it looks like 1 is directly invoking 3, which it isn't. However, I also don't want to make it look like Class 2 is implementing that method.

Answer 1

You have a fundamental error in your thought. SDs and ADs do not show classes, but instances. And there are only two instances here, namely that of Class1 and that of Class2 being a subclass of Class3 . So the internal call from Class2 's instance goes to itself.

The structure is like this:

And the SD like that:

In an AD it would look like this: