How to model two interacting state machines of two different classes?

Question

As far as I know, UML state machines model the behavior of one element, for example the behavior of one class.

I wonder how to model state machines with two classes which interact.

The state of one class depends on the state of the other class and transition of one state machine may trigger transition of the other state machine.

Do I have to use UML effect? Could an UML effect of one state machine trigger a transition of another state machine?

Answer 1

You can send events between classes to trigger transitions, something like this, for example:

---