UML Weekend Crash Course™ - To Parent Directory

Session 20—Modeling the Dynamic View: The Statechart Diagram 209
Prospect
order placed/ addOrder(Order)
Active
[payment past due]/
setProbation(true)
On Probation
[6 months' orders > $10,000]/setPreferred(true)
[payment past due > 1]/setPreferred(false)
Preferred
Figure 20-11 Adding the fourth transition
This Statechart did not have a final state because within the scope of the problem statement
there is no time when a customer object can no longer change. “On Probation” might
be a final state because there are no arrows coming out of it, but this happened only
because of the limited size of the example.
There is one more very important observation about events on a Statechart diagram. The
absence of an event is almost as informative as the presence of an event. In Figure 20-11,
the only events that cause a Customer to change from the active state are the conditions
6 months’ orders > $10,000, and payment past due. Even though you modeled the event
order placed in another location, it has no effect when it happens to the Customer while he
is in the active state. It simply is not recognized by the active state. You know this because
there is no arrow leaving the active state in response to the order placed event. So the diagram
reveals both the events that an object will respond to while in a state and the events
it will not respond to.