Like a state diagram, an activity diagram models aspects of system behavior. Unlike a state diagram, an activity diagram models an object’s workflow (sequence of events) during program execution. An activity diagram models the actions the object will perform and in what order. Recall that we used UML activity diagrams to illustrate the flow of control for the control statements presented in Chapters 4 and 5.
Figure 22.14 models the actions involved in executing a
BalanceInquiry transaction. We assume that a
BalanceInquiry object has been initialized and assigned a valid account number (that of the current user), so the object knows which balance to retrieve. The diagram includes the actions that occur after the user selects ...