State Machine Diagrams
Each object in a system goes through a series of discrete states. An object’s current state is indicated by the values of the object’s attributes at a given time. State machine diagrams (commonly called state diagrams) model key states of an object and show under what circumstances the object changes state. Unlike the class diagrams presented in earlier case study sections, which focused primarily on the structure of the system, state diagrams model some of the behavior of the system.
Figure 22.13 is a simple state diagram that models some of the states of an object of class
ATM. The UML represents each state in a state diagram as a rounded rectangle with the name of the state placed inside it. A solid circle with an attached ...