State diagrams enable you to model UML state machines. State machines depict the dynamics of a system or subsystem. They model the behavior of an object as it passes through different states in response to events that occur during its lifetime, including its response to events. A state is a condition during the life of an object (or interaction) during which it satisfies a condition, performs an action, or waits for an event.
State diagrams emphasize the possible states of an object and the transitions between states. You can use them to model the lifetime of an instance of a class, an instance of a use case, or even an instance of a system. During that period, the object can be exposed to different kinds of events to which it responds with some action, and the result of which is a change in its state.
Related Topics: