State diagram (UML)

Example UML State diagram.

The state diagram in the Unified Modeling Language is essentially a Harel statechart with standardized notation^[1] ,^[2] which can describe many systems, from computer programs to business processes. In UML 2 the name has been changed to State Machine Diagram. The following are the basic notational elements that can be used to make up a diagram:

• Filled circle, representing to the initial state
• Hollow circle containing a smaller filled circle, indicating the final state (if any)
• Rounded rectangle, denoting a state. Top of the rectangle contains a name of the state. Can contain a horizontal line in the middle, below which the activities that are done in that state are indicated
• Arrow, denoting transition. The name of the event (if any) causing this transition labels the arrow body. A guard expression may be added before a "/" and enclosed in square-brackets ( eventName[guardExpression] ), denoting that this expression must be true for the transition to take place. If an action is performed during this transition, it is added to the label following a "/" ( eventName[guardExpression]/action ).
• Thick horizontal line with either x>1 lines entering and 1 line leaving or 1 line entering and x>1 lines leaving. These denote join/fork, respectively.

References

See also

• UML state machine

External links

Wikimedia Commons has media related to State diagrams.

• Current UML Specification by Object Management Group (OMG)
• UML 2 State Machine Diagrams

Unified Modeling Language
Actors	Organizations Object Management Group UML Partners Persons Grady Booch Ivar Jacobson James Rumbaugh
Concepts	Object oriented Object-oriented programming Object-oriented analysis and design Object-oriented modeling Structure Actor Attribute Artifact Class Component Interface Object Package Profile diagram Behavior Activity Event Message Method State Use case Relationships Aggregation Association Composition Dependency Generalization (or Inheritance) Extensibility Profile Stereotype Other Multiplicity
Diagrams	Structure Class Component Composite structure Deployment Object Package Behaviour Activity State Machine Use case Interaction Communications Sequence Interaction overview Timing
Derived languages	Systems Modeling Language (SysML) UML eXchange Format (UXF) XML Metadata Interchange (XMI) Executable UML (xUML)
Other topics	Glossary of UML terms Rational Unified Process Comparison of UML tools UML colors