Open the UML model diagram that contains the UML element for which you want to create an activity diagram. In the tree view (tree view: Displayed in a window in the UML Navigator, a hierarchy in which each UML element or view (diagram) is represented by an icon. The UML template automatically creates a tree view of your model.), right-click the icon for the package, subsystem, class (class: In a static structure diagram, a set of objects with similar structure, behavior, and relationships. Classes are declared in class (static structure) diagrams and represent concepts in the systems being modeled.), operation, or use case (use case: In a use case diagram, a representation of a set of events that occurs when an actor uses a system to complete a process. Normally, a use case is a relatively large process, not an individual step or transaction.) in which you want to create an activity diagram (activity diagram: A special case of a statechart diagram in which all of the states are action states and the transitions are triggered by the completion of actions in the source state.). Point to New, and then click Activity Diagram.
A blank page appears, and the UML Activity stencil becomes the top-most stencil. The workspace displays 'Activity' as a watermark. An icon representing the diagram is added to the tree view.
If you want to indicate responsibility in the activity diagram, drag a Swimlane shape onto the page for each class, person, or organizational unit you want to represent.
Create swimlanes in an activity diagram
Drag an Action State or State shape onto the drawing page for each action or activity state you want to represent. Use the Initial State and Final State shapes to represent initial and final pseudo states. Work with state shapes Connect Control Flow shapes to State shapes to indicate the change from one state to another.
Indicate the flow of control in an activity diagram
Use the complex transition shapes, Transition (Fork) or Transition (Join), to represent the forking of one action state into multiple parallel states, or the synchronization of multiple action states into one state. Work with transition shapes If you want to replace transition strings with signal icons, use the Signal Send and Signal Receipt shapes to represent the signals. Double-click any shape to open its UML Properties dialog box where you can add a name, transition string, guard condition (guard: In a statechart or activity diagram, a condition that specifies when an event can take place. Whenever its event fires, a guard is evaluated only once.), deferred events (deferred event: In a statechart or activity diagram, an event that must be deferred for later use while another activity is under way. You can show a deferred event for a state by including the event among the state's internal transitions.), and other properties.Save the diagram.