Adding change events to state machine diagrams

In UML models, a change event is an event that represents a condition. The condition is defined by a Boolean-valued expression that triggers a transition when its value changes from false to true.

Before you begin

Before you can add a trigger to a transition, you must have a state machine diagram open in the Modeling perspective.

About this task

To add a change event to a transition:

Procedure

  1. Right-click a transition; then click Add UML > Trigger > Change Event.
  2. Complete one of the following steps:
    • To create a new change event, click Create Change Event, type a name, and press Enter.
    • To select an existing change event, click Select Existing Element, and in the Select Element window, click a change event, and click OK. Type a name and press Enter.

Results

The change event is added to the transition in the diagram and in the Project Explorer view. You can view and modify details about the change event in the Properties view, on the Triggers page for the selected transition.

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