Showing an association between an activity and a class on a class diagram
A Class Diagram can show a Uni-directional Association between an Activity and a Class (or a Class subtype). The Association represents an object node (Data Store, Central Buffer, Input Pin or Output pin) that uses the Class as its type and is owned by the Activity. As such, when you select the Association on the Block Definition Diagram, the Property Pages show the properties of the object node.
To show an association between an activity and a class on a class diagram:
1. Add the Activity and Class to a Class Diagram.
2. On the diagram's toolbar, click the Uni-Directional Association button.
3. Click the Activity, and then click the Class.
4. If a popup menu appears, click the command for the object node you want to show.