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This article shows you how to understand the UML activity diagram, the content is concise and easy to understand, it will definitely brighten your eyes. I hope you can get something through the detailed introduction of this article.

UML activity diagram

An activity diagram is a representation of the activity view (figure 7-1). It includes some convenient shorthand symbols that can be used for virtually any state diagram, although the mixed representation of activity and state diagrams is ugly most of the time.

The active state is represented as a rectangle with a circular edge, which contains a description of the activity (the normal state box is a straight fillet). The simple completion of the conversion is indicated by an arrow. The branch represents the guardianship condition of the transformation or a diamond with a multi-marked exit arrow. The bifurcations and combinations of the controls are the same as those in the state diagram, and are multiple arrows that enter or leave the dark synchronization bar. Fig. 7 Mel 1 shows a UML activity diagram for order processing.

Figure 7-1UML activity diagram

To represent a scenario in which an external event must be included, the reception of the event can be represented as a converted trigger or a special embedded symbol waiting for a signal. Sending can also be expressed. However, if there are many event-driven transitions, it is preferable to use a common state diagram.

1. Swimming lane

It is often useful to organize activities in the model according to their responsibilities. For example, you can organize all the activities handled by a business organization. This allocation can be represented by organizing activities into different areas separated by lines. These areas are called swimming lanes because of their appearance. Figure 7. Mui 2 shows the swimming lane.

Figure 7 color 2 swimming lanes and object flow

two。 Object stream

UML activity diagrams can represent the value flow and control flow of objects. The object flow state represents the input or output objects in the activity. For the output value, the dotted arrow points from the activity to the object flow state. For input values, the dotted arrow points to the activity from the object flow state. If the activity has more than one output value or subsequent control flow, the arrow is directed back to the bifurcation symbol. Similarly, multiple input arrows point to the union symbol.

UML activity diagrams and other diagrams

The activity diagram does not show all the details of the calculation process. They represent the process carried out by the activity but do not indicate the object to which the activity is executed. Activity diagram is the starting point of design work. In order to complete the design, each activity must be extended and subdivided into one or more operations, each assigned to a specific class. The result of this allocation leads to the design work of the involution agreement used to implement the activity diagram.

The above is how to understand UML activity diagrams. Have you learned any knowledge or skills? If you want to learn more skills or enrich your knowledge reserve, you are welcome to follow the industry information channel.

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