UML - Activity Diagram Tutorial
Activity diagrams may seem confusing, but with the right resources, you can make them all on your own. Follow these detailed instructions to learn how.
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How to Make Activity Diagrams
To begin our UML activity diagram tutorial, we'll start with the basics. Make sure you understand what an activity diagram is. You may even want to review what UML is, so you fully understand the language that activity diagrams use as a guide. When you're prepared with the necessary tools—including a diagramming program like Lucidchart—it's time to get started.
LIST PROCESS STEPS
Decide which business or computational process you want to model. Then write down each step that occurs in that process. Activity diagrams can help you:
- Model the workflow of a software system
- Analyze a use case by describing and timing the necessary actions
- Illustrate a complex sequential algorithm
- Describe applications with parallel processes
ADD SHAPES AND SYMBOLS
Begin your chart with a start symbol—a black circle. Then you can drag out activity shapes; just double-click the shape to add descriptive text. In Lucidchart, all symbols can be dragged from the toolbox to the canvas.
Add symbols as your process requires and use connectors to show the flow of each activity as it ends and begins. We've listed the most common symbols below, along with their meanings. If you're still confused, check out this comprehensive guide to activity diagram symbols.
Activity nodes, also known as activity states, represent a single step within a workflow.
Transitions are simply connecting lines that demonstrate which activity node follows another.
Decisions are represented with diamond shapes. They show alternative threads in the workflow.
Synchronization bars are used to model parallel subflows. These thick vertical or horizontal lines allow you to show concurrent threads in a process.
REVIEW THE FLOW
To ensure that you're demonstrating the important steps in your activity, consider questions like:
What happens when this process is initiated? How does the process complete itself?
How does one activity affect other steps in the workflow, organization, or system?
When do other factors and people enter the flow? Which options or new paths do they provide?
When you've covered these questions, ask your team members to review the finished document. They may be able to provide a unique perspective that ultimately improves understanding.
With Lucidchart, it's easy to create effective activity diagrams, use case diagrams, sequence diagrams, and more. Start a free trial and see for yourself.