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UML Activity Diagram: A Complete Guide

> Edraw Knowledge > UML Activity Diagram: A Complete Guide
Posted by Daniel Belisario | 01/27/2021
There is a complete guide on UML activity diagrams. They are usually used in software or system development and seem to be more complicated than basic flowcharts.

What are UML activity diagrams?

UML (Unified Modelling Language) Activity Diagrams are used to illustrate how actions flow in a system while referring to its steps during the execution. The focus is on how events around the steps create a smooth workflow.

Website UML Sequence

These diagrams come in 2 types:

  • Structure diagrams
  • Behavioral diagram

A UML activity diagram is, in this case, a behavioral diagram. It is because the general UML diagram depicts the system's behavior in the decision-making process as it responds to events surrounding the steps involved.

These activity diagram tools are standard in business and engineering environments as they all work with systems.

What do we use activity diagrams for?

You'll meet activity diagrams in various corporate structures and engineering fields of expertise. They are very useful:

  • Understanding a system's functionalities
  • In this case, a method is illustrated with its components labeled as objects for study. The flow from one point to another is also indicated. Through such, you will be able to gain insight into how, for example, various departments relate

    Your purpose here could be to establish certain managerial concepts and how to complement or improve them. Even in engineering designs, the use of activity diagram examples gives you the benefit of having full control over a system's efficiency.


  • Predetermining future outcomes
  • You can use an activity diagram to look into the work prospects. As you take note of all the possible outcomes, you will be able to make present decisions more effectively.

    It also has an added advantage of giving you the capacity to make more realistic goals that are both inexpensive and achievable.


  • Strategizing
  • Because of competition, the strategy has become a pivotal component to the growth and survival of a business or sustenance of a project. With an activity diagram, you can get the upper hand.

    A UML activity diagram can be used to showcase key components of your environment and how they possibly relate, and you can then use the information to enhance your advantages. From this, both analysts and stakeholders will be able to draw reliable conclusions.


  • Identifying a system's requirements
  • Where a system seems slow, faulty, or needs an upgrade, looking at an activity diagram will show you any possible gaps that may need restructuring. These could be in hierarchical management or responding time, for example, in emergency cases.

Activity Diagram Notations

Take a look at an activity diagram, and you'll find a variety of symbols. Just like with every layout, these symbols are called notations. The basic components include:

  • The Initial state
  • In every process, there is a point of origin. Where it all starts in the activity diagram is marked by a plain circle.

  • The Action
  • Action is an activity. When executed or rather triggered, there is a systematic roll of events that follow. All these are the actions and get represented by round-edged rectangles.

  • A decision state
  • It is the point at of decision and is generally indicated by a diamond shape to symbolize the possibility of taking various directions in the decision-making process. There's usually input and output.

  • Flow Controls
  • Also known as connectors, these indicate the flow in-between steps in the activity diagram.

  • The Final state
  • It is the final step in the flow of an activity diagram. A circle with an outline represents it.

Let's look at these notations and their meanings.

Activity Diagram Notations

Classic activity diagram examples

With the symbols mentioned above, you can also create your activity diagrams. But first, let us look at some examples to illustrate in what cases you can use the symbols above.

  1. Phone use process
  2. Phone UML Activity Diagram

    Above is a diagrammatic illustration of what steps to take as a new beginner when using your phone for the first time. The initial state represents a phone that is off. Then you have to turn it on and enter your Sim Pin. If it lacks a sim card, then you'll have to switch it off and insert it.

    However, where all is well, you'll smoothly go into the locked screen and you can swipe to access applications on your phone. It is the final state.

  3. Shopping order process
  4. Shopping Order UML Activity Diagram

    The shopping order processing above shows how to deal with an order. When it's rejected, the order will be closed. Besides, the bar represents actions that you can do simultaneously. When it's accepted, you have to fill it first, and after that, you can ship the order and send an invoice. When the order closes, the transaction is complete.

  5. ATM Withdrawal Process
  6. ATM Withdrawal UML Activity Diagram

    When you go to withdraw cash from an ATM, three parties will be involved, including the customer, ATM, and the bank. The ATM coordinates with the bank at various points to make the process of transaction smooth.

    The initial state is the customer to start the session. The diagram displays both physical and invisible interactions until the customer gets the cash.

  7. Laptop Sale Process
  8. Laptop Sale UML Activity Diagram

    When you have a laptop and use it, it goes through the process of being made, tested, and sold. But in the diagram, you can see that some laptops failed to pass tests and then need testing once more.

    During tests, the laptop can break down completely. In this case, it will be taken back to the factory for a remake. Also, when you use it, accidents usually happen and you need to replace the parts.

    You must have realized the use of broken arrows. As illustrated above, they symbolize the flow of an object as it passes from one point to another.

How to create an activity diagram?

The diagrams above are all made from Edraw Max. So, what are the steps to follow?

Step 1: Launch Edraw Max. Select the blank page and click on Create to open a drawing page.

Open Edraw Max

Step 2: Click the arrow on the library icon. A drop-down list of various symbols appears.

Open Edraw Max Library

Step 3: Each category has a subcategory that shows on the right. Inspect the subcategories until you find what you need.

Step 4: Symbols appear on the left panel. Drag and drop them into your drawing page. To edit labels, double-click on the symbol.

Step 5: Customize symbols on the right sidebar. Click on any option to open a panel, you'll see a selection of adjustments you can make.

Open Edraw Max Fill Panel

Step 6: Use the necessary arrows to connect your UML symbols.

Step 7: Save your diagram. Edraw Max allows you to save files in local disk or on the cloud. However, for the cloud option, you'll need to sign in at first.

Summary

For your designs or projects, Edraw Max will be your go-to activity diagram creator. The software certainly has rich tools and abundant examples for free use. And the MS Word-like interface will make you feel at ease.


Furthermore, Edraw Max has its software working to enhance teamwork cooperation. If you belong to a prominent organization, it is the perfect tool to introduce. Share Edraw Max with your colleagues. Your productivity will never be the same again as it will boost uprightly.

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