Class Diagram Example: File Output (Use of Generalization)


This is a simple class diagram that shows the classes used in a file output procedure. Such a class diagram exposes classes under a particular context instead of showing all the classes. This makes the representation clearer and easier to understand.

Draw your Class diagram by using this one as a starting point. Simply Click Use this Template to edit, or click Create Blank to draw from scratch.

What is Class Diagram?

Class diagrams still represent by far the most important and widely used modeling technique of UML. A class diagram is a static model of a system which shows the structure of the software in terms of the constituent classes and how each class is related to other classes. A class diagram gives a static view of the system. As opposed to a dynamic view, which describes what the software does when it runs, a class diagram provides a static view, which describes the classes that make up the software. Class Diagrams can also be used to generate source code for system implementation.

Guidelines for creating Class Diagram?

  1. Identify classes
    • a. From domain analysis such as textual analysis
    • b. From CRC cards
    • c. From use case description
    • d. From sequence diagram or use case scenarios
  2. Give analysis a name and a brief description which could be done through terms and glossary
  3. Structure classes in the right places of the diagram and related them with simple relationships
  4. As the development move forward, detail the class with attributes and operations, this often done in conjunction with use case and sequence diagrams
  5. Refine the class diagram with inheritance for future reuse
  6. Elaborate the details which is helpful for implementation such as accessibility, rules, constraints and etc.
  7. Put related classes into packages to form your software architecture

Why do we need Class Diagram?

Class diagrams are useful in many stages of system design:

  1. Analysis stage - a class diagram can help you to understand the requirements of your problem domain and to identify its components.
  2. Design stage - you can refine your earlier analysis and conceptual models into class diagrams that show the specific parts of your system, user interfaces, logical implementations, and so on.v
  3. Detailed design stage - the class diagrams that you create during the early stages of the project contain classes that often translate into actual software classes and objects when you write code.v
  4. Implementation stage - you can use class diagrams to convert your models into code and to convert your code into models.

Your class diagrams then become a snapshot that describes exactly how your system works, the relationships between system components at many levels, and how you plan to implement those components.

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