IB Computer Science - D.1.3 Construct UML diagrams

A.3 Construct UML diagrams

D.1.3 Construct Unified Modelling Language (UML) diagrams to represent objects

Abstraction

The act of representing essential features without including the background details or explanations. In computer science and software engineering domain, abstraction principle is used to reduce complexity and allow efficient design and implementation of complex software systems.

UML

- UML stands for Unified Modelling Language.
- UML is a way of visualizing a software program using a collection of diagrams.
- Classes represent an abstraction of entities with common characteristics.
- Associations represent the relationships between classes.

Benefits of class diagrams

- Illustrate data models for information systems, no matter how simple or complex.
- Better understand the general overview of the schematics of an application.
- Visually express any specific needs of a system and disseminate that information throughout the business.
- Create detailed charts that highlight any specific code needed to be programmed and implemented to the described structure.
- Provide an implementation-independent description of types used in a system that are later passed between its components.[3]

Basic components of a class diagram

The standard class diagram is composed of three sections:

- Upper section: Contains the name of the class. This section is always required, whether you are talking about the classifier or an object.
- Middle section: Contains the attributes of the class. Use this section to describe the qualities of the class. This is only required when describing a specific instance of a class.
- Bottom section: Includes class operations (methods). Displayed in list format, each operation takes up its own line. The operations describe how a class interacts with data.[3]

Member access modifiers

All classes have different access levels depending on the access modifier (visibility). Here are the access levels with their corresponding symbols:

public (+)

private (-)

protected (#)

derived (/)

package (~)

UML Class Diagram Tutorial

UML Class Diagrams

How to make a class diagram

In Lucidchart, creating a class diagram from scratch is surprisingly simple. Just follow these steps:

1. Open a blank document or start with a template.
2. Enable the UML shape library. On the left side of the Lucidchart editor, click "Shapes." Once you're in the Shape Library Manager, check "UML" and click "Save."
3. From the libraries you just added, select the shape you want and drag it from the toolbox to the canvas.
4. Model the process flow by drawing lines between shapes while adding text.

Dive into this guide on how to draw a class diagram in UML for additional insight. In Lucidchart, it's easy to resize and style any element. You can even import SVG shapes and Visio files for a custom solution.

If you'd like to learn more about UML, check out our tutorial, "What Is UML?"

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