Class Diagrams
Last updated
Last updated
PLEASE NOTE: We will revisit Class Diagrams in Term 2, so DO NOT worry too much about understanding them yet! There are NO ACTIVITIES here.
Class diagrams provide a visual representation of systems that are implemented using the object-oriented paradigm. They model classes, their attributes and methods, and the relationships between classes.
In software engineering, class diagrams are essential tools for planning and understanding the structure of an application. They help developers and stakeholders visualise how different components of a system interact and how data flows between these components.
A class diagram typically consists of several classes, each represented as a rectangle divided into three sections: the top section contains the class name, the middle section lists the attributes (or properties) of the class, and the bottom section shows the methods (or functions) that operate on the attributes.
The relationships between classes in a class diagram are depicted using various types of lines, each representing a different type of relationship. These relationships help developers understand how objects in the system are connected, how they interact, and how changes in one class may affect others.
By using class diagrams, developers can effectively plan and communicate the structure of a software system, ensuring that all team members have a shared understanding of the system's architecture. They are not only useful during the design phase but also serve as valuable documentation that can be referred to throughout the software development lifecycle. This helps in maintaining the system, extending its functionality, and onboarding new team members.
In the above school management system:
Each Person has the attributes firstName and lastName, and the printFullName() method will display these.
Both a Student and Parent will inherit attributes from Person (parents and students all have full names).
Each Parent has an occupation and information on whether they are alumni (true/false).
Each Student has a studentID and a homeroom. Each student can be enrolled into a class with the enrolClass() method.
Each Subject has 1 or more studentIDs and a subjectName. Each subject can display the list of students with the printStudentList() method.
Each Student has 1 or more Subjects.
Each Subject has 0 or more Students.
