Fundamental UML Concepts

Attributes

Properties or data of a class (e.g., name, age).

Operations = Behaviour

Functions or methods that define what a class can do (e.g., calculateSalary()).

Class

A blueprint for creating objects.

Objects = Instance

A specific object created from a class blueprint.

Association

A relationship between two classes (e.g., a Teacher is associated with a Student).

Inheritance

A class (child) inherits properties and methods from another class (parent).

Realization

A class implements an interface, providing concrete behavior for the methods defined in the interface.

Dependency

One class depends on another for some functionality, often represented by a dashed line.

Aggregation

A 'whole-part' relationship where the part can exist independently (e.g., Library has many Books).

Composition

A stronger form of aggregation where the part cannot exist without the whole (e.g., House has Rooms).

Role

The role that an object plays in a relationship (e.g., Teacher plays the role of Instructor).

Multiplicity

Specifies how many objects of one class can be associated with objects of another class (e.g., 1..* means one to many).

Generalisation

The process of extracting common features from multiple classes into a general, higher-level class (similar to inheritance).

Abstract Class

A class that cannot be instantiated on its own and is used as a base for other classes.

Operation

A method or function that defines behavior within a class.

Encapsulation

Hiding the internal details of a class and exposing only necessary functionality (e.g., using private and public access modifiers).

Signature

The declaration of an operation, specifying its name, parameters, and return type (e.g., int calculateSalary(int hoursWorked)).