2.5. Understanding Class Diagrams

The concepts of classes and objects are fundamental to OOP. An object is a structure for incorporating data and the procedures for working with the data. These objects implement the functionality of an object-oriented program. Think of a class as a blueprint for the object. A class defines the structure and the methods that objects based on the class type will contain.

Designers identify a potential list of classes that they will need to develop from the SRS and the use case diagrams. One way you identify the classes is by looking at the noun phrases in the SRS document and the use case descriptions. If you look at the documentation developed thus far for the airline booking application, you can begin to identify the classes that will make up the system. For example, you can develop a Customer class to work with the customer data and a Flight class to work with the flight data.