Summary of Class Diagram

In this session, you understood the concept of class diagrams, which are used to show what classes will be present in the system and how they will interact with each other. You also learnt about class, which is just a blueprint to create objects of that type. Each class has attributes and methods. The class name is written in the Upper Camel Case convention, while attributes and methods are written in the Lower Camel Case convention.

Then, you learnt about three different types of visibilities:

1. public (+): Such attributes and methods are visible to all.
2. private (-): Such attributes and methods are visible only to that class.
3. protected (#): Such attributes and methods are visible to that class and all its sub-classes.

Then you understood the concept of multiplicity, which can be used to represent an array of objects. You also learnt how to define default values and property strings for some attributes.

You saw that there can be four different types of relationship between classes:

1. Association: It represents a collaboration between different classes. It is the general form of the other three relationships.
2. Generalisation: It represents a parent-child relationship or an 'is-a' relationship between different classes.
3. Aggregation: It represents the 'has-a' relationship, in which part objects can survive without the whole object.
4. Composition: It represents the 'has-a' relationship, in which part objects cannot survive without the whole object.

Then, you saw how to represent constraints for different classes or relationships and how to write general notes or comments about classes and relationships.

At the end, you learnt about association class, which can be used to capture the properties of an association relationship.