Lecture Notes - Week 3

Introduction

• Good morning everyone.
• We are officially entering week 3 of the course.
• By now, students should be familiar with the software and class structure.

Recap of Weeks 1 & 2

• Topics covered:
  • Procedural vs. Object-Oriented Programming
    • Focus on Object-Oriented Programming (OOP) for the current unit.
  • Key Concepts of OOP:
    • Objects:
      • Contain attributes (data/fields).
      • Perform methods (behaviors).
    • Classes:
      • Template for creating objects.
      • Must contain a constructor.
  • Constructor:
    • Same name as the class, no return type.
    • Used to create an object from the class.
  • Properties:
    • Access private fields of a class.
    • Important for encapsulation.
  • Methods:
    • Can have return types or be void (no return).

Unit Testing

• Importance of unit tests to verify methods in a class.
• Use of NUnit framework for testing in C#.
• Essential packages to add for testing:
  • nunit.framework

Week 3 Focus: Object Collaboration

• Learning about object collaboration in solving complex problems.
• Example: Building a Monopoly Game
  • Identify main objects:
    • Die, Monopoly Game, Board, Player, Piece, Square.
  • Emphasizes multiple classes working together.
  • Relationship types between classes:
    • Association
    • Aggregation
    • Dependency

Class Diagram

• High-level view of class relationships.
• Example classes for Monopoly Game and their relationships.

Relationship Types

1. Association:
   • Described as "has a" relationship (e.g., Instructor teaches Students).
   • Represented by a straight line.
2. Aggregation:
   • "Is a part of" relationship.
   • Types:
     • Shared Aggregation:
       • Parts can exist independently (e.g., players in a team).
     • Composition:
       • Parts cannot exist without the whole (e.g., engine in a car).
3. Dependency:
   • Describes usage (e.g., Player uses Die).
   • Represented by a dashed arrow.

Class Diagram Notation

• Rectangle for class, divided into three segments:
  1. Class name
  2. Attributes
  3. Methods
• Access modifiers:
  • Public: +
  • Protected: #
  • Private: -

Examples of Relationships

• Person & Passport:
  • Analysis leads to a potential dependency relationship.
• House & Room:
  • Composition relationship.
• Airplane & Passenger:
  • Shared aggregation or association based on context.

Coding Examples

Course and Unit Classes

• Unit Class:
  • Fields: Code, Name, Available.
  • Methods: Constructor, Print Details.

List vs. Array

• Differences:
  • Array: Fixed size, cannot be resized.
  • List: Dynamic size, can grow/shrink as needed.
• Example code for creating and managing lists in C#.

Unit Testing in C#

• Process of setting up unit tests:
  1. Setup objects to test.
  2. Execute methods.
  3. Check results.
• Example tests for adding/removing units from a course.

Summary

• This week focused on understanding relationships between classes and object collaboration.
• Importance of using the right relationship type based on the scenario.
• Continuous practice and reviewing of previous weeks recommended.

Questions & Conclusion

• Students encouraged to ask questions for clarity.
• Reminder to review submissions and ensure all requirements are met.