Library Management System - Deliberately Smelly Code

This project demonstrates a functional Library Management System written in Java with intentionally implemented code smells for educational purposes.

Project Structure

Assignment 2/
├── src/
│   ├── main/java/
│   │   ├── Book.java                 # Book entity class
│   │   ├── Member.java               # Member entity class  
│   │   ├── LibrarySystem.java        # Main system class (God Class)
│   │   ├── MemberValidator.java      # Utility class with Feature Envy
│   │   ├── BookUtilities.java       # Utility class with duplicated code
│   │   └── Main.java                 # Main class with demo and tests
│   └── test/java/
│       └── LibrarySystemTest.java    # Comprehensive unit tests
└── docs/
    └── smells.md                     # Documentation of code smells

Features

• Add and manage books in the library
• Add and manage library members
• Borrow and return books with due date tracking
• Search books by title, author, or ISBN
• Member validation and risk assessment
• Fine calculation for overdue books
• Transaction history tracking
• Comprehensive unit testing

Code Smells Implemented

1. Long Method - borrowBook() method in LibrarySystem.java
2. God Class (Blob) - LibrarySystem class handles too many responsibilities
3. Duplicated Code - Validation logic repeated in multiple places
4. Large Parameter List - validateMemberForBorrowing() method
5. Magic Numbers - Hardcoded values throughout the codebase
6. Feature Envy - Utility classes overly interested in other classes' data

How to Run

Compilation

cd "src/main/java"
javac *.java

Execution

java Main

The program will:

1. Demonstrate library functionality
2. Show borrowing and returning processes
3. Display search results
4. Run 8 comprehensive unit tests
5. Show 100% test success rate

Code Statistics

• Total Lines of Code: ~679 lines (including Main.java with tests)
• Core System Code: ~526 lines (excluding Main.java)
• Test Coverage: 8 unit tests covering all major functionality
• Success Rate: 100% (all tests pass despite code smells)

Learning Objectives

This project demonstrates that:

• Code can be functional while still having poor design
• Code smells make maintenance and extension difficult
• Proper refactoring would improve code quality significantly
• Unit tests can validate functionality even with smelly code

See docs/smells.md for detailed documentation of each code smell with file locations and justifications.