Today we focused on elevating our Library Management System to production-grade quality, with emphasis on proper domain modeling and clean architectural principles.
The code changes from this session can be found here.
Day 2 Summary
Overview
Restructured the Library Management System into a production-grade application with proper domain modeling, error handling, and service architecture.
Environment & Architecture
- Organized codebase into clear packages:
- Domain entities
- Custom exceptions
- Service layer
- Utilities
Concepts Covered
Domain Modeling
- Refined core entities
- Introduced physical copy management
- Implemented repository pattern
- Separated immutable and mutable state
Error Handling
- Created proper exception hierarchy
- Implemented state-based error handling
- Added descriptive error messages
Collections and State Management
- Efficient storage structures
- Copy identification system
- Stream operations for data access
- Protected state transitions
Design Patterns
- Repository Pattern
- Service Layer
- Interface segregation
- Immutable value objects
Key Takeaways
- Clean architectural boundaries
- Robust error handling
- Type-safe operations
- Clear separation of concerns
Next Steps
Ready to explore:
- Lending periods
- Author entity
- Search improvements
- Reservation system
Master’s Reflection
The apprentice demonstrated exceptional intuition for clean architecture, consistently questioning and improving the design. Their willingness to eliminate unnecessary abstractions, as shown with the Book class removal, reveals a growing mastery of simplicity in design. The methodical approach to package structure and error handling suggests a promising path ahead in the journey of Java mastery.