Library Management System

Console-based Java app showcasing clean layered architecture, the repository pattern, and JSON persistence.

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Project Preview

A layered Java console application built around clear separation of concerns: business logic lives entirely in the service layer, persistence is abstracted behind repository interfaces, data is stored as JSON with atomic, crash-safe writes, and every failure path raises a typed, predictable exception instead of a generic error.

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Project Stats

Metric	Details
Java Classes	33+
Architecture Layers	6
Custom Exceptions	7
Service Classes	4
Build System	Maven
Persistence	JSON (Jackson)

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What This Project Demonstrates

• Strict layered architecture — dependencies only ever flow downward
• Repository pattern — swap JSON for a database with zero service-layer changes
• Atomic, crash-safe JSON writes (temp file → rename, never partial writes)
• Centralized validation + a typed, unchecked exception hierarchy
• Real ISBN-10/13 checksum validation, not just format matching
• Business rules (loan period, fine rate) externalized to a properties file

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Quick Features

• ✅ Book Management — add, update, delete, search
• ✅ Member Management — register, search, track status
• ✅ Issue Book — eligibility checks + due-date calculation
• ✅ Return Book — atomic return with automatic fine calculation
• ✅ Statistics Dashboard — live active / overdue / most-borrowed metrics
• ✅ Report Export — timestamped .txt snapshots

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Architecture

ConsoleUI → Services → Repositories → JSON Storage — one-directional, interface-bound dependencies. Model, Utility, and Exception layers cut across all three.

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Core Workflows

Add-Book Flow

Book Input → Validation → Repository → books.json

Issue-Book Flow

Member Validation → Transaction Creation → Inventory Update

Return-Book Flow

Transaction Update → Fine Calculation → Inventory Restore

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Project Structure

Code is organized strictly by responsibility — model, exception, utility, repository, service, and UI each live in their own package. This separation of concerns keeps the layered architecture enforceable in practice, makes the codebase easy to navigate and maintain, and leaves a clear path to scale — such as swapping JSON for a database — without restructuring existing layers.

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Screenshots

Main Menu	Issue Book

Return Book	Statistics Dashboard

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Installation

Prerequisites: Java 17+, Maven 3.8+

git clone https://github.com/PawanChoudhary0607/Library-management-system.git
cd library-management-system
mvn clean install
mvn exec:java

Seed data is included — runs immediately after cloning.

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Recruiter Highlights

• Clean Architecture — strict separation between presentation, business logic, and persistence
• Repository Pattern — storage swappable without touching service or UI code
• OOP Principles — encapsulated entities with controlled state transitions
• SOLID Design — dependency inversion enforced at every repository boundary
• JSON Persistence — Jackson-based, atomic, crash-safe writes
• Exception Handling — typed, unchecked hierarchy with consistent error messages
• Maven Project Structure — standard layout, ready for build, test, and packaging

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Future Improvements

• Database integration (PostgreSQL / SQLite)
• Spring Boot migration
• REST API development
• Authentication & authorization
• Web dashboard
• Cloud deployment

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Pawan Choudhary · B.Tech CSE (AI/ML) GitHub Linkedin