LibraNet - A Java Library Management System

Project by E. Jagadeeswar Patro
Date: September 19, 2025

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📜 Table of Contents

• 📖 Overview
• ✨ Core Features
• 🏗️ Project Architecture & Design Choices
• 📁 Folder Structure
• 🛠️ Technologies Used
• 🚀 Setup and Running the Project
• 📸 Application Showcase
• 🔮 Future Improvements

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📖 Overview

LibraNet is a command-line application designed to simulate the backend system for an online library platform. This project was developed as a solution to a technical challenge focused on demonstrating core Object-Oriented Programming (OOP) principles, including abstraction, inheritance, and polymorphism. The system manages various types of library items, handles core operations like borrowing and returning, and provides a robust, extensible, and reusable class structure.

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✨ Core Features

• Object-Oriented Design: Utilizes abstract classes and interfaces to create a clean, maintainable, and extensible architecture.
• Multiple Item Types: Manages Books, Audiobooks, and EMagazines, each with common attributes and specialized behaviors.
• Core Library Operations: Supports borrowing, returning, and checking the availability of items.
• Interactive Command-Line Interface (CLI): A user-friendly menu allows for dynamic interaction with the library catalog.
• File System Integration: Can open associated media files (.pdf, .mp3) using the system's default applications.
• Robust Error Handling: Gracefully handles invalid user input in the CLI to prevent application crashes.
• Unit Tested: Core business logic is verified with a suite of JUnit 5 tests to ensure reliability and correctness.

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🏗️ Project Architecture & Design Choices

The architecture is designed for reusability and future growth. The class diagram below illustrates the relationships between the core components.

---
config:
  theme: neo-dark
  look: handDrawn
  layout: elk
---
classDiagram
direction TB
    class LibraryItem {
        <<abstract>>
        #int itemId
        #String title
        #String author
        #boolean isAvailable
        #String filePath
        #LocalDate borrowDate
        #LocalDate dueDate
        +borrowItem()*
        +returnItem()*
        +isAvailable() boolean
        +openMedia()
        +getDueDate() LocalDate
    }

    class Playable {
        <<interface>>
        +play()*
        +getDuration() int*
    }

    class Book {
        -int pageCount
        +getPageCount() int
        +read()
    }

    class Audiobook {
        -int durationInMinutes
        +play()
        +getDuration() int
    }

    class EMagazine {
        -int issueNumber
        +archiveIssue()
        +read()
    }
    
    class Library {
        -Map~Integer, LibraryItem~ catalog
        +addItem(LibraryItem item)
        +findItemById(int itemId) LibraryItem
        +borrowItem(int itemId)
        +returnItem(int itemId)
        +displayAllItems()
        +calculateFine(int itemId) double
    }

    LibraryItem <|-- Book
    LibraryItem <|-- Audiobook
    LibraryItem <|-- EMagazine
    Playable <|.. Audiobook
    
    Library "1" *-- "many" LibraryItem : manages

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• Abstract Class: LibraryItem: This is the foundation of the design. It contains all the common properties (title, itemId, etc.) and behaviors (openMedia()) shared by every item. By making it abstract, we enforce a common structure and prevent code duplication.
• Interface: Playable: This contract defines a capability that can be shared across different types of media. Currently, only Audiobook implements it, but in the future, a VideoLecture class could also implement Playable without any changes to the core system. This makes the design highly extensible.
• Concrete Subclasses: Book, Audiobook, and EMagazine: extend LibraryItem and add their own specialized properties and methods (e.g., getPageCount()), demonstrating inheritance.
• Manager Class: Library: This class handles the high-level management of the item catalog. By using a Map, it provides efficient, ID-based lookups. It acts as the main point of interaction, separating the collection logic from the item logic itself.

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📁 Folder Structure

The project is organized into distinct source, test, and resource folders for clarity and maintainability.

LibraNet/
├── media/
│   ├── books/
│   ├── audiobooks/
│   └── emagazines/
├── src/
│   ├── LibraryItem.java
│   ├── Book.java
│   ├── Audiobook.java
│   ├── EMagazine.java
│   ├── Playable.java
│   ├── Library.java
│   └── App.java
├── test/
│   ├── LibraryTest.java
│   ├── BookTest.java
│   ├── AudiobookTest.java
│   ├── MagazineTest.java
└── README.md

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🛠️ Technologies Used

• Java (JDK 11+)
• JUnit 5 for Unit Testing

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🚀 Setup and Running the Project

Prerequisites

• Java Development Kit (JDK 11 or newer) installed.
• Visual Studio Code with the Extension Pack for Java installed.

1. Running the Interactive Application (CLI)

1. Clone this repository to your local machine.
2. Open the project folder in Visual Studio Code.
3. Navigate to src/App.java in the Explorer.
4. Click the "Run" button that appears above the main method.
5. The interactive menu will appear in the integrated terminal, ready for your commands.

2. Running the Unit Tests

1. Ensure the project has been configured for testing (see JUnit setup steps).
2. Navigate to test/LibraryTest.java in the Explorer.
3. Click the green "play" icon next to the public class LibraryTest line to run all tests.
4. The Test Explorer view will open and display the results. A successful run will show all tests with green checkmarks.

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📸 Application Showcase

Here are a few screenshots demonstrating the interactive command-line interface in action.

1. The Main Menu
The user is presented with a clear and comprehensive list of options.

2. Listing Items by Type
The application allows users to filter the library catalog by item type and then provides a streamlined option to open a file directly from the filtered list.

3. Borrowing & Returning an Item
Streamlined inventory management.

4. Fine Calculation
Uses Date APIs to record borrow and due dates and calculates fine while ensuring borrow and due condition checks.

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🔮 Future Improvements

• User Accounts: Add a User class to associate borrowed items with specific users.
• Persistence: Integrate a database (like SQLite) or file-based storage (like JSON) to save the library's state between sessions.
• Search Functionality: Enhance the Library class with methods to search for items by title or author, not just ID.