Inventory Management System

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📖 Overview

This project is a desktop-based Inventory Management System developed using Java Swing.
The system is designed to manage:

• Products
• Stock Levels
• Suppliers
• Orders
• Reports

The application follows a modular and scalable architecture and applies several object-oriented design patterns to ensure maintainability, flexibility, and code reuse.

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🏗️ System Architecture

The system is divided into the following main layers:

1️⃣ UI Layer

Provides graphical user interfaces using Java Swing components.

Main Components:

• MainFrame – Main application window with navigation tabs.
• ProductPanel – Add and list products.
• OrderPanel – Place and view orders.
• SupplierPanel – Manage supplier data.
• ReportPanel – Generate and display reports.

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2️⃣ Model Layer

Represents real-world entities as Java classes:

• Product
• Order
• Supplier
  • LocalSupplier
  • InternationalSupplier

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3️⃣ Manager Layer

Singleton classes responsible for managing system data:

• StockManager
• OrderManager
• SupplierManager

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4️⃣ Factory Layer

Handles object creation logic:

• ProductFactory
• SupplierFactory

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5️⃣ Report Module

Responsible for generating dynamic and formatted reports.

• Uses Decorator Pattern
• Uses Strategy Pattern for report generation

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6️⃣ Observer Module

Handles stock alerts and notifications:

• Notifies when stock levels fall below a defined threshold.

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🧩 Design Patterns Used

1️⃣ Singleton Pattern

Purpose:
Ensures that only one instance of a class exists and provides global access.

Used In:

• StockManager
• OrderManager
• SupplierManager
• ReportGenerator

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2️⃣ Factory Pattern

Purpose:
Creates objects without exposing the creation logic.

Used In:

• ProductFactory
  • Electronics
  • Furniture
  • Groceries
• SupplierFactory
  • Local
  • International

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3️⃣ Adapter Pattern

Purpose:
Allows incompatible interfaces to work together.

Used In:

• ProductAdapter – Adapts product data to report format.
• OrderAdapter – Adapts order data to report format.

Common Interface:

• ReportableAdapter

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4️⃣ Decorator Pattern

Purpose:
Adds responsibilities to objects dynamically.

Used In:

• HeaderDecorator – Adds title and date to reports.
• FooterDecorator – Adds footer/end tag to reports.

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5️⃣ Observer Pattern

Purpose:
Defines a one-to-many dependency between objects.

Used In:

• StockManager notifies observers when stock is low.
• LowStockNotifier implements StockObserver to receive alerts.

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🔍 Component Descriptions

UI Components

• MainFrame: Hosts navigation tabs for all modules.
• ProductPanel: Adds products and displays them in a table.
• OrderPanel: Creates orders and validates inventory levels.
• SupplierPanel: Manages supplier information.
• ReportPanel: Generates inventory and order reports.

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Manager Classes

• StockManager: Manages inventory and observers.
• OrderManager: Stores all orders.
• SupplierManager: Manages suppliers.
• ReportGenerator: Generates formatted reports using adapters.

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Factories

• ProductFactory: Dynamically creates product objects.
• SupplierFactory: Creates supplier instances based on type.

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Report System

Strategies:

• FullInventoryReportStrategy
• LowStockReportStrategy

Decorators:

• HeaderDecorator
• FooterDecorator

Adapters:

• ProductAdapter
• OrderAdapter

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Observer System

• StockObserver interface with onStockLow(Product) method.
• LowStockNotifier prints warnings when stock drops below threshold.

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🛠️ Technologies Used

• Java
• Java Swing
• Object-Oriented Programming (OOP)
• Design Patterns

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✅ Conclusion

This Inventory Management System demonstrates the practical application of multiple design patterns in a real-world Java desktop application, providing a clean, extensible, and maintainable codebase.