Simple Inventory Management System

A beginner-friendly Java application demonstrating Factory and Strategy design patterns through a command-line inventory system.

Features

• Add products (Books, Electronics) using Factory Pattern
• Calculate discounts (Student, Bulk, None) using Strategy Pattern
• Process sales and track inventory
• View inventory statistics and reports

Quick Start

Prerequisites

• Java 17+
• Maven 3.6+

Run the Application

# Method 1: Direct execution
mvn compile
java -cp target/classes inventory.Main

# Method 2: JAR file
mvn package
java -jar target/simple-inventory-1.0.0.jar

# Method 3: Docker
mvn package
docker build -t simple-inventory .
docker run -it simple-inventory

Project Structure

src/main/java/inventory/
├── Product.java              # Data model
├── ProductFactory.java       # Factory Pattern
├── DiscountCalculator.java   # Strategy Pattern  
├── InventoryManager.java     # Business logic
└── Main.java                 # CLI interface

src/test/java/inventory/
├── ProductFactoryTest.java
├── DiscountCalculatorTest.java
└── InventoryManagerTest.java

Design Patterns

Factory Pattern

// Creates products without exposing creation logic
Product book = ProductFactory.createProduct("Book", "Java Guide", 29.99, 10);
Product laptop = ProductFactory.createProduct("Electronics", "Laptop", 799.99, 5);

Strategy Pattern

// Different discount algorithms
double studentDiscount = DiscountCalculator.calculateDiscount(book, 2, "Student");  // 10% off books
double bulkDiscount = DiscountCalculator.calculateDiscount(laptop, 6, "Bulk");      // 15% off 5+ items

Testing

# Run all tests
mvn test

# Run specific test
mvn test -Dtest=ProductFactoryTest

Usage

1. Run the application
2. Use menu options:
   • Add Product → Demonstrates Factory Pattern
   • Sell Product → Demonstrates Strategy Pattern
   • View Inventory → See current stock
   • View Statistics → Inventory reports

Learning Objectives

• Implement Factory and Strategy design patterns
• Write unit tests with JUnit 5
• Use Maven for build management
• Deploy with Docker containers
• Follow clean code practices

Troubleshooting

# If compilation fails
mvn clean compile -U

# If Docker build fails
mvn clean package
ls target/simple-inventory-1.0.0.jar  # Verify JAR exists
docker build -t simple-inventory .