A robust console-based e-commerce marketplace application built in Java. It allows users to register, buy and sell products, manage custom persistent shopping carts, and features a secure admin dashboard to monitor sales metrics and top consumers.

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📦 Stack

• Java SE (JDK 8+)
• Plain Text Database File Persistence
• OOP Architecture (Object-Oriented Design)
• Console User Interface

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✨ Quick start

# Clone the repository
git clone https://github.com/manubag/software-design-midterm.git

# Navigate to the directory
cd software-design-midterm

# Compile all Java files into an output folder
javac -d out src/*.java

# Run the compiled application
java -cp out Main

Ensure you run the application from the project root directory so that local text database files (users.txt, Items.txt, and transactions.txt) are created and read correctly.

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⚙️ Features

• Dual Marketplace Roles — Seamless switching between specialized "Buy Menu" and "Sell Menu" roles for active users.
• Inventory Management — Sellers can add new items, replenish stock levels, adjust unit prices, edit product details (name, category, description), and list low-stock items.
• Persistent Shopping Carts — Dedicated user carts saved under cart_<userID>.txt, dynamically loading and saving items across active user sessions.
• Targeted Checkouts — Multi-option checkout support enabling users to purchase their entire cart, items from a specific seller, or individual selected products.
• Secure Admin Panel — Password-protected administrator console (H3LLo?) to view users/sellers, check period sales, seller performance, and top shoppers ("Shopaholics").
• Transactional Ledger — Auto-saving financial statements stored persistently within local flat-file storage files.

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🛠️ How it works

The system follows a clean object-oriented architecture designed in pure Java:

• Modular Structure: Key domain entities (Users, Items, Cart, Transactions) defined as individual classes linked by logical associations and inheritance.
• Custom Serialization: Custom parsing mechanisms designed to serialize and deserialize object properties into plain-text databases using delimiters (| and ;).
• File System Database: Employs pure Java I/O (Scanner, FileWriter, PrintWriter) to orchestrate a fast, lightweight, and fully persistent offline database system.

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📁 Project structure

/
├── src/
│   ├── Cart.java           # Shopping cart entity, item aggregation, and cart file I/O
│   ├── Items.java          # Product details, seller product listings, and stock management
│   ├── Main.java           # Central application menu orchestration and user control flow
│   ├── Transactions.java   # Financial ledger, transactional records, and sales reports
│   └── Users.java          # User profile entity, auth procedures, and serialization logic
├── Items.txt               # Flat-file database containing all listed products
├── transactions.txt        # Local database storing all transactional checkout records
├── users.txt               # Local database storing registered user profiles
└── README.md               # Project documentation

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👤 Authors

• James — github.com/tengkyuuu
• Rhett — github.com/wayne2604