BridgePay E-Commerce Checkout Engine (Java)

A modular Java-based e-commerce checkout system designed using MVC architecture and the Bridge design pattern to support multiple payment methods and payment processors.

This project simulates the core checkout workflow used in real-world e-commerce systems, including cart management, tax calculation, payment processing, and order generation.

Features:

• Product catalog with unique product IDs
• Shopping cart with add, remove, and update quantity functionality
• Automatic subtotal, tax, and total calculation
• Multiple payment methods:
  • Credit Card
  • Debit
  • PayPal
• Multiple payment processors:
  • Stripe (simulated)
  • PayPal (simulated)
  • Mock Bank Processor
• Clean separation of concerns using MVC
• Bridge pattern to decouple payment abstractions from processor implementations
• Console-based UI for interactive checkout
• Order confirmation and receipt generation

Architecture Overview:

This project follows a layered architecture: ecommerce model // Core domain objects (Product, Cart, Order) controller // Business logic and workflow orchestration payment // Payment abstractions (Bridge pattern) processor // Payment processor implementations (Bridge pattern) view // Console-based user interface Main.java // Application entry point

Design Patterns Used

• MVC (Model–View–Controller) for clean separation of responsibilities
• Bridge Pattern to allow payment methods and processors to vary independently

Bridge Pattern Example:

The Bridge pattern allows switching payment processors without modifying payment logic.

java Payment payment = new CreditCardPayment(new StripeProcessor(), "1234"); payment.pay(totalAmount)

The same CreditCardPayment can be processed via Stripe, PayPal,Bank Processor without changing business logic.

How to run: Prerequisites: Java 17+, PowerShell / Terminal Compile and Run (Windows) mkdir bin javac -d bin (Get-ChildItem -Recurse src -Filter *.java | ForEach-Object { $_.FullName }) java -cp bin ecommerce.Main

Sample output:

=== E-Commerce Checkout Engine ===

1. List products
2. Add to cart
3. View cart
4. Update quantity
5. Remove from cart
6. Checkout
7. Exit