E-commerce System - Java Project

This project is an e-commerce system designed to support basic functionality like adding products to a cart, checking out, and calculating total costs, including shipping. It demonstrates an inventory management system where products may have specific characteristics, such as expiring, being shippable, or requiring special handling.

Features

• Product Management: Define products with attributes like name, price, and quantity, with support for expirable and shippable products.
• Shopping Cart: Add products to a cart with specific quantities, ensuring requested quantities are in stock.
• Checkout: Calculate order subtotal, shipping fees, and total paid amount. Display checkout details in the console.
• Error Handling:
  • Error messages if the cart is empty, the customer's balance is insufficient, a product is out of stock, or expired.
  • Collect all items that require shipping and send them to ShippingService for processing.

Code Overview

Product Hierarchy

1. Product: Base class for all products, holding common attributes (name, price, quantity).
2. ShippableProduct: Extends Product and implements the Shippable interface, adding a weight attribute. For example, TV and Headphones are shippable.
3. ExpirableProduct: Extends ShippableProduct with an expiryDate attribute to represent perishable products. Examples include Cheese and Biscuits.
4. NonShippableProduct: Extends Product, representing items that don’t require shipping, like Mobile Scratch Cards.

CartItem and Cart

• CartItem: Represents a product added to the cart with a specific quantity. It checks stock availability and calculates the total price.
• Cart: Holds a list of CartItem instances, manages subtotal calculation, and validates product stock and expiration status.

Checkout and Shipping

• Checkout: Handles the checkout process by validating the cart, calculating totals, updating customer balance, and reducing product quantities. If items are shippable, it calculates shipping fees based on weight.
• Shipping: Processes all shippable items in the cart, calculating the total weight and displaying shipping information.

Project Structure

Packages, Classes, and Methods

• products Package:
  • Product: Base class with attributes like name, price, and quantity.
  • ShippableProduct: Extends Product, adds weight, and implements the Shippable interface.
  • ExpirableProduct: Extends ShippableProduct, adding an expiryDate and isExpired() method.
  • NonShippableProduct: Extends Product for items that don’t require shipping.
• carts Package:
  • CartItem: Represents a product in the cart with a specified quantity, providing methods to check stock and calculate total price.
  • Cart: Manages a collection of CartItems, providing subtotal calculation, stock validation, and expiration checks.
• services Package:
  • Checkout: Contains the main checkout method, handling order processing and validation.
  • Shipping: Processes all shippable items, calculating shipping costs based on item weight.
• customers Package:
  • Customer: Represents a customer with attributes like name, address, and balance. Provides methods to update balance.

Code Examples

Initializations

// Initialize a customer and a cart
Customer customer = new Customer("Mohamed Eid", "Sadat City", 1500.00);
Cart cart = new Cart();

// Initialize inventory

// Non-expired product
LocalDate cheeseExpiryDate = LocalDate.of(2024, 12, 8);
ExpirableProduct cheese = new ExpirableProduct("Cheese", 30, 9, 0.5, cheeseExpiryDate);

// Expired product
LocalDate orangeExpiryDate = LocalDate.of(2024, 10, 29);
ExpirableProduct orange = new ExpirableProduct("Orange", 25, 12, 0.5, orangeExpiryDate);

// Shippable products
ShippableProduct headPhone = new ShippableProduct("HeadPhone", 350, 5, 0.15);
ShippableProduct tv = new ShippableProduct("TV", 2500, 5, 0.15);

// Non-shippable product
NonShippableProduct scratchCard = new NonShippableProduct("ScratchCard", 100, 20);
 

Adding Products to the Cart and Checking Out

// Add items to cart
cart.add(headPhone, 1);
cart.add(headPhone, 1);
cart.add(cheese, 2);
cart.add(scratchCard, 1);

Checkout.checkout(customer, cart);

Output:

** Shipment notice **
2x HeadPhone    300.0g
2x Cheese       1000.0g
Total package weight is 1.3Kg

** Checkout receipt **
2X HeadPhone    700.0
2X Cheese       60.0
1X ScratchCard  100.0
----------------------
Subtotal        860.0
Shipping        19.5
Amount          879.5 

Example 2: Insufficient balance

// Add items to cart
cart.add(headPhone, 1);
cart.add(headPhone, 1);
cart.add(tv, 1);
cart.add(cheese, 2);
cart.add(scratchCard, 1);

Checkout.checkout(customer, cart);

Output:

Exception in thread "main" java.lang.IllegalArgumentException: 
Customer balance is insufficient.` 

Example 3: Expired product

// Add items to cart
cart.add(headPhone, 1);
cart.add(headPhone, 1);
cart.add(orange, 2);
cart.add(cheese, 2);
cart.add(scratchCard, 1);

Checkout.checkout(customer, cart);

Output:

Exception in thread "main" java.lang.IllegalArgumentException: 
Some ordered items are Expired.

Example 4: Quantity exceeds stock

// Add items to cart
cart.add(headPhone, 1);
cart.add(headPhone, 1);
cart.add(cheese, 20);
cart.add(scratchCard, 1);

Checkout.checkout(customer, cart);` 

Output:

Exception in thread "main" java.lang.IllegalArgumentException: 
Requested quantity is greater than stock.

Example 5: Empty cart checkout

cart.add(headPhone, 1);
cart.add(headPhone, 1);
cart.add(scratchCard, 1);
cart.clearCart();

Checkout.checkout(customer, cart);` 

Output:

Exception in thread "main" java.lang.IllegalArgumentException:
 Cart Is Empty!