Restaurant Ordering System

A console-based Restaurant Management System implemented in Java demonstrating the use of multiple design patterns including:

Abstract Factory – Different menu types (Vegetarian, Non-Vegetarian, Kids)

Decorator – Dynamic add-ons (Extra Cheese, Barbecue Sauce)

Strategy – Multiple payment methods (Cash, Mobile Wallet, Credit Card)

Observer – Kitchen notification system (Chef & Waiter)

Facade – Simplified interface for placing orders

Strategy (Discount) – Per-item automatic discount logic

Features

Browse 3 different menus: Vegetarian, Non-Vegetarian, and Kids

Add multiple items to a single order

Customize each item with add-ons (stackable)

Automatic per-item discounts:

10% off all Pizzas

8% off Meat items (e.g., Burgers)

6% off Chicken items (e.g., Nuggets)

Choose from 3 payment methods

Real-time kitchen notifications using Observer pattern

Clean bill generation with subtotal, discount, tax (14%), and final total

Design Patterns Used

Pattern Usage

Abstract Factory Creates different menu types

Decorator Adds Extra Cheese / Barbecue Sauce dynamically

Strategy Interchangeable payment & discount strategies

Observer Notifies Chef and Waiter when order starts

Facade Simplifies complex ordering process

Sample Output textWelcome to the Restaurant System!

Choose Menu Type:

Vegetarian Menu

Non-Vegetarian Menu

Kids Menu

Exit Your choice: 1

=== Vegetarian Menu ===

Italian Pizza : 80.00 EGP

Eastern Pizza : 75.00 EGP

Choose item number: 1

Add-ons for this item (choose number):

Extra Cheese (+10)

Barbecue Sauce (+7)

Done Your choice: 1 Added Extra Cheese.

--- Bill ---

Italian Pizza + Extra Cheese : 90.00 EGP Subtotal: 90.00 EGP Discount (per-item): -9.00 EGP Tax (14%): 11.34 EGP Total: 92.34 EGP

Paid 92.34 EGP by Credit Card. Chef received order. Preparing food... Waiter received order. Will serve soon...