Welcome to the Low Level Designs and Design Patterns repository!
This repository serves as a comprehensive reference for developers mastering Low-Level Design (LLD). It contains production-ready implementations of Object-Oriented Design (OOD) principles, design patterns, and full-scale system design solutions using Java.
Understanding the foundational principles of software architecture.
| Module | Description |
|---|---|
| A_SOLIDPrinciples | Implementation of S.O.L.I.D principles (Single Responsibility, Open/Closed, Liskov Substitution, Interface Segregation, Dependency Inversion). |
Comprehensive implementations of Creational, Structural, and Behavioral patterns.
| Code | Pattern Name | Description |
|---|---|---|
| AA | Singleton | Thread-safe, Lazy, Eager, and Enum implementations. |
| A | Strategy | Interchangeable algorithms (e.g., Parking Spot allocation). |
| B | Observer | Publish-Subscribe mechanism (e.g., Availability notifications). |
| C | Factory | Interface-based object creation logic. |
| D | Abstract Factory | Creating families of related or dependent objects. |
| E | Chain of Responsibility | Passing requests along a chain of handlers. |
| F | Proxy | Controlling access to an object (Lazy loading, Protection). |
| G | Null Object | Handling null references gracefully with default behavior. |
| H | State | Altering object behavior when its internal state changes. |
| I | Composite | Tree structures of objects (Part-Whole hierarchy). |
| J | Adapter | Bridging incompatible interfaces to work together. |
| K | Builder | Step-by-step construction of complex objects. |
| L | Facade | Simplified interface to a complex subsystem. |
| M | Bridge | Decoupling abstraction from its implementation. |
| N | Flyweight | Efficient sharing of objects to reduce memory load. |
Real-world low-level design problems often asked in technical interviews.
| Code | System / Problem | Key Concepts / Description |
|---|---|---|
| C | Parking Lot | Multi-floor parking management, Ticket generation, Spot allocation. |
| CA | Producer Consumer | Multi-threading, Blocking Queues, Concurrency control. |
| D | Tic Tac Toe | Game loop, Board management, Player strategies. |
| E | Car Rental System | Inventory management, Booking reservations, Store locations. |
| F | Snake & Ladder | Game entities (Board, Dice, Player), Movement logic. |
| G | BookMyShow | Movie ticketing, Theater seating, Concurrency handling for booking. |
| H | Vending Machine | State Pattern implementation (Idle, Selection, Dispense). |
| I | ATM Design | State Pattern, Transaction handling, Cash dispensing chain. |
| J | File System | Composite Pattern, Command Pattern for file operations. |
| K | Calculator | Basic arithmetic operations and expression evaluation. |
| -- | Logger | Chain of Responsibility, Log levels, Appenders. |
| M | Uber/Ride Sharing | Driver matching strategies, Trip management, Pricing. |
| N | Zepto/Quick Commerce | Inventory, Order management, Delivery assignment strategies. |
| O | CultFit/Gym | Workout scheduling, Slot booking, Center management. |
| P | Twitter/Social | User graph, News feed generation, Posting, Following. |
| Q | Swiggy/Food Delivery | Restaurant menu, Order processing, Coupons & Discounts. |
| R | Issue Resolver | Ticketing system, Agent assignment, Strategy pattern. |
| S | Text Editor | Flyweight pattern for characters, Formatting, Undo/Redo stack. |
| T | Meeting Scheduler | Calendar slot availability, Invite management (Microsoft Teams style). |
| U | Flight Booking | Airline inventory, Seat selection, Booking status, Search. |
| V | Hotel Management | Room booking, Guest management, Service allocation. |
Follow these steps to get the project up and running on your local machine.
Ensure you have the following installed:
- Java JDK: Version 17+ (Verify with
java -version) - IDE: IntelliJ IDEA (Recommended), Eclipse, or VS Code.
# Clone the repository
git clone [https://github.com/AvinashDogiparthi/LowLevelDesign.git](https://github.com/AvinashDogiparthi/LowLevelDesign.git)
# Navigate to project directory
cd LowLevelDesignContributions are welcome! Whether it's fixing a bug, improving documentation, or adding a new design pattern implementation, your help is appreciated.
- Fork the repository.
- Create a new branch (
git checkout -b feature/AmazingFeature). - Commit your changes (
git commit -m 'Add some AmazingFeature'). - Push to the branch (
git push origin feature/AmazingFeature). - Open a Pull Request.
Please feel free to open Issues for improvements or suggestions.
If you find this repository helpful or use it for your learning, please give it a Star ⭐! Your support encourages the creation of more comprehensive guides and design implementations.
For any queries, feedback, or discussions regarding Low Level Design:
- Email: dnvavinash@gmail.com
- LinkedIN: click here
Feel free to reach out via GitHub for any collaborations!