ATM Machine LLD | Java | State | Chain of Responsibility | SOLID | API Design | Database Schema

🔥 In this video, we design and implement an ATM Machine System in Java from scratch, covering everything from requirements gathering to UML diagrams, database design, api design, and coding. Perfect for LLD interviews! 🚀 What you’ll learn in this video: ----------------------------------------- ✅ How to gather requirements and identify entities for an ATM system ✅ UML Class Diagram for ATM Machine (User, Card, Account, Transaction, ATM, BankService, etc.) ✅ How to apply SOLID principles in an ATM design ✅ Database schema design – relationships between User, Account, Card, and Transaction ✅ API Design thought process for ATM services ✅ Implementing the **State Design Pattern** for ATM states (Idle, CardInserted, PinVerified, OperationSelection, Processing) ✅ Handling invalid operations gracefully in State Pattern ✅ Using **Singleton Pattern** for AtmService (central context) ✅ Using **Chain of Responsibility Pattern** for Cash Dispenser (2000, 500, 200, 100 notes) ✅ Integration of State + COR patterns inside AtmService ✅ Enforcing OOPS principles (Encapsulation, Abstraction, Inheritance, Polymorphism) in our design ✅ Handling ATM cash inventory updates with dispenser chain Good Resource : https://medium.com/@himanshusingour7/how-i-cracked-a-real-lld-interview-367b8a17ea88 https://ujjwalbhardwaj.me/post/low-level-design-design-an-atm-system/ Database Schema Design : https://akhileshmj.medium.com/lld-3-schema-design-df7925322982 💡 This video is perfect for: - Java Developers preparing for **LLD interviews** - Engineers who want to understand **Design Patterns in real-world systems** - Students building **ATM Project in Java** 🔔 Don’t forget to Like, Subscribe, and Share if this video helps you! 🔧 My Tech Gear & Setup 💻 Laptop: Dell Inspiron 15 3000 📱 Phone: https://amzn.to/4qzWrQT 🎧 Headphones: https://amzn.to/4qCwWON ⌨️ Keyboard: https://amzn.to/45lHSIo 🖱️ Mouse: https://amzn.to/45lHSIo 📷 Mic: https://amzn.to/45sGlAj ⌚️ Smartwatch: https://amzn.to/4bfF2IF 🖥️ Monitor: https://amzn.to/4aAZOSR #Java #SystemDesign #LLD #DesignPatterns #ATMProject #StatePattern #ChainOfResponsibility #Singleton #LowLevelDesign #SoftwareEngineering