🌱 Spring Boot Interview Notes — 3 Years Experience

144 Questions · Full Answers · Code Examples · Real-World Production Scenarios

📋 Table of Contents

• Spring Core
• Spring Boot
• Spring MVC
• Spring Data JPA
• Spring Security
• Spring REST APIs
• Spring Boot Testing
• Microservices
• Misc & Real-World Scenarios

🔷 Spring Core

🧠 Mental Model: Think of Spring IoC as a Restaurant Kitchen. You (the code) don’t fetch ingredients yourself. The Kitchen Manager (Spring Container) prepares beans and hands them to you when needed. You just declare what you need — Spring delivers it. “Don’t call us, we’ll call you.”

[ Your Code ]  declares → [ IoC Container ]  injects → [ Dependencies ]
   OrderService            ApplicationContext          PaymentService
                                                       InventoryService

• 1. What is Inversion of Control (IoC)?