Spring IoC Container | Spring Boot Interview Questions 🔥

Are you preparing for Spring Boot interview questions or brushing up on Spring Core fundamentals? 🚀
This masterclass explains the Spring IoC Container and the complete bean lifecycle step by step using a simple Car Analogy. You’ll learn how beans are created, dependencies injected, lifecycle callbacks executed, and how post-processors like BeanFactoryPostProcessor and BeanPostProcessor work in real-time.

🔑 What You Will Learn

What is the Spring IoC Container?
ApplicationContext vs BeanFactory
How Dependency Injection (DI) works under the hood
Spring Bean Lifecycle explained with @PostConstruct and @PreDestroy
Bean Scopes: Singleton vs Prototype
Role of BeanFactoryPostProcessor (modifies bean definitions before creation)
Role of BeanPostProcessor (modifies beans after creation)
Real-world examples: @Autowired
Key Spring Boot Interview Questions around IoC, DI, and lifecycle

🚗 Car Analogy – Making Spring Easy

Car = Main bean
Battery, Engine, Tyre = Dependencies
IoC Container = Factory that builds & assembles the Car
Dependency Injection = Factory injects battery, engine, tyre before handing over the Car
@PostConstruct = Unlock + start engine
@PreDestroy = Lock + shut down
BeanPostProcessor (Mechanic) = Adds upgrades after the car is built
BeanFactoryPostProcessor (Factory Manager) = Tweaks the recipe before building

🕒 Chapters

00:00 - Spring IoC Container & Lifecycle
00:52 - Standalone Spring Boot Project (Car Analogy)
02:10 - Life Without IoC
04:51 - What is a Spring Container?
06:26 - Defining Beans with @Component
07:05 - Dependency Injection (DI)
08:20 - ApplicationContext
11:15 - Container Lifecycle Start
11:43 - @SpringBootApplication & run()
13:10 - @ComponentScan & @Configuration
14:15 - Annotation-Based Config
15:04 - How a Spring Application Works
15:53 - Spring Bean Lifecycle
17:42 - @PostConstruct Example
20:42 - Closing the Container
21:11 - @PreDestroy Example
24:53 - What is BeanDefinition?
29:17 - Singleton vs Prototype Scope
31:23 - BeanFactoryPostProcessor
34:28 - static @Bean Explained
36:00 - Changing Bean Definitions
39:24 - BeanPostProcessor vs BeanFactoryPostProcessor
40:23 - @PreDestroy & Prototype Conflict
41:32 - Work of BeanPostProcessor
45:08 - postProcessBeforeInitialization
47:22 - Changing a Bean After Creation
52:05 - postProcessAfterInitialization
52:55 - Container Lifecycle End
53:10 - Real-World Uses of BeanPostProcessor

📚 Why Watch This Video?

Covers Spring Core [FOUNDATION] concepts
Explains IoC Container + Bean Lifecycle in detail
Uses real-world Car Analogy to simplify learning
Interview Prep: Most asked Spring Boot interview questions included
Hands-on Spring Boot coding demo


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#springboot #springcore #springframework #springboottutorial

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