Spring Bean Lifecycle: Creation to Destruction

Many beginners use Spring annotations like @Autowired and @Component daily, but don’t fully understand what happens behind the scenes. The real magic happens inside the Spring IoC Container. Here’s the step-by-step flow: Spring reads configuration Bean definitions are created IoC container initializes Beans are instantiated Dependencies are injected Lifecycle methods are called Beans become ready to use Destroy methods run when the application stops Without IoC: You manually create objects and manage dependencies. With Spring IoC: Spring creates, manages, and injects everything for you. Example: Engine engine = new Engine(); Car car = new Car(engine); vs Car car = context.getBean(Car.class); That’s why Spring applications stay cleaner, more scalable, and easier to maintain. Key concepts: BeanFactory ApplicationContext Dependency Injection Bean Lifecycle Autowiring Bean Scope If you are learning Spring Boot, understanding IoC is one of the most important fundamentals. #SpringBoot #Java #BackendDevelopment #SoftwareEngineering #Programming #Developers #Coding #JavaDeveloper #DependencyInjection #SpringFramework

Most developers get this wrong. Do you? 🛑 Early in my Java journey, I thought inheritance was a feature to use freely. The more you extended, the more reusable the code, right? Wrong. Uncontrolled inheritance creates hierarchies nobody can reason about. And Java had no clean answer for it — until sealed classes. ━━━━━━━━━━━━━━━━━━━━━━━━━ Sealed Classes, introduced in Java 17, let you define exactly which classes are permitted to extend yours. No surprises. No rogue subclasses. Just clean, intentional design. public sealed class Shape   permits Circle, Rectangle, Triangle {} Each permitted subclass must be one of: → final — no further extension → sealed — further restricted with its own permits → non-sealed — open again by choice And the bonus? Exhaustive pattern matching with switch. The compiler knows every possible subtype. You get compile-time safety for free. ━━━━━━━━━━━━━━━━━━━━━━━━━ I’ve written a full breakdown — how sealed classes work, the rules, and real use cases. Read it here 👇 https://lnkd.in/gsN6Dp7j Have you used sealed classes in your projects? I’d love to hear how! #Java #Java17 #Coding #SoftwareDevelopment #TechCommunity #LearningInPublic #SealedClasses #BackendDevelopment #SoftwareEngineering #CleanCode #OOP

🚀 Understanding Autowire byName in Spring In Spring Framework, Autowire byName is a type of automatic dependency injection where the container matches a bean with a property based on its name. 👉 In simple words: Spring looks for a bean whose id/name matches the variable name in your class. 🔹 How it works? ✔ Spring checks the property name ✔ Finds a bean with the same name ✔ Injects it automatically 🔹 Example: class Student { private Address address; public void setAddress(Address address) { this.address = address; } } <bean id="address" class="com.example.Address"/> <bean id="student" class="com.example.Student" autowire="byName"/> 👉 Here, the property name address matches the bean id address, so Spring injects it automatically. 🔹 Key Points ✔ Works only with setter methods ✔ Depends on matching names exactly ✔ Easy to use but less flexible than annotations 💡 Pro Tip: In modern Spring Boot, we mostly use @Autowired instead of XML-based autowiring. ✨ Understanding these basics helps you master Spring Dependency Injection! Anand Kumar Buddarapu #Java #SpringBoot #DependencyInjection #Autowiring #BackendDevelopment #SoftwareEngineering #LearningJourney

🧠 After learning Dependency Injection, I had one big question 👀 Who actually creates these objects in Spring Boot, and when? Today I explored the Spring Bean Lifecycle 🚀 Simple flow 👇 1️⃣ Spring container starts 2️⃣ Bean object is created 3️⃣ Dependencies are injected 4️⃣ Bean becomes ready to use 5️⃣ Bean is destroyed when the app shuts down What made this even more interesting 👇 ✅ @PostConstruct → runs after bean creation ✅ @PreDestroy → runs before bean cleanup 💡 My takeaway: Spring doesn’t just inject dependencies — it also manages the entire lifecycle of the object. The more I learn this framework, the more beautifully engineered it feels ⚡ #Java #SpringBoot #BeanLifecycle #BackendDevelopment #LearningInPublic

🔗 Understanding @Autowired in Spring Boot While building my Spring Boot project, I explored how different components are connected without manually creating objects. 🔹 What is @Autowired? It is used for Dependency Injection, which allows Spring to automatically provide the required objects instead of creating them manually using "new". 💡 Why is it useful? It helps in writing cleaner and loosely coupled code, making applications easier to manage and scale. For example, instead of creating a service object inside a controller, Spring injects it automatically using @Autowired. Understanding this concept gave me a better idea of how Spring manages objects internally 💻 #SpringBoot #Java #DependencyInjection #BackendDevelopment #TechLearning

The @Component annotation is Spring’s primary stereotype for marking a Java class as a managed bean. During classpath scanning, Spring automatically detects these annotated classes and registers them in the ApplicationContext to enable Dependency Injection. This allows the framework to handle the entire object lifecycle and fulfill dependencies through Inversion of Control. It also serves as the foundation for specialized annotations like @Service and @Repository, which provide additional architectural context and layer-specific behavior. Session is live on my YT channel. Please attend the complete session and share with fellow developers. Here is the session link - https://lnkd.in/gNKzts3k #SpringBoot #Java #SpringFramework #BackendDevelopment #thinkconstructive #TechLearning #JavaDeveloper #SoftwareEngineering #SoftwareDeveloper

𝗟𝗲𝘁'𝘀 𝗱𝗶𝘀𝗰𝘂𝘀𝘀 𝗝𝗘𝗣𝟱𝟮𝟲. 𝗙𝗿𝗼𝗺 𝗦𝘁𝗮𝗯𝗹𝗲𝗩𝗮𝗹𝘂𝗲 𝘁𝗼 𝗟𝗮𝘇𝘆𝗖𝗼𝗻𝘀𝘁𝗮𝗻𝘁: 𝗮 𝗰𝗵𝗮𝗻𝗴𝗲, 𝗮 𝗯𝗶𝗴 𝗶𝗺𝗽𝗿𝗼𝘃𝗲𝗺𝗲𝗻𝘁 𝗶𝗻 𝘂𝗻𝗱𝗲𝗿𝘀𝘁𝗮𝗻𝗱𝗶𝗻𝗴 I really like the new name LazyConstant in JEP 526. LazyConstant is a name that actually shows how we use LazyConstant. That is important. 𝗠𝘆 𝗼𝗯𝘀𝗲𝗿𝘃𝗮𝘁𝗶𝗼𝗻 𝗳𝗿𝗼𝗺 𝗲𝘅𝗽𝗲𝗿𝗶𝗺𝗲𝗻𝘁𝗶𝗻𝗴 𝘄𝗶𝘁𝗵 𝗶𝘁 Before when we made a constant field in a class it was always initialized when the class was loaded. This means that: ● Even if we never use the value ● Even if you're just running a quick test ● If initializing the constant is expensive Our class loading time still takes a hit. I tried this out with a demo using: java -verbose:class DemoApp And I can see how initialization affects the time it takes to load the class. 𝗪𝗵𝗮𝘁 𝗶𝘀 𝗱𝗶𝗳𝗳𝗲𝗿𝗲𝗻𝘁 𝘄𝗶𝘁𝗵 𝗟𝗮𝘇𝘆𝗖𝗼𝗻𝘀𝘁𝗮𝗻𝘁? Now the constant LazyConstant: ● Only loads when we actually need it ● Does not slow down the class loading ● Still keeps the guarantee that it will not change The result is that our program starts up more smoothly and quickly. This is especially important for: ● Microservices (where the time it takes to start up matters a lot) ● Applications with a lot of configuration ● Logging or creating objects 𝗪𝗵𝘆 𝘁𝗵𝗶𝘀 𝗶𝘀 𝗮 𝗯𝗶𝗴 𝗱𝗲𝗮𝗹 𝗶𝗻 𝗿𝗲𝗮𝗹 𝗹𝗶𝗳𝗲: Before LazyConstant we could do lazy initialization but: ● It required a lot of code ● We had to be careful with concurrency ● Often used double-checked locking + synchronized ● It was easy to get it wrong 𝘄𝗶𝘁𝗵 𝗟𝗮𝘇𝘆𝗖𝗼𝗻𝘀𝘁𝗮𝗻𝘁? ● We do not need any extra code patterns ● We do not have to worry about concurrency ● Our code is clean and easy to read 𝗪𝗵𝗲𝗿𝗲 𝗜 𝘁𝗵𝗶𝗻𝗸 𝗟𝗮𝘇𝘆𝗖𝗼𝗻𝘀𝘁𝗮𝗻𝘁 𝘄𝗶𝗹𝗹 𝗵𝗮𝘃𝗲 𝘁𝗵𝗲 𝗶𝗺𝗽𝗮𝗰𝘁: ● The part of the JVM that loads classes ● Linking phase performance ● The overall time it takes to start up It is still a preview feature in JDK 26. Lazyconstant feels like one of those features that will quietly improve a lot of real-world systems. JEP 526: https://lnkd.in/gSVBkfQy #java #programming #engineering #jep #jvm

How Ioc Container of Spring Boot Works? Today, I deepened my understanding of how the IoC (Inversion of Control) container works in Spring Boot. The IoC container is the core of Spring’s dependency management system—it takes over the responsibility of creating, managing, and injecting objects (beans) in an application. Instead of manually instantiating objects, the container automatically wires dependencies, which allows developers to write cleaner and more maintainable code. Beans can be defined using annotations like @Component, @Service, @Repository, or via @Configuration and @Bean, and the container ensures their proper initialization and lifecycle management. What fascinated me is how Spring Boot handles everything behind the scenes: it scans packages for components, registers them as bean definitions, resolves dependencies, and manages scopes such as singleton, prototype, or request-scoped beans. It also provides hooks for bean post-processing and lifecycle events like @PostConstruct and @PreDestroy. This system not only reduces boilerplate code but also enables features like testing with mocks, AOP (aspect-oriented programming), and flexible configuration, making the development of complex applications much more manageable. Learning the internal workings of the IoC container gave me a much clearer picture of how Spring Boot promotes decoupled, modular, and maintainable design, which is essential for building scalable Java applications. #SpringBoot #Java #OOP #DependencyInjection

💡 Types of Dependency Injection in Spring – Setter vs Constructor Injection Dependency Injection is a core concept in the Spring Framework that helps in building loosely coupled and maintainable applications. Among the different types, Setter Injection and Constructor Injection are the most commonly used. Setter Injection is performed using setter methods. In this approach, the container injects dependencies after the object is created. It provides flexibility because dependencies can be modified at runtime if needed. However, it may allow incomplete object creation if required dependencies are not set. On the other hand, Constructor Injection is performed through the constructor of a class. All required dependencies are provided at the time of object creation, ensuring that the object is fully initialized. This makes the application more robust and promotes immutability, as dependencies cannot be changed later. In simple terms: 🔹 Setter Injection → Flexible → Can change values later 🔹 Constructor Injection → Mandatory dependencies → More secure & reliable In real-world applications, Constructor Injection is generally preferred for mandatory dependencies, while Setter Injection is useful for optional configurations. Understanding these approaches helps in designing clean architecture and writing better Spring applications 🚀 Thank you sir Anand Kumar Buddarapu #Java #Spring #DependencyInjection #BackendDevelopment #Programming #TechLearning #SoftwareDevelopment

Why Spring Is Moving Back Toward Simplicity Reactive programming became popular because: - Threads were expensive - Blocking didn’t scale That led to code like this: Mono<User> user = service.getUser()   .flatMap(this::validate)   .flatMap(this::enrich); Powerful — but hard to: - Read - Debug - Maintain Virtual threads allow this again: User user = service.getUser(); validate(user); enrich(user); Same scalability. Much clearer flow. 💡 Takeaway: Spring and Java are converging toward readability. #Java #SpringBoot #BackendEngineering #Java25