Spring Boot Bean Injection Issue with Package Scanning

Quick Spring Boot tip that saves debugging time: If your @Scheduled method isn't running, check two things: 1. Is @EnableScheduling on your main class? 2. Is the method public and inside a Spring-managed bean? Common mistake: @Component public class JobRunner {   @Scheduled(fixedRate = 5000)   private void runJob() {     // won't run   } } The method is private. Spring can't proxy it. Fix: @Scheduled(fixedRate = 5000) public void runJob() {   // works } Small detail. Easy to miss. Costs 30 minutes of "why isn't this working?" #SpringBoot #Java #BackendDevelopment #Programming

Spent 15 minutes wondering why my @Value annotation wasn't injecting the property. The code: @Component public class AppConfig {   @Value("${app . name}")   private String appName;   public AppConfig() {     System.out.println(appName);   } } It printed null every time. The problem: @Value injection happens after the constructor runs. In the constructor, Spring hasn't injected anything yet. The fix: Use @PostConstruct instead: @PostConstruct public void init() {   System.out.println(appName); } Or use constructor injection: public AppConfig(@Value("${app . name}") String appName) {   this.appName = appName; } Constructor runs first. Injection happens after. Simple timing issue. Easy to miss. #SpringBoot #Java #BackendDevelopment #Programming

Spring Boot profiles are great… until your config starts looking like a multiverse of YAML 😅 In this video, I walk through **Spring Boot Profile Groups** and how they help you bundle profiles without summoning chaos from `application.properties`. Less config spaghetti. More sane environments.   More “it works on my machine” energy — but professionally. 🎥 https://lnkd.in/eBWf6ZJ7 #SpringBoot #Java #BackendDevelopment #SoftwareEngineering #Developers #Programming #Microservices #TechTips

Spent 20 minutes wondering why my Spring Boot app was starting slow. Checked everything. Database connections. External APIs. Nothing obvious. Then I found this: @SpringBootApplication @ComponentScan(basePackages = "com") Scanning "com" means Spring scans every package starting with com. Including third party libraries. The fix: @SpringBootApplication @ComponentScan(basePackages = "com.myapp") Be specific. Only scan your packages. Startup time dropped from 45 seconds to 12 seconds. Small change. Big difference. #SpringBoot #Java #Performance #BackendDevelopment #Programming

🚨 Spring Boot gotcha that cost me hours… I thought my "@Transactional" was working perfectly… Until it silently stopped working 😶 The culprit? 👉 Self Invocation (internal method calls) --- 💥 What works: When a method is called from outside the bean ➡️ Spring Proxy intercepts the call ➡️ Transaction starts ✅ --- ❌ What DOESN’T work: When a method calls another method inside the same class this.placeOrderInternal(); // ❌ bypasses proxy ➡️ No proxy ➡️ No transaction ➡️ No rollback 😬 --- ⚠️ Same problem happens with: - "@Async" - Custom annotations (AOP) - Multi-tenant filters (ThreadLocal based) 👉 Especially when using "@Async" Your logic runs in a different thread ➡️ Filter context is LOST ➡️ Tenant info = NULL 💣 --- 🧠 Why this happens? Spring uses proxies (AOP) No proxy = No magic --- 🛠️ Fixes: ✔️ Call method from another bean ✔️ Inject self proxy ✔️ Use "TransactionTemplate" ✔️ Pass context manually for "@Async" (ThreadLocal won’t work automatically) --- 💡 Real lesson: If Spring can't intercept your call… 👉 Your annotation is just decoration. --- Have you ever debugged something like this for hours? 😅 Drop your experience 👇 #SpringBoot #Java #Backend #Microservices #Programming #100DaysOfCode

🧠 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

💡 Spring Boot Concept Made Simple: @Qualifier vs @Primary While learning Spring Boot, I came across an interesting concept about resolving multiple beans of the same type. To explain it in simple terms, imagine you are at a coffee shop ☕: 🔹 @Qualifier – When you clearly specify which coffee you want. Example: “I want Hazelnut coffee.” Spring injects the **exact bean you specify. 🔹 @Primary– When you just say “Give me a coffee.” Spring automatically provides the default bean marked as `@Primary`. 📌 In short: `@Qualifier` → You choose the specific bean. `@Primary` → Spring chooses the default bean for you. Breaking complex backend concepts into simple real-life analogies makes learning much easier. #SpringBoot #Java #BackendDevelopment #Programming #LearningJourney

🚀 Day 11 of My Spring Boot Learning Journey Today, I started learning about REST APIs in Spring Boot. A REST API (Representational State Transfer) allows different systems to communicate over HTTP using standard methods like GET, POST, PUT, and DELETE. In Spring Boot, we can easily create REST APIs using annotations like @RestController and @RequestMapping. 💡 Basic Flow of REST API: ✔ Client sends request (browser/Postman) ✔ Controller handles the request ✔ Service processes business logic ✔ Response is returned in JSON format REST APIs are widely used in web and mobile applications to connect frontend and backend systems. This is one of the most important concepts for backend developers. #SpringBoot #Java #RESTAPI #BackendDevelopment #Programming #LearningJourney

📘 Spring Notes – 4 Understanding Dependency Injection is one thing… Implementing it is where the real learning happens 💻 Today I worked on: ✔️ Setter vs Constructor Injection ✔️ Autowiring ✔️ Spring Bean Configuration (XML) Also pushed my practice code to GitHub: 👉 https://lnkd.in/gN-j5n3V Slowly building strong backend fundamentals 🚀 Follow for daily updates on my Spring journey. #Java #SpringBoot #Backend #Developers #Learning #TechJourney