Implementing User-Service with Spring Boot and Java

Day 95/200 – LeetCode Challenge. Problem: Remove Duplicates from Sorted List II (Java) Today’s focus was eliminating all duplicate values from a sorted linked list while keeping only distinct nodes. Implemented an efficient two-pointer approach with a dummy node to handle edge cases cleanly. Linked lists require careful pointer management. Dummy nodes simplify boundary conditions. One-pass solution ensures optimal performance. Continuing the 200-day journey, one problem at a time. #LeetCode #Java #CodingChallenge #200DaysOfCode #ProblemSolving

Spring Boot Filters vs Interceptors — Most developers confuse this 🤯 Let’s simplify 👇 ✅ Filter (Servlet level) - Works BEFORE DispatcherServlet - Used for logging, authentication, request modification ✅ Interceptor (Spring level) - Works AFTER DispatcherServlet - Used for business-level checks 💡 Flow: Request → Filter → DispatcherServlet → Interceptor → Controller ⚡ Real use case: - Filter → JWT validation - Interceptor → role-based access 👉 Choosing wrong = messy architecture Know the difference = cleaner backend 🔥 #SpringBoot #Java #BackendDeveloper

One thing that becomes increasingly important as systems grow is structured logging. In smaller applications, simple logs often work fine. But once multiple services start interacting, finding the root cause of an issue can quickly become difficult. In one system I worked on, introducing consistent log formats and correlation IDs across services made a huge difference. It became much easier to trace requests flowing through different components and identify where failures were happening. Logging sometimes feels like a minor detail during development, but in production it often becomes one of the most valuable tools for debugging distributed systems. Spending a little extra effort on logging early can save a lot of time later when something goes wrong. #SoftwareEngineering #Microservices #BackendDevelopment #Java

Day 74 – Delete Node in a Linked List Solved a unique linked list problem where only the node to be deleted is given, without access to the head. Key Learnings: Learned a technique to delete a node without accessing the previous node Used value replacement and pointer adjustment instead of traditional deletion Strengthened understanding of in-place linked list manipulation #DSA #Java #LinkedList #ProblemSolving #CodingPractice #DataStructures

Spring Boot Circular Proxy Issue — Advanced trap 🤯 Even if you FIX circular dependency… Spring may still create proxies internally. 👉 This can lead to: ❌ Unexpected behavior ❌ Method not executing correctly 💡 Why? Spring uses AOP proxies (JDK / CGLIB) ⚠️ Problem: Internal method calls bypass proxy Example: Method A → calls Method B internally 👉 AOP (like @Transactional) won’t apply 🔥 Solution: ✔ Move logic to another bean ✔ Avoid internal method calls 👉 This is why some transactions “don’t work” Understanding proxies = senior-level Spring knowledge 💯 #SpringBoot #Java #AOP

🚀 #DrGVishwanathanChallenge Day 5 Solved: Rotate Array (Java) 💻 💡 Key Takeaways: Efficient use of array reversal technique In-place operations (O(1) space) Optimizing with O(n) time complexity Consistency + small improvements every day 🔥 📌 #DrGVishwanathanChallenge #VITBhopal #DSA #Java #CodingJourney #Consistency

🚨 Spring Boot Trap @Transactional looks simple. But it has rules. It works when: • Called from another bean • Public methods • Proxy is active It fails silently when: • Self-invocation • Wrong propagation • Async methods Result? Data inconsistency. Always test transaction boundaries. Don’t assume they work. #SpringBoot #Java #Transactions #Backend #BackendDevelopment #JavaDeveloper #SoftwareEngineering #TechTips #SoftwareEngineer

Devlog #14 - PulseNotify Service layer for user-service done. Today: - UserNotFoundException and UserAlreadyExistsException for specific error handling and GlobalExceptionHandler with @ControllerAdvice for structured API responses - UpdateUserRequest DTO as Java Record - UserService with full CRUD + deactivate method Tomorrow I can start with the controller and probably the tests. Step by step the project keeps growing, consistency is key. Link to Github in comments #Java #SpringBoot #Microservices #BuildingInPublic #TechJobs

A small habit that saved me countless debugging hours: Always add meaningful logs. Not just: “Error occurred” But: “Payment service failed while calling order service – orderId:123” Future you (or another developer) will thank you. #Java #CleanCode #SoftwareDevelopment

I've been going through Spring Security in Action - 2nd Edition for some time now. It's been a solid read for getting into the fundamentals of how the framework works under the hood. Application security has become a critical area especially today, where systems are heavily exposed through APIs and AI-driven applications are becoming more common. The book covers key concepts that play a major role in building secure applications. #Java #SpringBoot #SpringSecurity #ApplicationSecurity