Dhushyanth Reddy’s Post

🚨 Why I stopped using field injection in Spring Boot I used to write this: @Autowired private UserService userService; Looks clean… but caused real issues. ❌ Problems: * Hard to test * Hidden dependencies * NullPointer risks in edge cases ✅ Now I always use constructor injection: public UserController(UserService userService) { this.userService = userService; } 💥 Real benefit: While writing unit tests, I realized I could mock dependencies easily without Spring context. 💡 Takeaway: Field injection is convenient. Constructor injection is production-safe. Small change. Big impact. #Java #SpringBoot #BackendDevelopment #SoftwareEngineering  #Microservices #RESTAPI #SystemDesign  #DeveloperLife #100DaysOfCode

Day 31/50 🚀 — Reverse Vowels of a String (LeetCode 345) Today’s problem was a great reminder that sometimes the simplest approaches are the most efficient. 🔹 Used the two-pointer technique 🔹 Focused on in-place swapping 🔹 Optimized for both time (O(n)) and space (O(1)) Key takeaway: Instead of overthinking, break the problem into smaller checks—identify vowels, move pointers smartly, and swap only when needed. Clean and efficient 💡 Happy to see this solution performing well: ⚡ Runtime: 2 ms (faster than 99%+) 📦 Space: Decent optimization #Day31 #LeetCode #DSA #Java #CodingJourney #50DaysOfCode #ProblemSolving #SoftwareEngineering

🧠 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

#Post7 In the previous post, we saw how to handle exceptions globally using @ControllerAdvice. Now let’s take it one step further 👇 How do we handle specific errors properly? That’s where Custom Exceptions come in 🔥 Instead of using generic exceptions, we can create our own exception based on the use case. Example: public class UserNotFoundException extends RuntimeException { public UserNotFoundException(String message) { super(message); } } 👉 Now we can throw this exception when user is not found Example usage: if(user == null){ throw new UserNotFoundException("User not found"); } 💡 Why use Custom Exceptions? • Better error clarity • Easy debugging • More control over API responses Key takeaway: Use custom exceptions to make your API errors more meaningful and structured 👍 In the next post, we will understand validation using @Valid 🔥 #Java #SpringBoot #BackendDevelopment #RESTAPI #LearnInPublic

Got hit with a NullPointerException today. I kept checking the logic again and again… Turns out, I forgot to initialize an object before using it. Fix: Proper initialization before calling methods Lesson learned: Always check for null before using objects. Debugging is frustrating but also the best teacher. #Java #Debugging #DeveloperLife

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

Here’s a quick demo of my Neighborhood Library system built in Java through the Year Up United Application Development program. This video shows the application in action — handling book checkouts, returns, and user interaction through a simple menu-driven interface. Great experience turning concepts into a working program. GitHub: https://lnkd.in/eFMAECUg #YearUpUnited #Java #SoftwareDevelopment #TechJourney

🚀 Day 28/100 – #100DaysOfCode Today’s problem: Reverse Linked List (LeetCode 206) 💡 What I learned: How to reverse a singly linked list using an iterative approach Managing pointers efficiently (prev, curr, next) Understanding how links change direction step by step 🧠 Key Idea: Instead of creating a new list, we reverse the links in-place: Store next node Reverse current pointer Move forward 📊 Complexity: Time: O(n) Space: O(1) Staying consistent, one problem at a time... #Day28 #100DaysOfCode #LeetCode #DSA #LinkedList #Java #CodingJourney #ProblemSolving #TechSkills

Solved: Product of Array Except Self 💡 Key Takeaway: Instead of recalculating product for every index, we can use prefix and suffix products to build the result efficiently. 👉 Approach I followed: - First pass → store left (prefix) product - Second pass → multiply with right (suffix) product - No division used 📊 Time Complexity: O(n) 📦 Space Complexity: O(1) 🔍 What made it interesting: Understanding how left and right contributions combine at each index to avoid redundant calculations. Consistency + clarity is slowly building confidence 💪 #DSA #Java #LeetCode #CodingJourney #BackendDeveloper #SoftwareEngineering