Spring Simplifies with Virtual Threads

🚀 Day 48/180 | #180DaysOfCode 📍 LeetCode | 💻 Java Solved: 1534. Count Good Triplets Used a brute-force triple nested loop to check all possible triplets and validate the given conditions using absolute differences. ⏱️ Time Complexity: O(n³) 📦 Space Complexity: O(1) Strengthening understanding of nested loop patterns and condition-based filtering. 💪 Consistency continues 🚀 #DSA #LeetCode #Java #CodingJourney #Consistency

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 Collection-Based Dependency Injection in Spring When we talk about Dependency Injection (DI) in Spring, most of us think about injecting a single object. But did you know you can inject multiple beans at once using collections? 🤔 Let’s break it down in a simple way 👇 🔹 What is Collection-Based DI? Instead of injecting one object, Spring can inject a list, set, or map of beans into your class. 👉 This is useful when you have multiple implementations of the same interface. 🔹 What’s Happening Here? ✅ Spring scans all beans of type PaymentService ✅ It collects them into a List ✅ Injects them automatically into PaymentProcessor 🔹 Other Supported Collections You can also use: ✔ List<Interface> ✔ Set<Interface> ✔ Map<String, Interface> → Key = bean name Example: Map<String, PaymentService> paymentMap; 🔹 Why is this Useful? ✔ Helps implement strategy pattern easily ✔ Avoids manual bean selection ✔ Makes code more flexible & scalable 🔹 Pro Tip 🚀 Spring injects collections in a specific order if you use @Order or @Priority. 🔚 Summary Collection-based DI = Inject multiple beans → Handle dynamically → Write cleaner code If you're learning Spring deeply, this concept is a game changer when building scalable systems 🔥 #Java #SpringBoot #DependencyInjection #BackendDevelopment #CleanCode

CSBytes #58 - The difference between a tightly coupled application and a loosely coupled, maintainable one is understanding Dependency Injection (DI). When you switch from plain #Java to #SpringBoot, DI changes everything. But how? In my latest article, I explain: The absolute simplest way to think about DI. The practical difference between manual coding and Spring's auto-magic (IoC). Why this matters for clean, testable code. Perfect for anyone needing a simpler way to explain #SoftwareDesign. Link: [https://lnkd.in/gii6p6wY] #Java #SpringBoot #SoftwareDevelopment #CodingTips #TechConcepts

Most beginners get confused with Dependency Injection in Spring Boot. Let me break it down simply Instead of creating objects manually inside a class, Spring Boot automatically provides (injects) the required objects. Without Dependency Injection: You create objects manually → tightly coupled code With Dependency Injection: Spring provides objects → loose coupling & better design In simple terms: Spring Boot = “I’ll give you what you need, you just focus on logic.” This makes applications: • Cleaner • Easier to maintain • More scalable Currently learning and applying these concepts step by step. #SpringBoot #Java #BackendDevelopment #LearningInPublic #FullStackDeveloper

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

JVM Is Not “Compile Once, Run Anywhere” We all learned: Java = Write once, run anywhere. Reality in production: Java = Compile once, optimize everywhere. Your code runs as: .java → .class (bytecode) → JIT → machine code But here’s the catch: - First execution = slow (interpreted) - Hot code = optimized (JIT compiled) Example: for (int i = 0; i < 1_000_000; i++) { process(i); } First few runs: - Slower Later runs: - Much faster (JIT kicks in) 💡 Real-world impact: - First API calls in production may be slower - Warm-up matters in performance testing 💡 Takeaway: Java performance improves over time — not instantly. #Java #JVM #Performance #BackendEngineering

🚀 Day 54/180 | #180DaysOfCode 📍 LeetCode | 💻 Java Solved: 1656. Design an Ordered Stream Used an array + pointer approach to store values by index and return consecutive chunks by moving a pointer forward whenever elements are available. ⏱️ Time Complexity: O(n) (amortized across all insert calls) 📦 Space Complexity: O(n) Strengthening understanding of design problems and pointer-based simulation techniques. 💪 Consistency continues 🚀 #DSA #LeetCode #Java #CodingJourney #Consistency

Java is called platform independent — but here’s what actually happens behind the scenes. When you compile Java code, it doesn’t turn into machine code. It becomes bytecode (.class file), which is not tied to any operating system. This bytecode runs on the JVM (Java Virtual Machine). Each OS has its own JVM, which converts the same bytecode into system-specific instructions. That’s why the same program runs everywhere without rewriting the code. Simple flow: Java Code → Bytecode → JVM → Machine Code It’s not magic — it’s smart design. #Java #JVM #Programming #SoftwareEngineering

"Architecting Knowledge" - Java Wisdom Series Post #13: Sealed Classes - Controlling Your Hierarchy 👇 Open inheritance is technical debt. Here's how to control it. Why This Matters: Sealed classes restrict who can extend your hierarchy, making the set of subtypes finite and known. The compiler can verify exhaustiveness in pattern matching - no default clause needed. When you add a new permitted subclass, every switch breaks until you handle the new case. This turns runtime errors into compile-time errors. Key Takeaway: Use sealed classes when you own the complete set of implementations and want compiler-verified exhaustiveness. Perfect for state machines, result types, and domain models with finite variants. #Java #JavaWisdom #SealedClasses #PatternMatching #ModernJava #TypeSafety Are you still using open inheritance for finite type sets? Time to seal them! All code examples on GitHub - bookmark for quick reference: https://lnkd.in/dJUx3Rd3