Refactoring with Copilot: Taming Legacy Java with AI Assist

We often judge Java frameworks by numbers: startup time, memory usage, throughput. But frameworks also shape how we think and experiment. This article walks through six and a half intentionally ridiculous Quarkus demos from JChampions Conference — from Minecraft-based observability to editing source code directly from the Dev UI, to exploring AI hallucinations by breaking every “best practice”. The goal isn’t to copy these ideas into production. The goal is to understand what kind of platform Quarkus really is when you push it beyond the usual paths. If you work with Java and care about developer experience, this one is worth your time. https://lnkd.in/dA28gQSp #Java #Quarkus #SoftwareArchitecture #DeveloperExperience #AIinJava #JVM

🚀 𝗣𝗼𝗹𝘆𝗴𝗹𝗼𝘁 𝗔𝗱𝗮𝗽𝘁𝗲𝗿 → 𝗣𝗼𝗹𝘆𝗴𝗹𝗼𝘁 𝗣𝗹𝗮𝘁𝗳𝗼𝗿𝗺 What started as a runtime abstraction has evolved into a modular polyglot ecosystem. 𝗥𝘂𝗻𝘁𝗶𝗺𝗲: – GraalVM context management – Python / JS inside JVM – Spring Boot integration 𝗧𝗼𝗼𝗹𝗶𝗻𝗴: – Contract-based model – Deterministic Java interface generation – Maven plugin for build-time code generation The goal is simple: Make polyglot integration inside JVM applications structured and production-ready  — 𝘄𝗶𝘁𝗵𝗼𝘂𝘁 𝗶𝗻𝘁𝗿𝗼𝗱𝘂𝗰𝗶𝗻𝗴 𝗮𝗱𝗱𝗶𝘁𝗶𝗼𝗻𝗮𝗹 𝗻𝗲𝘁𝘄𝗼𝗿𝗸 𝗯𝗼𝘂𝗻𝗱𝗮𝗿𝗶𝗲𝘀, 𝗥𝗣𝗖 𝗹𝗮𝘆𝗲𝗿𝘀, 𝗼𝗿 𝗺𝗶𝗰𝗿𝗼𝘀𝗲𝗿𝘃𝗶𝗰𝗲𝘀. The video below shows: 𝗣𝘆𝘁𝗵𝗼𝗻 𝗶𝗺𝗽𝗹𝗲𝗺𝗲𝗻𝘁𝗮𝘁𝗶𝗼𝗻 → 𝗚𝗲𝗻𝗲𝗿𝗮𝘁𝗲𝗱 𝗝𝗮𝘃𝗮 𝗶𝗻𝘁𝗲𝗿𝗳𝗮𝗰𝗲 → 𝗗𝗶𝗿𝗲𝗰𝘁 𝗝𝗩𝗠 𝗲𝘅𝗲𝗰𝘂𝘁𝗶𝗼𝗻. Documentation is being expanded with architecture details and usage examples. Feedback is welcome.

💻 Experimenting with Vibe Coding in a Java Spring Boot Project I recently experimented with vibe coding in one of my Java Spring Boot projects. The code was generated by Copilot using the Claude model. After PR the code through SonarQube Quality Gate, there were quite a few code smells. Main issues detected: • Using hard-coded numeric values instead of constants • Catching exceptions without properly throwing or handling them • Missing early returns where they improve readability • Missing logging in critical paths • Extra or unnecessary attributes generated for Lombok 👨🏫 Lesson to learn: AI can generate working code quickly, but it doesn’t automatically meet production-quality standards like SonarQube. It may be because it doesn't have such standards trained. As developers, we still need to review, refactor, and enforce quality rules. We cannot be lazy and fully depend on code generation. #AI #Copilot #ClaudeAI #Java #SpringBoot #SonarQube #CleanCode #SoftwareEngineering #CodeQuality

🚀 Spring Boot Tip: ModelMapper vs Manual Mapping In many Spring Boot projects, we often need to convert Entity objects into DTOs. There are two ways to do it: ❌ Without ModelMapper • Manual mapping using getters and setters • More boilerplate code • Harder to maintain in large projects ✅ With ModelMapper • Automatic object mapping • Less code and cleaner implementation • Faster development and easier maintenance Using ModelMapper makes the code more readable and scalable when working with DTO patterns in Spring Boot applications. #SpringBoot #Java #BackendDevelopment #ModelMapper #SoftwareDevelopment #JavaDeveloper

OOP is Not Just Theory Most developers say they know OOP. But real understanding means: ✔ Encapsulation → Protecting data with proper access modifiers ✔ Abstraction → Hiding implementation complexity ✔ Inheritance → Code reusability with caution ✔ Polymorphism → Runtime flexibility In backend systems, good OOP design reduces coupling and improves maintainability. #CoreJava #OOP #SoftwareDesign

🚀Understanding @#Autowired in #SpringFramework Today I learned about @Autowired in the Spring Framework. 🔎 @Autowired is used for automatic dependency injection. It tells the Spring Container to automatically inject the required bean. Instead of creating objects manually using new, Spring automatically connects the required dependencies. 📌 Example: @Component public class StudentService { @Autowired private StudentRepository repository; } This helps reduce boilerplate code and makes applications loosely coupled. #SpringFramework #Java #BackendDevelopment #SpringBoot #LearningJourney 10000 Coders Understanding @Autowired Annotation Content: Automatic Dependency Injection Spring injects required beans automatically Reduces manual object creation

Groovy makes JVM development more expressive with powerful operators that reduce boilerplate and prevent common errors. In this tutorial, you’ll learn how to use Groovy operators like: • Elvis Operator • Safe Navigation Operator • Spread Operator • Method Pointer • Direct Field Access Each concept is explained with practical examples so you can write cleaner and safer Groovy code. Perfect for developers working with Groovy, Grails, or JVM-based applications. Read the tutorial: https://lnkd.in/gMehUWrr #groovy #programming #java #softwaredevelopment #backend #coding

📝 Log Error Message in Java try/catch Blocks What Copilot Missed and What SonarQube Enforces? One thing I noticed is the piece of Java code generated by Copilot using Claude didn't meet SonarQube standard because it omitted logging inside catch statements when try/catch was used. Plus exception message is also required to be included in the log. Another thing I noticed is: 🔹 SonarQube in the pipeline enforces this rule strictly 🔹 Local SonarQube (or IDE plugins) does not Here're two use cases we can either log it or do not log it: ✔ Handle the exception → MUST LOG IT try { performAction(); } catch (IOException e) { logger.warn("perform action failed: {}", e.message()); fallback(); } ❌ Do not handle the exception → DO NOT LOG IT (Just rethrow it) try { performAction(); } catch (IOException e) { throw new MyIOException("Unable to perform action", e); // No log here } This prevents double logging. #Java #SpringBoot #SonarQube #CleanCode #SoftwareEngineering #Logging #GitHubCopilot #CodeQuality #BestPractices #DevOps #AI

🚀 𝗪𝗵𝘆 𝗙𝘂𝗻𝗰𝘁𝗶𝗼𝗻𝗮𝗹 𝗜𝗻𝘁𝗲𝗿𝗳𝗮𝗰𝗲𝘀 𝗶𝗻 𝗝𝗮𝘃𝗮 𝗠𝘂𝘀𝘁 𝗛𝗮𝘃𝗲 𝗢𝗻𝗹𝘆 𝗢𝗻𝗲 𝗠𝗲𝘁𝗵𝗼𝗱 In 𝗝𝗮𝘃𝗮 8, functional interfaces were introduced to support 𝗹𝗮𝗺𝗯𝗱𝗮 𝗲𝘅𝗽𝗿𝗲𝘀𝘀𝗶𝗼𝗻𝘀 and enable a more functional programming style. A 𝗳𝘂𝗻𝗰𝘁𝗶𝗼𝗻𝗮𝗹 𝗶𝗻𝘁𝗲𝗿𝗳𝗮𝗰𝗲 is simply an interface that contains 𝗲𝘅𝗮𝗰𝘁𝗹𝘆 𝗼𝗻𝗲 𝗮𝗯𝘀𝘁𝗿𝗮𝗰𝘁 𝗺𝗲𝘁𝗵𝗼𝗱. But why only one? Because 𝗹𝗮𝗺𝗯𝗱𝗮 𝗲𝘅𝗽𝗿𝗲𝘀𝘀𝗶𝗼𝗻𝘀 𝗻𝗲𝗲𝗱 𝗮 𝘀𝗶𝗻𝗴𝗹𝗲 𝘁𝗮𝗿𝗴𝗲𝘁 𝗯𝗲𝗵𝗮𝘃𝗶𝗼𝗿. When the interface has just one abstract method, the compiler knows exactly which method the lambda is implementing. 💡 𝗘𝘅𝗮𝗺𝗽𝗹𝗲: @𝗙𝘂𝗻𝗰𝘁𝗶𝗼𝗻𝗮𝗹𝗜𝗻𝘁𝗲𝗿𝗳𝗮𝗰𝗲 𝗶𝗻𝘁𝗲𝗿𝗳𝗮𝗰𝗲 𝗖𝗮𝗹𝗰𝘂𝗹𝗮𝘁𝗼𝗿 {     𝗶𝗻𝘁 𝗼𝗽𝗲𝗿𝗮𝘁𝗲(𝗶𝗻𝘁 𝗮, 𝗶𝗻𝘁 𝗯); } 𝗖𝗮𝗹𝗰𝘂𝗹𝗮𝘁𝗼𝗿 𝗮𝗱𝗱 = (𝗮, 𝗯) -> 𝗮 + 𝗯; Here, the lambda (𝗮, 𝗯) -> 𝗮 + 𝗯 automatically implements the 𝗼𝗽𝗲𝗿𝗮𝘁𝗲 method. If the interface had multiple abstract methods, the compiler wouldn’t know which method the lambda should represent, making lambdas ambiguous. ⚡ 𝗞𝗲𝘆 𝘁𝗮𝗸𝗲𝗮𝘄𝗮𝘆 Functional interfaces allow 𝗰𝗹𝗲𝗮𝗻𝗲𝗿 𝗮𝗻𝗱 𝗺𝗼𝗿𝗲 𝗰𝗼𝗻𝗰𝗶𝘀𝗲 𝗰𝗼𝗱𝗲, enabling powerful features like: - Lambda expressions - Method references - Stream API All built on the simplicity of 𝗼𝗻𝗲 𝘀𝗶𝗻𝗴𝗹𝗲 𝗮𝗯𝘀𝘁𝗿𝗮𝗰𝘁 𝗺𝗲𝘁𝗵𝗼𝗱. #Java #Java8 #FunctionalProgramming #LambdaExpressions #SoftwareDevelopment

Day 22/100 – Revisiting OOP Concepts in Java ☕💻 Today I went back to the core pillars of Object-Oriented Programming: ✔ Abstraction ✔ Encapsulation ✔ Inheritance ✔ Polymorphism ✔ Association ✔ Aggregation ✔ Composition ✔ Coupling ✔ Cohesion Sometimes we rush into frameworks and advanced topics, but strong fundamentals make everything easier to understand — from backend architecture to scalable system design. Revisiting OOP reminds me that clean structure, low coupling, and high cohesion aren’t just theory… they shape real-world applications. Consistency > Intensity. Still building. 🚀 #100DaysOfCode #Java #OOPS #SoftwareEngineering #CleanCode #Consistency #ComputerScience #LearningJourney