The Code Hut

Many developers think their Spring Boot REST APIs are already well-implemented, but subtle mistakes can cause performance issues, security vulnerabilities, and maintenance headaches. In this post, I’ll share 15 common pitfalls and practical tips to build APIs that are fast, secure, and maintainable. 1. 📝 Proper Exception Handling Returning raw exceptions or inconsistent error responses confuses API clients. Use @ControllerAdvice to centralize exception handling. @ControllerAdvice public class GlobalExceptionHandler { @ExceptionHandler(Exception.class) public ResponseEntity<ApiError> handleException(Exception ex) { ApiError apiError = new ApiError(HttpStatus.INTERNAL_SERVER_ERROR, ex.getMessage()); return new ResponseEntity<>(apiError, HttpStatus.INTERNAL_SERVER_ERROR); } } ✅ Ensures clients get clear, consistent error messages and avoids exposing stack traces 2. 🔢 Validate Input Data Skipping input validation leads to err...

Java interviews go beyond syntax. They test core concepts, concurrency, JVM internals, and system design , while also evaluating problem-solving under pressure. Here are 10 common questions and tips to answer them effectively. 🔹 Round 1: Core Java — “Filter the Pretenders” 1. == vs .equals() Testing: object identity vs logical equality. == checks reference equality; .equals() checks logical equivalence. String a = new String("foo"); String b = new String("foo"); System.out.println(a == b); // false System.out.println(a.equals(b)); // true 2. hashCode() vs equals() Testing: Java equality contract. Equal objects must have the same hash code. @Override public boolean equals(Object o) { if (this == o) return true; if (!(o instanceof Person)) return false; Person p = (Person) o; return Objects.equals(id, p.id); } @Override public int hashCode() { return Objects.hash(id); } 3. throw vs throws Testin...

Many developers think their Java code is already fast, but subtle performance issues can accumulate and slow down applications. Here are 18 proven techniques senior developers use to optimize code and make programs faster, cleaner, and easier to maintain. 1. 📝 Efficient String Handling Strings are immutable. Concatenating with + in loops creates many temporary objects. Use StringBuilder or StringJoiner instead. // BAD String result = ""; for(String s : list) { result += s; } // GOOD StringBuilder sb = new StringBuilder(); for(String s : list) { sb.append(s); } String result = sb.toString(); ✅ Use for repeated concatenation; + is fine for one-off cases. 2. 🔢 Use Primitives When Possible // BAD List numbers = new ArrayList (); for(int i = 0; i < 1000; i++) numbers.add(i); // autoboxing // GOOD int[] arr = new int[1000]; for(int i = 0; i < 1000; i++) arr[i] = i; ✅ Primitives avoid extra objects and reduce GC pressure. 3. ♻️ Avoid Unne...

🌐 Distributed Systems Series 📖 Distributed Systems with Java (Series Intro) 📖 Intro to Distributed Systems ☁️ Cloud-Native Considerations ⚠️ Distributed System Anti-Patterns 🧪 Testing Strategies for Distributed Systems 🛡️ Advanced Fault Tolerance 🔗 Distributed Transactions Deep Dive 📈 Microservices Scaling Patterns 🔔 Monitoring & Alerting 📡 Event-Driven Architecture 🔐 Security in Distributed Systems 👀 Observability ⚡ Caching Strategies 📊 Consistency Models 🔍 Service Discovery & Load Balancing 💪 Resilience Patterns 💬 Communication Patterns 🧱 Fault Tolerance & Reliability 🔄 Transactions & Sagas 🤝 Consensus & Coordination 🔒 Concurrency & Locking 🏗️ Microservices & Architecture 🧩 Key Microservices Design Patterns 📐 Applying SOLID Principles 🌐 RESTful API Fundamentals — Designing Clean, Resource-Oriented Endpoints ⚡ REST vs gRPC in Java: Choosing the Right Com...