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Ankur in Hibernate

Spring Data JPA 3 to 4 Migration Guide: Query Derivation Changes, the hibernate-processor Coordinate Swap, and Value-Objects

A beginner-to-advanced guide to migrating the repository layer from Spring Data JPA 3 to 4 on Spring Boot 4.1: the hibernate-jpamodelgen → hibernate-processor coordinate swap and the silent metamodel failure it causes, why derived queries now generate JPQL instead of CriteriaQuery (and the getSingleResultOrNull edge case), records as @Embeddable value objects and projection targets, JSpecify nullability, the refined Specification API, and the removed config that breaks your build — all mapped to real code and errors on a Spring Boot 4.1 app.

Ankur in Java

JSpecify Null-Safety in Spring Boot 4: The Complete Guide (Beginner to Advanced)

Beginner-to-advanced guide to JSpecify null-safety in Spring Framework 7 / Spring Boot 4: the @Nullable/@NonNull migration, Kotlin interop, and a real NullAway build failure caught and fixed on a live Maven project.

Ankur in Java

Undertow to Tomcat 11 Migration Guide: Jakarta EE 11, Servlet 6.1, and What Actually Breaks

A beginner-to-advanced guide to migrating off Undertow on Spring Boot 4: why it was dropped (Jakarta EE 11 / Servlet 6.1), the real Maven error and runtime NoSuchMethodError you get if you fight it, Tomcat 11 tuning, and a verified working Jetty 12.1 alternative — all tested on a real Spring Boot 4.1 app.

Ankur in Java

Spring Framework 7 API Versioning: The Complete Guide (Beginner to Advanced)

A beginner-to-advanced guide to Spring Framework 7's built-in API versioning: the version attribute, baseline versions, the supported-versions gotcha, RFC-compliant deprecation headers, client-side ApiVersionInserter, and testing — verified against a real running Spring Boot 4.1 app.

Ankur in Java

Micrometer to OpenTelemetry: The Spring Boot 4 Observability Guide (Beginner to Advanced)

A beginner-to-advanced guide to Micrometer and Spring Boot 4's new spring-boot-starter-opentelemetry: what actually changed (it isn't "Micrometer 2"), the Observation API, context propagation gotchas, a runnable cardinality-explosion demo, and a full migration checklist.

Ankur in Java

The Foreign Function & Memory API Beyond “Hello, Panama”: Upcalls, errno, and the Coming JNI Lockdown

Beyond the standard strlen/struct tutorials: real, runnable FFM API examples for upcalls (C calling back into Java), capturing errno with Linker.Option.captureCallState, measured downcall overhead, and a practical guide to JEP 472's JNI/FFM lockdown — including live jnativescan output. JDK 22-26.

Ankur in Spring

Surviving the AI Vulnerability Wave: How to Automate Spring Boot Dependency Patches

AI scanners are flooding the Spring ecosystem with patch PRs faster than any team can review. Build an automated remediation pipeline instead: Dependabot or Renovate tuned for Spring Boot parent POMs and BOMs, a Testcontainers regression gate that decides which bumps are safe, and canary deployments for minor framework upgrades.

Ankur in Java

double, BigDecimal, or Fixed-Point: Getting Number Precision Right in Java

Why 0.1 + 0.2 isn't 0.3, when double is fine, when BigDecimal is mandatory, and when fixed-point long is fastest. A beginner-to-advanced guide to number precision in Java — with runnable code, real output, a benchmark, rounding modes, MathContext, and a decision table.

Ankur in Java

Spring Framework 6 to 7 Migration Guide: Breaking Changes, Deprecated APIs, and Upgrade Checklist

A practical Spring Framework 6 to 7 migration guide covering the Jakarta EE 11 baseline, removed and deprecated APIs, AOT and GraalVM changes, BeanRegistrar and proxy lifecycle changes, JSpecify null safety, testing and security implications, an upgrade checklist, and an AI prompt to scan your project.

Ankur in Java

Structured Concurrency in Java: From Your First StructuredTaskScope to Production Patterns (JDK 25/26)

A beginner-to-advanced guide to structured concurrency in Java (JDK 25/26). Learn StructuredTaskScope, Joiners (allSuccessfulOrThrow, anySuccessfulOrThrow, race), timeouts, custom joiners, failure handling, thread-dump observability, and how it compares to CompletableFuture — with runnable code, real output, and a diagram.