Posts (238+)

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August 2026

Spring Boot Observability:Health, Metrics, and Correlation IDs

Build an observable Spring Boot service with Actuator health probes, Prometheus metrics, W3C trace context, request IDs, and production-safe endpoint security.

Java

Class-File API:Parse and Transform Bytecode Without ASM

What the Java 24 Class-File API is (JEP 484): parse, generate, and transform .class files with java.lang.classfile so tools track the class-file format without a third-party ASM lag.

Spring Boot

Testing Slices + Testcontainers:Fast Tests Without Booting the Whole App

Choose focused Spring Boot test slices and verify a Spring Data JPA repository against a real PostgreSQL database with Testcontainers.

Java

Markdown Javadoc:Write Docs in `///` Instead of HTML Soup

What Java 23 Markdown documentation comments are (JEP 467): adjacent /// lines, CommonMark plus GFM tables, and how @param and {@link} still work beside /** */.

Spring Boot

Spring Security Basics at the Service

Turn a Spring Boot API into an OAuth2 resource server, validate JWTs locally, and authorize business actions with method security instead of trusting the edge alone.

Java

Foreign Function and Memory API:Call Native Code Without the JNI Stack

What Java 22 FFM is (JEP 454): Arena, MemorySegment, and Linker downcalls so you can call native code and manage off-heap memory without JNI.

Spring Boot

REST API with Boot 3 + Records as DTOs

Design a Spring Boot 3 REST boundary with Java records, Bean Validation, Jackson, and explicit mapping to service-owned models.

Java

Unnamed Variables and Patterns:Ignore What You Do Not Need With `_`

Learn where Java 22 lets you use underscore for intentionally unused locals, catch parameters, lambda parameters, type patterns, and nested record patterns.

Spring Boot

Spring Data JPA Footguns:Entities vs Records, N+1, Transactions

Build a safe Spring Data JPA boundary with proxy-friendly entities, record DTOs, explicit fetch plans, and service-owned transactions.

Java

Stream Gatherers:Custom Intermediate Ops Without Breaking the Pipeline

What Java Stream Gatherers are (JEP 485 / Java 24), why map/filter/flatMap hit a wall, built-ins like windowFixed and fold, and how to write a short custom gatherer.