Build and test an LLM gateway on Spring AI 2.0: hint-based routing, failover that works with the new tool-calling advisor, one circuit breaker per provider, token and dollar caps, and a semantic cache. Every number comes from a run.
A Spring AI 2.0 RAG pipeline on Spring Boot 4.1, taken apart one stage at a time on a real PostgreSQL with pgvector: chunking, once-only PDF ingestion, the similarity threshold that is off by default, injection-proof tenant filters, reranking and answer checks. Every number comes from a committed transcript, and the page says plainly what was scripted.
Records, pattern-matching switch, virtual threads, sequenced collections, scoped values and structured concurrency from Java 21 to Java 25 LTS, each compiled and run on JDK 21, 25, 26 and 27: what is really final, when virtual threads stopped pinning, and what 26 and 27 mean for the road to Java 29.
A hands-on comparison of Java virtual threads (Project Loom) against platform threads — with a 28× I/O benchmark, CPU-bound proof, memory comparison table, HttpClient real-world example, architecture diagram, and a decision table for when NOT to use virtual threads.
A step-by-step Java 21 to 25 upgrade guide: Maven and Gradle files, Lombok and Mockito versions, removed and warned APIs, a 12-item checklist and seven AI prompts. Every claim was run on JDK 21, 25, 26 and 27, and the old guide's mistakes are corrected.
A practical cookbook for the Java Stream API and Collectors utility — filter/map/reduce essentials, groupingBy and partitioningBy patterns, performance gotchas, and AI prompts to refactor legacy loops into clean pipelines.
A practical walkthrough of Java's three classic concurrency tools — ExecutorService, CompletableFuture, and ForkJoinPool — with runnable examples, guidance on when to use each, and AI prompts for refactoring legacy concurrent code.
A practical guide to the modern Java test stack — JUnit 6 as the runner, AssertJ for fluent assertions, Mockito 5 for mocking, and Testcontainers for real infrastructure. Includes runnable examples for each and AI prompts to generate and refactor tests.
A copy-paste playbook of AI prompts for migrating Java codebases between every LTS jump: 8→11, 11→17, 17→21, and 21→25. Use them in Claude, ChatGPT, Gemini, or Cursor to automate the repetitive parts of a version upgrade.
Adding two integers looks trivial until the sum overflows silently. This guide covers five quick ways to add, then goes deep: the wraparound reproduced with real numbers, Math.addExact and the exact-arithmetic family, widening to long, BigInteger, and the bit trick addExact itself uses.