My Jev Experiment: Choosing Effort for Codex and Claude Code
A reproducible Jev effort recommendation, the commands to apply it in Codex and Claude Code, and the cache and cost tradeoffs I still need to measure.
October 1, 2026
A software engineering journal
Good code.
Clear thinking.
One refactor at a time.
Notes on Java, architecture, and the tools we use to build better software. Written by Andrés Tascón.
Independent notes. Practical ideas.13 articles · Java / Git / Architecture / AI
01 / The journal
Latest thinking.
Testing Java Backends: Unit, Integration, and Contract Tests
A practical guide to testing strategy for Java backend systems — from unit tests with JUnit and Mockito, to integration tests with Testcontainers, contract tests with Pact, and concurrency tests that catch race conditions. Includes a complete fintech wallet example.
May 22, 2026
Java 25 is here — and it's actually worth upgrading for
Scoped Values are production-ready, object headers just got smaller, and you can finally write code before super(). Here's why Java 25 is the LTS release you shouldn't skip.
May 18, 2026
How to properly build an MCP server
A practical guide to building Model Context Protocol servers — covering tools, resources, and prompts, plus the rules that separate production servers from proof-of-concepts.
May 13, 2026
ACID: Four letters that keep your data safe
A practical guide to Atomicity, Consistency, Isolation, and Durability — with SQL examples and a bank transfer walkthrough showing all four properties in action.
May 4, 2026
HashCode vs Equals in Java: The Contract Every Developer Must Understand
Understand what hashcodes really are, how HashMap lookups work under the hood, and why the hashCode-equals contract is the foundation of every cache and collection in your application.
April 28, 2026
02 / Put it into practice
Reading is the start.
Make it stick.
65 questions to sharpen your understanding of the ideas behind the code.