Java on Omar H.Ajmi | Python, Java, Terraform & DevOps TILs

☕ Java records: immutable-ish, like a chocolate shell

Wed, 16 Sep 2026 00:00:00 +0000

☕ Java records: immutable-ish, like a chocolate shell

Java records are lovely. Less boilerplate, clear intent, and no 47-line class just to carry a name and a list.

But there’s a small catch: a record doesn’t automatically make everything inside it immutable.

🧠 The plot twist

public record User(String name, List<String> roles) {}

The record’s component fields are final. But if roles refers to a mutable ArrayList, that list can still change.

🥫 Spring Boot: stop blaming application.yml

Sun, 13 Sep 2026 00:00:00 +0000

🥫 Spring Boot: stop blaming application.yml

The app works locally. In staging, a feature flag is wrong, the port is unexpected, or the service is calling an endpoint nobody remembers configuring.

You open application.yml. It looks perfect.

Time to interrogate the YAML? Not yet. It may have an alibi.

🧵 Java 24: Virtual Threads Finally Stop Getting Stuck on synchronized

Tue, 12 Aug 2025 00:00:00 +0000

🧵 Java 24: Virtual Threads Finally Stop Getting Stuck on synchronized

Virtual threads arrived in Java 21 with a promise: block as much as you like, we’ll make threads cheap. Then came the footnote about synchronized, which sent many people off to rewrite code with ReentrantLock.

🪵 Spring Boot: Structured Logging Without Writing a Single Encoder

Mon, 20 Jan 2025 00:00:00 +0000

🪵 Spring Boot: Structured Logging Without Writing a Single Encoder

Your log aggregator wants JSON. Your application prints a friendly sentence with a timestamp, a thread name and a few dashes.

For years the fix was a hand-rolled Logback encoder, or an extra dependency, or a regex in the log pipeline that everyone was afraid to touch.

☕ Spring Boot: The @Transactional Self-Invocation Trap

Wed, 07 Feb 2024 00:00:00 +0000

☕ Spring Boot: The `@Transactional` Self-Invocation Trap

You added @Transactional. You threw a RuntimeException. You expected the database to roll back.

Yet somehow, your data is still there.

Before blaming your database, check how the method was called. Spring has a little trap called self-invocation, and it can make your transaction annotation look suspiciously decorative.