Deep dives into Java — concurrency, immutability, hashcodes, dependency injection, and modern language features.
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.
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.
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.
Learn what immutability really means in Java, how to make objects immutable (the five rules), why Strings work the way they do, and every way to make collections immutable — with tradeoffs.
Understand thread safety from first principles — race conditions, shared mutable state, and five practical fixes from `volatile` to database locking. Complete fintech wallet example included.
Learn DI from first principles — constructor vs field injection, interfaces, testability, and why it's a design idea, not a Spring feature.
Learn how to use ExecutorService and Future in Java to build efficient, concurrent applications. This comprehensive guide covers thread pools, task submission, and asynchronous programming patterns.