- Java 21 Sequenced Collections
Java 21 added three interfaces — SequencedCollection , SequencedSet and SequencedMap — giving every collection with a defined order the same way to ask for its first and last element, and to iterate backwards. It is a small addition that fixes a twenty-five-year-old inconsistency. The inconsistency…
- Java 21 Record Patterns
A record pattern matches a record and pulls its components out in the same step. It is a small piece of syntax that removes the accessor calls from every branch of a type switch , and it composes to arbitrary depth. It only works on records , and that is not an arbitrary restriction. A record…
- Backend Dev – Get Started
Start here. What a backend engineer builds, the ten things you need to learn and the order to learn them in, and the exact stack every example in this track uses — Java 21 and Spring Boot 4.1. Also: how this track fits with the deeper ones on the site, so you know when to stop reading here and go read those instead.
- Binary Search
Halve the search space every comparison: O(log n), a billion elements in thirty steps. Also the three ways it is habitually got wrong — the midpoint overflow that was in the JDK for nine years, the infinite loop, and the boundary — plus lowerBound, the variant that is actually useful.
- Terraform – Remote State and Locking on S3
Local state works until there are two of you, then it corrupts. The S3 backend, native state locking with `use_lockfile` — and why every tutorial you will find still tells you to create a DynamoDB table that Terraform 1.11 deprecated. Bootstrapping the bucket that holds the state, versioning and encryption on it, and migrating a local state file into it without losing anything.