- Packages
A package is a namespace. It groups related classes, prevents name collisions between unrelated libraries, and — through access modifiers — decides who can see what. Two classes called Order can coexist happily as long as they live in different packages. Declaring a package The package line must be…
- Static and Final Keywords
Two small keywords that get confused with each other constantly. They are unrelated: static means "belongs to the class, not to an object" , and final means "cannot be reassigned" . Neither implies the other. static fields: one copy, shared Access a static field through the class name —…
- Data Structures & Algorithms – Get Started
Start here. What this track covers and in what order, why it is written in Java 25, and how to run every example yourself with nothing but a JDK — no build tool and no dependencies. Also the one habit that separates people who can answer these questions from people who have only read about them.
- Spring Boot – Building a REST API
@RestController end to end: path and query binding, request bodies, Bean Validation, and returning the right status code instead of 200 for everything. Why the pizza API exposes a UUID rather than its primary key, and why a DTO is not ceremony once an entity has a password field on it.
- Python – Get Started
Start here. Install Python, run your first script, and understand the difference between the REPL and a file. Which Python version this track uses and why, every major 3.x release and what each one added, virtual environments and pip, and the map of the other 25 posts with the order to read them in.