- 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.
- React Native – TextInput and Forms
`TextInput` is where a mobile app is won or lost. `keyboardType` and `textContentType` change the keyboard itself and unlock password autofill; `autoCapitalize="none"` on an email field is the single most common React Native bug. Controlled inputs, validation without a form library, per-field errors, and submitting from the keyboard when there is no Enter key.