- Java Method
A method is a named block of code that takes inputs and optionally produces a result. Methods are how you stop repeating yourself and how you break a large problem into pieces small enough to understand one at a time. Anatomy public — who can call it. Packages covers the four options. int — the…
- React – Rendering Lists and Keys
Rendering an array with map, and the key prop React nags you about. What a key is actually for, why the array index is a bug waiting for the list to reorder, what to use when the items have no id, and why keys must be unique among siblings but not globally.
- Spring Boot – Application Events
Publishing an event instead of calling four services. @EventListener, ordering, async listeners, and @TransactionalEventListener — because a listener that fires before the transaction commits will happily email a customer about an order that is about to be rolled back.
- Angular – Pipes
Formatting values in the template without cluttering the class. `DatePipe`, `CurrencyPipe`, `DecimalPipe` and `AsyncPipe`, chaining pipes and passing arguments, writing a custom pipe, and the pure-versus-impure distinction that decides whether your pipe runs once or on every change detection pass.
- Docker – The Build Context and .dockerignore
`docker build .` uploads that entire directory to the builder before it reads a single instruction — which is why a build can sit for a minute doing apparently nothing. What the context is, why `node_modules` and `target/` must never be in it, and the `.dockerignore` files that took one build from 900 MB of context to 2 MB.