Module 9: Advanced Core Features
Formatting & Localization
Use `String.format`, `Formatter`, and `NumberFormat` for human-friendly output.
Format specifiers (%d, %s, %.2f) provide precise control; use locale-aware factories for currency/percentages.
Adopt MessageFormat or resource bundles for UI strings to avoid concatenation that breaks localization.
Prefer DateTimeFormatter over legacy SimpleDateFormat—immutable and thread-safe.