flutter-localization

Localization Setup

Use Flutter's built-in flutter_localizations and intl packages
Enable generate: true in pubspec.yaml for automatic code generation
Configure l10n.yaml at project root: arb-dir: lib/l10n template-arb-file: app_en.arb output-localization-file: app_localizations.dart output-class: AppLocalizations nullable-getter: false

ARB File Structure

Place all .arb files in lib/l10n/
Use app_{locale}.arb naming convention (e.g., app_en.arb , app_es.arb , app_hi.arb )
The template ARB file (app_en.arb ) MUST contain @ metadata for every key: { "loginTitle": "Sign In", "@loginTitle": { "description": "Title on the login screen" }, "itemCount": "{count, plural, =0{No items} =1{1 item} other{{count} items}}", "@itemCount": { "description": "Item count with pluralization", "placeholders": { "count": { "type": "int" } } } }
Key naming: Use featureName_context format (e.g., settings_title , login_emailHint )
Group keys by feature in the ARB file with comment separators

Usage Rules

Access strings via context.l10n.keyName using a BuildContext extension
STRICTLY prohibit hardcoded user-facing strings anywhere in the codebase
STRICTLY prohibit using .l10n in initState() or outside the widget tree — context must be available
For date/time/number formatting, use intl package formatters with the current locale

Plural & Select Forms

Use ICU plural syntax for countable items: {count, plural, =0{...} =1{...} other{...}}
Use ICU select syntax for gender/category: {gender, select, male{...} female{...} other{...}}
Always include the other case as a fallback

RTL Support

Use Directionality and TextDirection -aware widgets
Prefer EdgeInsetsDirectional over EdgeInsets for padding/margins
Use start /end instead of left /right in MainAxisAlignment and CrossAxisAlignment
Test with RTL locales during widget testing

Adding a New Language

Source Transparency