flutter pub add flutter_localizations --sdk=flutter
flutter pub add intl:any

dependencies:
  flutter:
    sdk: flutter
  flutter_localizations:
    sdk: flutter
  intl: any

flutter:
  generate: true

arb-dir: lib/l10n
template-arb-file: app_en.arb
output-localization-file: app_localizations.dart
synthetic-package: true

import 'package:flutter_localizations/flutter_localizations.dart';
import 'package:flutter_gen/gen_l10n/app_localizations.dart'; // Adjust path if synthetic-package is false

// ... inside build method
return MaterialApp(
  localizationsDelegates: const [
    AppLocalizations.delegate,
    GlobalMaterialLocalizations.delegate,
    GlobalWidgetsLocalizations.delegate,
    GlobalCupertinoLocalizations.delegate,
  ],
  supportedLocales: const [
    Locale('en'), // English
    Locale('es'), // Spanish
  ],
  home: const MyHomePage(),
);

{
  "helloWorld": "Hello World!",
  "@helloWorld": {
    "description": "The conventional newborn programmer greeting"
  }
}

{
  "helloWorld": "¡Hola Mundo!"
}

flutter pub get

Text(AppLocalizations.of(context)!.helloWorld)

"hello": "Hello {userName}",
"@hello": {
  "description": "A message with a single parameter",
  "placeholders": {
    "userName": {
      "type": "String",
      "example": "Bob"
    }
  }
}

"nWombats": "{count, plural, =0{no wombats} =1{1 wombat} other{{count} wombats}}",
"@nWombats": {
  "description": "A plural message",
  "placeholders": {
    "count": {
      "type": "num",
      "format": "compact"
    }
  }
}

"pronoun": "{gender, select, male{he} female{she} other{they}}",
"@pronoun": {
  "description": "A gendered message",
  "placeholders": {
    "gender": {
      "type": "String"
    }
  }
}

arb-dir: lib/l10n
template-arb-file: app_en.arb
output-localization-file: app_localizations.dart
synthetic-package: true
use-escaping: true

import 'package:flutter/material.dart';
import 'package:flutter_gen/gen_l10n/app_localizations.dart';

class GreetingWidget extends StatelessWidget {
  final String userName;
  final int notificationCount;

  const GreetingWidget({
    super.key, 
    required this.userName, 
    required this.notificationCount,
  });

  @override
  Widget build(BuildContext context) {
    final l10n = AppLocalizations.of(context)!;

    return Column(
      children: [
        Text(l10n.hello(userName)),
        Text(l10n.nWombats(notificationCount)),
      ],
    );
  }
}