Localization in flutter and persisting data to local storage

language_repo.dart

class LanguageRepo {
//   contains all the values.
//   for readability when the translations are too much, consider moving all translations to their own files like
//   en_US.dart and assign the en_US in the following line to the referenced value
  static Map<String, String> en_US = {
    "hello": "Hello",
    "good_morning": "Good Morning",
    "i_love_you": "I Love you",
  };
  static Map<String, String> ny_NY = {
    "hello": "Muli bwanji",
    "good_morning": "Mwadzuka bwanji",
    "i_love_you": "Ndimakukonda",
  };
}

locale_controller.dart

import 'package:get/get.dart';
import 'package:language_repo.dart';

class LocaleController extends Translations {
  @override
  Map<String, Map<String, String>> get keys => {
//     to keep the code clean have transferred the values to another file
        "en_US": LanguageRepo.en_US,
        "ny_NY": LanguageRepo.ny_NY,
      };
}

main.dart

import 'package:flutter/material.dart';
import 'package:get/get.dart';
import 'package:locale_controller.dart';
import 'package:shared_preferences/shared_preferences.dart';

void main() async {
  WidgetsFlutterBinding.ensureInitialized();
  SharedPreferences prefs = await SharedPreferences.getInstance();
//   check the language from the shared_prefs
  final isChichewa = prefs.getBool('isChichewa') ?? false;
  runApp(MyApp(isChichewa: isChichewa));
}

class MyApp extends StatelessWidget {
  const MyApp({super.key, required this.isChichewa});
  final bool isChichewa;
  @override
  Widget build(BuildContext context) {
    return GetMaterialApp(
      title: 'Flutter Demo',
      theme: ThemeData(
        primarySwatch: Colors.blue,
      ), 
//       check locale from the sharedPrefs value and display locale based on whats in shredPrefs
      locale: isChichewa ? Locale('ny', 'NY') : Locale('en', 'US'),
      translations: LocaleController(),
       
      home: MyHomePage(),
    );
  }
}

class MyHomePage extends StatelessWidget {
  void _registerChichewa() async {
    // change locale
    var locale = Locale('ny', 'NY');
    Get.updateLocale(locale);
    // save to sharedprefs
    SharedPreferences prefs = await SharedPreferences.getInstance();
    prefs.setBool('isChichewa', true);
  }

  void _registerEng() async {
    // change locale
    var locale = Locale('en', 'US');
    Get.updateLocale(locale);
    // save to sharedprefs
    SharedPreferences prefs = await SharedPreferences.getInstance();
    prefs.setBool('isChichewa', false);
  }

  @override
  Widget build(BuildContext context) {
    return Scaffold(
      body: Center(
        child: Padding(
          padding: const EdgeInsets.all(8.0),
          child: Column(
            mainAxisSize: MainAxisSize.min,
            children: <Widget>[
              Text(
                'hello'.tr,
                style: TextStyle(fontSize: 25),
                textAlign: TextAlign.center,
              ),
              SizedBox(height: 10),
//               use string extension .tr to make the text translatable
              Text(
                'good_morning'.tr,
                style: TextStyle(fontSize: 25),
                textAlign: TextAlign.center,
              ),
              SizedBox(height: 10),
              Text(
                'i_love_you'.tr,
                style: TextStyle(fontSize: 25),
                textAlign: TextAlign.center,
              ),
              MaterialButton(
//                 run the code inside _registerEng function 
                onPressed: _registerEng,
                child: Text('Change to English'),
              ),
              MaterialButton(
                onPressed: _registerChichewa,
                child: Text('Pitani ku Chichewa'),
              ),
            ],
          ),
        ),
      ),
    );
  }
}