Multi language Flutter

 

Multi language Flutter

 

import 'dart:io';
import 'package:flutter/material.dart';
import 'package:flutter_localizations/flutter_localizations.dart';

void main() async {
  WidgetsFlutterBinding.ensureInitialized();

  // Get the initial locale values
  final String defaultSystemLocale = Platform.localeName;
  final List<Locale> systemLocales = WidgetsBinding.instance.window.locales;

  // Define locales that our app supports (no country codes, see comments below)
  final appSupportedLocales = <Locale>[
    Locale('ru'),
    Locale('en'),
  ];

  final MyApp myApp = MyApp(defaultSystemLocale, systemLocales);

  runApp(
      MaterialApp(
        title: 'MyApp',
        home: myApp,
        supportedLocales: appSupportedLocales,
        localizationsDelegates: [
          // These are default localization delegates that implement the very basic translations for standard controls and date/time formats.
          GlobalMaterialLocalizations.delegate,
          GlobalWidgetsLocalizations.delegate,
        ],
      )
  );
}

class MyApp extends StatefulWidget {
  // Store initial locale settings here, they are unchanged
  final String initialDefaultSystemLocale;
  final List<Locale> initialSystemLocales;

  MyApp(this.initialDefaultSystemLocale, this.initialSystemLocales);

  @override
  _MyAppState createState() => _MyAppState();
}


class _MyAppState extends State<MyApp> with WidgetsBindingObserver {
  // Store dynamic changeable locale settings here, they change with the system changes
  String currentDefaultSystemLocale;
  List<Locale> currentSystemLocales;

  // Here we read the current locale values
  void setCurrentValues() {
    currentSystemLocales = WidgetsBinding.instance.window.locales;
    currentDefaultSystemLocale = Platform.localeName;
  }

  @override
  void initState() {
    // This is run when the widget is first time initialized
    WidgetsBinding.instance.addObserver(this); // Subscribe to changes
    setCurrentValues();
    super.initState();
  }

  @override
  void didChangeLocales(List<Locale> locale) {
    // This is run when system locales are changed
    super.didChangeLocales(locale);
    // Update state with the new values and redraw controls
    setState(() {
      setCurrentValues();
    });
  }

  @override
  Widget build(BuildContext context) {
    return Scaffold(
      appBar: AppBar(),
      body: Column(
        crossAxisAlignment: CrossAxisAlignment.start,
        mainAxisAlignment: MainAxisAlignment.start,
        children: <Widget>[
          Text('Initial system default locale: ${widget.initialDefaultSystemLocale}.'),
          Text('Initial language code: ${widget.initialDefaultSystemLocale.split('_')[0]}, country code: ${widget.initialDefaultSystemLocale.split('_')[1]}.'),
          Text('Initial system locales:'),
          for (var locale in widget.initialSystemLocales) Text(locale.toString()),
          Text(''),
          Text('Current system default locale: ${currentDefaultSystemLocale}.'),
          Text('Current system locales:'),
          for (var locale in currentSystemLocales) Text(locale.toString()),
          Text(''),
          Text('Selected application locale: ${Localizations.localeOf(context).toString()}.'),
          Text(''),
          Text('Current date: ${Localizations.of<MaterialLocalizations>(context, MaterialLocalizations).formatFullDate(DateTime.now())}.'),
          Text('Current time zone: ${DateTime.now().timeZoneName} (offset ${DateTime.now().timeZoneOffset}).'),
        ],
      ),
    );
  }
}

 

Custom Lang class:

1. BaseLanguage.dart

import 'dart:io';



import 'lang_en.dart';

import 'lang_vi.dart';



abstract class BaseLanguage {

  String hello;

}

/// Usage:

/// BaseLanguage lang;

/// @override

//   void initState() {

//     lang = LangUtils.getLang();

//     String testTitle = lang.hello;

//   }

class LangUtils {

  static BaseLanguage getLang() {

    String defaultLocale = Platform.localeName; //ex: en_US

    print('defaultLocale = $defaultLocale');



    switch (defaultLocale) {

      case 'en_US':

        return LangEn();

      default:

        return LangVi();

    }

  }

}

 

2. LangEn.dart

import 'BaseLanguage.dart';



// en_US

class LangEn implements BaseLanguage {

  @override

  String hello = 'hello';

}

 

3. LangVi.dart

import 'BaseLanguage.dart';



// vi_VN

class LangVi implements BaseLanguage {

  @override

  String hello = 'Xin chào';

}