Sample to implement the all_translations.dart

all_translations_sample.dart

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

void main() async {
    // Initializes the translation module
    await allTranslations.init();

    // then start the application
    runApp( MyApplication(),);
}

class MyApplication extends StatefulWidget {
    @override
    _MyApplicationState createState() => _MyApplicationState();
}

class _MyApplicationState extends State<MyApplication> {
    @override
    void initState(){
        super.initState();

        // Initializes a callback should something need 
        // to be done when the language is changed
        allTranslations.onLocaleChangedCallback = _onLocaleChanged;
    }

    ///
    /// If there is anything special to do when the user changes the language
    ///
    _onLocaleChanged() async {
        // do anything you need to do if the language changes
        print('Language has been changed to: ${allTranslations.currentLanguage}');
    }

    ///
    /// Main initialization
    ///
    @override
    Widget build(BuildContext context){
        return MaterialApp(
            localizationsDelegates: [
                GlobalMaterialLocalizations.delegate,
                GlobalWidgetsLocalizations.delegate,
            ],
            // Tells the system which are the supported languages
            supportedLocales: allTranslations.supportedLocales(),

            home: HomePage(),
        );
    }
}

class HomePage extends StatefulWidget {
  @override
  _HomePageState createState() => _HomePageState();
}

class _HomePageState extends State<HomePage> {
  @override
  Widget build(BuildContext context) {
    final String language = allTranslations.currentLanguage;
    final String buttonText = language == 'fr' ? '=> English' : '=> Français';

    return Scaffold(
      appBar: AppBar(title: Text(allTranslations.text('main_title'))),
      body: Container(
        width: double.infinity,
        child: Column(
          children: <Widget>[
            RaisedButton(
              child: Text(buttonText),
              onPressed: () async {
                await allTranslations.setNewLanguage(language == 'fr' ? 'en' : 'fr');
                setState((){});
              },
            ),
            Text(allTranslations.text('main_body')),
          ],
        ),
      ),
    );
  }
}