main.dart

import 'dart:async';

import 'package:flutter/material.dart';
import 'package:flutter_i18n/flutter_i18n.dart';
import 'package:flutter_i18n/flutter_i18n_delegate.dart';
import 'package:flutter_localizations/flutter_localizations.dart';

Future main() async {
  final FlutterI18nDelegate flutterI18nDelegate = FlutterI18nDelegate(
      useCountryCode: false,
      fallbackFile: 'en',
      path: 'assets/i18n',
      forcedLocale: new Locale('es'));
  WidgetsFlutterBinding.ensureInitialized();
  await flutterI18nDelegate.load(null);
  runApp(new MyApp(flutterI18nDelegate));
}

class MyApp extends StatelessWidget {
  final FlutterI18nDelegate flutterI18nDelegate;

  MyApp(this.flutterI18nDelegate);

  @override
  Widget build(BuildContext context) {
    return new MaterialApp(
      title: 'Flutter Demo',
      theme: new ThemeData(
        primarySwatch: Colors.blue,
      ),
      home: new MyHomePage(),
      localizationsDelegates: [
        flutterI18nDelegate,
        GlobalMaterialLocalizations.delegate,
        GlobalWidgetsLocalizations.delegate
      ],
    );
  }
}

class MyHomePage extends StatefulWidget {
  @override
  MyHomeState createState() => new MyHomeState();
}

class MyHomeState extends State<MyHomePage> {
  Locale currentLang;
  int clicked = 0;

  @override
  void initState() {
    super.initState();
    new Future.delayed(Duration.zero, () async {
      setState(() {
        currentLang = FlutterI18n.currentLocale(context);
      });
    });
  }

  changeLanguage() {
    setState(() {
      currentLang = currentLang.languageCode == 'en'
          ? new Locale('it')
          : new Locale('en');
    });
  }

  incrementCounter() {
    setState(() {
      clicked++;
    });
  }

  @override
  Widget build(BuildContext context) {
    return new Scaffold(
      appBar:
      new AppBar(title: new Text(FlutterI18n.translate(context, "title"))),
      body: new Builder(builder: (BuildContext context) {
        return new Center(
          child: new Column(
            mainAxisAlignment: MainAxisAlignment.center,
            children: <Widget>[
              new Text(FlutterI18n.translate(context, "label.main",
                  Map.fromIterables(["user"], ["Flutter lover"]))),
              new Text(FlutterI18n.plural(context, "clicked.times", clicked)),
              new FlatButton(
                  onPressed: () async {
                    incrementCounter();
                  },
                  child: new Text(
                      FlutterI18n.translate(context, "button.label.clickMe"))),
              new FlatButton(
                  onPressed: () async {
                    changeLanguage();
                    await FlutterI18n.refresh(context, currentLang);
                    Scaffold.of(context).showSnackBar(new SnackBar(
                      content: new Text(FlutterI18n.translate(
                          context, "button.toastMessage")),
                    ));
                  },
                  child: new Text(
                      FlutterI18n.translate(context, "button.label.language")))
            ],
          ),
        );
      }),
    );
  }
}