tablet-app/lib/main.dart

import 'package:flutter/material.dart';

import 'constants.dart';

void main() {
  String initialRoute;

  initialRoute = '/home';

  final MyApp myApp = MyApp(
    initialRoute: initialRoute,
    //context: localContext,
  );

  runApp(myApp);
}

class MyApp extends StatefulWidget {
  final String initialRoute;
  //final Context context;
  MyApp({this.initialRoute});

  // This widget is the root of your application.
  @override
  _MyAppState createState() => _MyAppState();
}

class _MyAppState extends State<MyApp> {
  @override
  Widget build(BuildContext context) {
    return MaterialApp(
      debugShowCheckedModeBanner: false,
      title: 'Tablet App Demo',
      initialRoute: widget.initialRoute,
      supportedLocales: [
        const Locale('en', 'US'),
        const Locale('fr', 'FR'),
      ],
      theme: ThemeData(
        primarySwatch: Colors.grey,
        scaffoldBackgroundColor: kBackgroundColor,
        //fontFamily: "Vollkorn",
        textTheme: TextTheme(bodyText1: TextStyle(color: kBodyTextColor)),
        visualDensity: VisualDensity.adaptivePlatformDensity,
      ),
      routes: {
        '/home': (context) => MyHomePage(title: 'Tablet App Demo Home Page')
      }
    );
  }
}

class MyHomePage extends StatefulWidget {
  MyHomePage({Key key, this.title}) : super(key: key);

  final String title;

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

class _MyHomePageState extends State<MyHomePage> {
  int _counter = 0;

  void _incrementCounter() {
    setState(() {
      _counter++;
    });
  }

  @override
  Widget build(BuildContext context) {
    return Scaffold(
      appBar: AppBar(
        title: Text(widget.title),
      ),
      body: Center(
        child: Column(
          mainAxisAlignment: MainAxisAlignment.center,
          children: <Widget>[
            Text(
              'You have pushed the button this many times:',
            ),
            Text(
              '$_counter',
              style: Theme.of(context).textTheme.headline4,
            ),
          ],
        ),
      ),
      floatingActionButton: FloatingActionButton(
        onPressed: _incrementCounter,
        tooltip: 'Increment',
        child: Icon(Icons.add),
      ),
    );
  }
}