named_routes_navigator.dart

import 'package:flutter/material.dart';

void main() => runApp(MyApp());

class MyApp extends StatelessWidget {
  @override
  Widget build(BuildContext context) {
    return MaterialApp(
      title: 'Flutter Demo',
      theme: ThemeData(
        primarySwatch: Colors.blue,
      ),
      initialRoute: HomeScreen.routeName,
      onGenerateRoute: AppRoutes.getRoute,
    );
  }
}

class AppRoutes {
  AppRoutes._();

  static Route getRoute(RouteSettings settings) {
    print('test test ${settings.name}');
    switch (settings.name) {
      case HomeScreen.routeName:
        return _buildRoute(settings, HomeScreen());
      case NormalScreen.routeName:
        return _buildRoute(settings, new NormalScreen());
      case ArgumentsScreen.routeName:
        final argumentValue = settings.arguments;
        return _buildRoute(settings, new ArgumentsScreen(argumentValue));
      default:
        return throw Exception("Route name is incorrect.");
    }
  }

  static MaterialPageRoute _buildRoute(RouteSettings settings, Widget builder) {
    return new MaterialPageRoute(
      settings: settings,
      builder: (BuildContext context) => builder,
    );
  }
}

class HomeScreen extends StatelessWidget {
  static const routeName = '/';

  @override
  Widget build(BuildContext context) {
    return Scaffold(
      body: SafeArea(
        child: Center(
          child: Column(
            mainAxisSize: MainAxisSize.min,
            children: <Widget>[
              RaisedButton(
                onPressed: () {
                  Navigator.pushNamed(
                    context,
                    NormalScreen.routeName,
                  );
                },
                child: Text('Go to Normal screen'),
              ),
              SizedBox(height: 16.0),
              RaisedButton(
                onPressed: () {
                  Navigator.pushNamed(
                    context,
                    ArgumentsScreen.routeName,
                    arguments: 'Hello world',
                  );
                },
                child: Text('Go to Argument screen'),
              ),
            ],
          ),
        ),
      ),
    );
  }
}

class NormalScreen extends StatelessWidget {
  static const routeName = '/normal';

  @override
  Widget build(BuildContext context) {
    return Scaffold(
      body: SafeArea(
        child: Center(
          child: Text('Normal screen'),
        ),
      ),
    );
  }
}

class ArgumentsScreen extends StatelessWidget {
  static const routeName = '/arguments';

  final String value;

  ArgumentsScreen(this.value);

  @override
  Widget build(BuildContext context) {
    return Scaffold(
      body: SafeArea(
        child: Center(
          child: Column(
            mainAxisSize: MainAxisSize.min,
            children: <Widget>[
              Text('Normal screen'),
              SizedBox(height: 16.0),
              Text('Argument value: $value'),
            ],
          ),
        ),
      ),
    );
  }
}