test_snackbar

import 'package:flutter/material.dart';

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

class MyApp extends StatelessWidget {
  @override
  Widget build(BuildContext context) {
    return MaterialApp(
      home: Page1(),
    );
  }
}

class Page1 extends StatelessWidget {
  @override
  Widget build(BuildContext context) {
    return Scaffold(
      appBar: AppBar(
        title: Text('Page1'),
      ),
      body: Builder(
        builder: (context) {
          return Center(
              child: Column(
            mainAxisSize: MainAxisSize.min,
            children: <Widget>[
              RaisedButton(
                  onPressed: () {
                    Scaffold.of(context).showSnackBar(SnackBar(content: Text('SnackBar')));
                  },
                  child: Text('1. Click to show SnackBar')),
              RaisedButton(
                  onPressed: () {
                    Navigator.of(context)
                        .push(new MaterialPageRoute(builder: (context) => Page2()));
                  },
                  child: Text('2. Then click to navigate')),
            ],
          ));
        },
      ),
    );
  }
}

class Page2 extends StatelessWidget {
  @override
  Widget build(BuildContext context) {
    return Scaffold(
      appBar: AppBar(
        title: Text('Page2'),
      ),
      body: Center(
        child: Text(
          'after 5 seconds get back to previous page',
          style: TextStyle(
            fontSize: 18,
            fontWeight: FontWeight.bold,
          ),
        ),
      ),
    );
  }
}