import 'package:flutter/material.dart';

class SnackBarDemo extends StatefulWidget {

  @override

  _SnackBarDemoState createState() => _SnackBarDemoState();

}

class _SnackBarDemoState extends State<SnackBarDemo> {

  @override

  Widget build(BuildContext context) {

    return Scaffold(

      appBar: AppBar(

        title: Text('SnackBarDemo'),

        elevation: 0.0,

      ),

      body: Container(

        padding: EdgeInsets.all(16.0),

        child: Column(

          mainAxisAlignment: MainAxisAlignment.center,

          children: <Widget>[

            Row(

              mainAxisAlignment: MainAxisAlignment.center,

              children: <Widget>[

                SnackBarButton(),

              ]

            ),

          ],

        ),

      ),

    );

  }

}

class SnackBarButton extends StatelessWidget {

  @override

  Widget build(BuildContext context) {

    return FlatButton(

      child: Text('Open SnackBar'),

      onPressed: () {

        Scaffold.of(context).showSnackBar(

          SnackBar(

            content: Text('Processing...'),

            action: SnackBarAction(

              label: 'OK',

              onPressed: () {},

            ),

          )

        );

      },

    );

  }

}