Demonstrating the Scaffold's State object

Scaffold_State.dart

import 'package:flutter/foundation.dart';
import 'package:flutter/material.dart';

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

class MyApp extends StatefulWidget {
  MyApp({Key key}) : super(key: key);
  State createState() => _MyAppState();
}

class _MyAppState extends State<MyApp> {
  int _count = 0;
  final GlobalKey keyScaffold = new GlobalKey();
  String hasAppBar = '';
  String hasDrawer = '';
  String hasEndDrawer = '';
  String hasFloatingActionButton = '';
  String appBarMaxHeight = '';
  String isDrawerOpen = '';
  String isEndDrawerOpen = '';

  @override
  Widget build(BuildContext context) {
    final title = 'Floating App Bar';
    final ThemeData theme = Theme.of(context);
    return MaterialApp(
      debugShowCheckedModeBanner: false,
      title: title,
      home: Scaffold(
        key: keyScaffold,
        appBar: AppBar(
          title: Text('Sample Code'),
        ),
        body: Builder(
            builder: (context) => Center(
                    child: Column(
                  mainAxisAlignment: MainAxisAlignment.center,
                  children: <Widget>[
                    Text('You have pressed the button $_count times.'),
                    RaisedButton(
                      onPressed: () {
                        final snackBar = SnackBar(
                            content:
                                Text('Button\'s been pressed $_count times.'));
//                        ScaffoldState state = keyScaffold.currentState;
                        ScaffoldState state = Scaffold.of(context);
                        state.showSnackBar(snackBar);
                        hasAppBar = "Is there an App bar?: ${state.hasAppBar}";
                        hasDrawer = "Is there an Drawer?: ${state.hasDrawer}";
                        hasEndDrawer =
                            "Is there an End drawer?: ${state.hasEndDrawer}";
                        hasFloatingActionButton =
                            "Is there an Floating Action button?: ${state.hasFloatingActionButton}";
                        appBarMaxHeight =
                            "Max height of the app bar is ${state.appBarMaxHeight}";
                        isDrawerOpen =
                            "Is the drawer open?: ${state.isDrawerOpen}";
                        isEndDrawerOpen =
                            "Is the end drawer open?: ${state.isEndDrawerOpen}";
                        setState(() {});
                      },
                      elevation: 20.0,
                      textColor: theme.canvasColor,
                      color: theme.primaryColor,
                      child: Text('Display SnackBar'),
                    ),
                    Text('$hasAppBar'),
                    Text('$hasDrawer'),
                    Text('$hasEndDrawer'),
                    Text('$hasFloatingActionButton'),
                    Text('$appBarMaxHeight'),
                    Text('$isDrawerOpen'),
                    Text('$isEndDrawerOpen'),
                  ],
                ))),
        bottomNavigationBar: BottomAppBar(
          child: Container(
            height: 50.0,
          ),
        ),
        floatingActionButton: FloatingActionButton(
          onPressed: () => setState(() {
                _count++;
              }),
          tooltip: 'Increment Counter',
          child: Icon(Icons.add),
        ),
        floatingActionButtonLocation: FloatingActionButtonLocation.centerDocked,
      ),
    );
  }
}