Drawer Widget in Flutter

Syntax:
Drawer({Key key, double elevation: 16.0, Widget child, String semanticLabel}) 

@override
Widget build(BuildContext context) {
  assert(debugCheckHasMaterialLocalizations(context));
  String? label = semanticLabel;
  switch (Theme.of(context).platform) {
    case TargetPlatform.iOS:
    case TargetPlatform.macOS:
      break;
    case TargetPlatform.android:
    case TargetPlatform.fuchsia:
    case TargetPlatform.linux:
    case TargetPlatform.windows:
      label = semanticLabel ?? MaterialLocalizations.of(context).drawerLabel;
  }
  return Semantics(
    scopesRoute: true,
    namesRoute: true,
    explicitChildNodes: true,
    label: label,
    child: ConstrainedBox(
      constraints: const BoxConstraints.expand(width: _kWidth),
      child: Material(
        elevation: elevation,
        child: child,
      ),
    ),
  );
}

import 'package:flutter/material.dart';

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

class MyApp extends StatelessWidget {
static const String _title = 'Drawer Example';

@override
Widget build(BuildContext context) {
	return MaterialApp(
	title: _title,
	home: MyStatefulWidget(),
	);
}
}

class MyStatefulWidget extends StatefulWidget {
MyStatefulWidget({Key key}) : super(key: key);

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

class _MyStatefulWidgetState extends State<MyStatefulWidget> {
int _selectedIndex = 0;
static const TextStyle optionStyle =
TextStyle(fontSize: 30, fontWeight: FontWeight.bold);
static const List<Widget> _widgetOptions = <Widget>[
	Text(
	'Index 0: Home',
	style: optionStyle,
	),
	Text(
	'Index 1: Business',
	style: optionStyle,
	),
	Text(
	'Index 2: School',
	style: optionStyle,
	),
];

void _onItemTapped(int index) {
	setState(() {
	_selectedIndex = index;
	});
}

@override
Widget build(BuildContext context) {
return Scaffold(
	appBar: AppBar(
		title: const Text('BnCodeing'),
		backgroundColor: Colors.green,
	),
	drawer: Drawer(
		child: ListView(
		padding: EdgeInsets.zero,
		children: const <Widget>[
			DrawerHeader(
			decoration: BoxDecoration(
				color: Colors.green,
			),
			child: Text(
				'Drawer Header',
				style: TextStyle(
				color: Colors.white,
				fontSize: 24,
				),
			),
			),
			ListTile(
			leading: Icon(Icons.message),
			title: Text('Messages'),
			),
			ListTile(
			leading: Icon(Icons.account_circle),
			title: Text('Profile'),
			),
			ListTile(
			leading: Icon(Icons.settings),
			title: Text('Settings'),
			),
		],
		),
	),
	);
}
}