How To Device Spacified Layout In Flutter Android App

Widget _portraitView(){
  return Container(
      width: 300.00,
      color: Colors.blueAccent,
      padding: EdgeInsets.fromLTRB(10, 10, 10, 10),
      child: Text(' Portrait View. ',
          textAlign: TextAlign.center,style: TextStyle( color: Colors.white)));
}

Widget _landscapeView(){
  return Container(
      width: 300.00,
      color: Colors.pink,
      padding: EdgeInsets.fromLTRB(10, 10, 10, 10),
      child: Text(' Landscape View.',
          textAlign: TextAlign.center, style: TextStyle( color: Colors.white)));
}

@override
Widget build(BuildContext context) {
  return MaterialApp(
    debugShowCheckedModeBanner: false,
      home: Scaffold(
          appBar: AppBar(
            centerTitle: true,
              backgroundColor: Colors.lightBlueAccent,
              title: Text('Detect Device Screen Orientation')),
          body: OrientationBuilder(
              builder: (context, orientation) {
                return Center(

                    child: orientation == Orientation.portrait
                        ? _portraitView()
                        : _landscapeView()

                );
              }
          )
      )
  );
}

import 'package:flutter/material.dart';

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

class MyApp extends StatelessWidget {

  Widget _portraitView(){
    return Container(
        width: 300.00,
        color: Colors.blueAccent,
        padding: EdgeInsets.fromLTRB(10, 10, 10, 10),
        child: Text(' Portrait View. ',
            textAlign: TextAlign.center,style: TextStyle( color: Colors.white)));
  }

  Widget _landscapeView(){
    return Container(
        width: 300.00,
        color: Colors.pink,
        padding: EdgeInsets.fromLTRB(10, 10, 10, 10),
        child: Text(' Landscape View.',
            textAlign: TextAlign.center, style: TextStyle( color: Colors.white)));
  }

  @override
  Widget build(BuildContext context) {
    return MaterialApp(
      debugShowCheckedModeBanner: false,
        home: Scaffold(
            appBar: AppBar(
              centerTitle: true,
                backgroundColor: Colors.lightBlueAccent,
                title: Text('Detect Device Screen Orientation')),
            body: OrientationBuilder(
                builder: (context, orientation) {
                  return Center(

                      child: orientation == Orientation.portrait
                          ? _portraitView()
                          : _landscapeView()

                  );
                }
            )
        )
    );
  }
}