Get Device Screen Height Width Using Flutter Android App

import 'package:flutter/material.dart';
void main() => runApp(MyApp());
class MyApp extends StatelessWidget {

  @override
  Widget build(BuildContext context) {
    return MaterialApp(
      debugShowCheckedModeBanner: false,
        home: Scaffold(
            body: Center(
                child: GetDimension()
            )
        )
    );
  }
}

class GetDimension extends StatefulWidget {
  GetDimensionState createState() => GetDimensionState();
}

class GetDimensionState extends State {
  double heightHolder = 0.0 ;
  double widthHolder = 0.0 ;
  getHeightWidth(context){
    double width = MediaQuery.of(context).size.width;
    double height = MediaQuery.of(context).size.height;
    setState(() {
      heightHolder = height.roundToDouble();
      widthHolder = width.roundToDouble() ;
    });
  }

  @override
  Widget build(BuildContext context) {
    return Scaffold(
      appBar: AppBar(
        backgroundColor: Colors.amberAccent,
        title: Text('Get Device Height Width'),
      ),
        body: Center(child: Column(
            mainAxisAlignment: MainAxisAlignment.center,
            children: <Widget>[
              Container(
                  padding: EdgeInsets.fromLTRB(0, 20, 0, 10),
                  child: Text('Device Height = '+'$heightHolder',
                      style: TextStyle(fontSize: 21))),

              Container(
                  padding: EdgeInsets.fromLTRB(0, 10, 0, 10),
                  child: Text('Device Width = '+'$widthHolder',
                      style: TextStyle(fontSize: 21))),

              RaisedButton(
                onPressed: () => getHeightWidth(context),
                child: Text('Get Device Height Width Dynamically'),
                textColor: Colors.white,
                color: Colors.amberAccent,
                padding: EdgeInsets.fromLTRB(10, 10, 10, 10),
              )

            ]))
    );
  }
}