How To Convert Text To Upper Case & Lower Case In Flutter

import 'package:flutter/material.dart';

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

class MyApp extends StatelessWidget {
  @override
  Widget build(BuildContext context) {
    return MaterialApp(
      debugShowCheckedModeBanner: false,
      home: Scaffold(
          appBar: AppBar(
            centerTitle: true,
            backgroundColor: Colors.lightGreen,
            title: Text("Convert Text To Upper Case Lower Case"),
          ),
          body: SafeArea(
              child : Container(
                alignment: Alignment.center,
                child:MyHomePage(),
              )
          )
      ),
    );
  }
}
class MyHomePage extends StatefulWidget {
  @override
  MyHomePageState createState() => MyHomePageState();
}

class MyHomePageState extends State {

  String output = 'BajarangiSoft.com';

  void convertToLowerCase(){
    setState(() {
      output = output.toLowerCase() ;
    });
  }

  void convertToUpperCase(){
    setState(() {
      output = output.toUpperCase() ;
    });
  }

  Widget build(BuildContext context) {
    return Column(
      children: <Widget>[
        SizedBox(height: 30.0,),
        Container(
            child: Text('$output',
                textAlign: TextAlign.center,
                style: TextStyle(fontSize: 20
                )
            )
        ),
        RaisedButton(
          child: Text('Upper Case'),
          onPressed: convertToUpperCase,
          color: Colors.lightGreen,
          textColor: Colors.white,
        ),
        RaisedButton(
          child: Text('Lower Case'),
          onPressed: convertToLowerCase,
          color: Colors.redAccent,
          textColor: Colors.white,
        ),

      ],
    );
  }
}