primeiro codigo flutter

main.dart

// Copyright (c) 2019, the Dart project authors.  Please see the AUTHORS file
// for details. All rights reserved. Use of this source code is governed by a
// BSD-style license that can be found in the LICENSE file.

import 'package:flutter/material.dart';

    void main(){
        runApp(MaterialApp(
            home: Scaffold(
                appBar: AppBar(
                    title: Text('Primeiro App'),
                ),
                body: Center(
                    child: Text('oi mundo', style: TextStyle(
                      color:Colors.purple,
                      fontSize: 22.3,
                      fontWeight: FontWeight.w700
                    )),
                ),
            )
        ));
    }