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(MyApp());

class MyApp extends StatelessWidget {
  @override
  Widget build(BuildContext context) {
    return MaterialApp(
      title: 'Flutter Demo',
      debugShowCheckedModeBanner: false,
      theme: ThemeData(
        primarySwatch: Colors.blue,
      ),
      home: ContadorWidget(),
    );
  }
}

class ContadorWidget extends StatefulWidget {
  @override
  _ContadorWidgetState createState() => _ContadorWidgetState();
}

class _ContadorWidgetState extends State<ContadorWidget> {
    int _contador = 0;

    @override
    Widget build(BuildContext context) {
      return Scaffold(
        appBar: AppBar(
          title: Text("Kung Fu Academy"),
        ),
        floatingActionButton: FloatingActionButton(
          child: Icon(Icons.add),
          onPressed: () {
            print("Este botón ha sido pulsado");
            setState((){
              _contador++;  
            });            
          },
        ),
        body: Center(
          child: Column(
            mainAxisSize: MainAxisSize.max,
            mainAxisAlignment: MainAxisAlignment.center,
            children: <Widget>[
              Text('Nuestra primera aplicacion Flutter'),
              Text(
                _contador.toString(),
                style: Theme.of(context).textTheme.headline4,
              ),
              Text('Hola que tal'),
            ],
          ) 
        )
      );
    }
}