Dart Files for the MVCCounterApp. The Counter App using the mvc_pattern plugin.

Controller.dart

import 'package:mvc_pattern/mvc_pattern.dart';

/// Notice 'the rest of the app' has no idea this Dart file even exists.
import 'Model.dart';

class Con extends ControllerMVC {

  factory Con(){
    if(_this == null) _this = Con._();
    return _this;
  }
  static Con _this;

  Con._();

  /// Allow for easy access to 'the Controller' throughout the application.
  static Con get con => _this;

  @override
  initState(){
    /// Demonstrating how the 'initState()' is easily implemented.
    _counter = Model.counter;
  }

  int get displayThis => _counter;
  int _counter;

  void whatever(){
    /// The Controller knows how to 'talk to' the Model. It knows the name, but Model does the work.
    _counter = Model.incrementCounter();
  }
}

Model.dart

class Model{

  static int get counter => _counter;
  static int _counter = 0;

  static int incrementCounter(){
    return ++_counter;
  }
}

MVCCounterApp.dart

import 'package:flutter/material.dart';

/// Notice this Dart file is a little separated from the rest of the app.
/// There is 'no hint' that a MVC design pattern will be utilized in this app.
import 'MyHomePage.dart';

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

class MVCCounterApp extends StatelessWidget {
  // This widget is the root of your application.

  @override
  Widget build(BuildContext context) {
    return MaterialApp(
      title: 'Flutter Demo',
      theme: ThemeData(
        // This is the theme of your application.
        //
        // Try running your application with "flutter run". You'll see the
        // application has a blue toolbar. Then, without quitting the app, try
        // changing the primarySwatch below to Colors.green and then invoke
        // "hot reload" (press "r" in the console where you ran "flutter run",
        // or press Run > Flutter Hot Reload in IntelliJ). Notice that the
        // counter didn't reset back to zero; the application is not restarted.
        primarySwatch: Colors.blue,
      ),
      home: MyHomePage(),
    );
  }
}

MyHomePage.dart

import 'package:flutter/material.dart';

import 'package:mvc_pattern/mvc_pattern.dart';

/// Dependency Injection of 'the Controller' in the design pattern.
import 'Controller.dart';

class MyHomePage extends StatefulWidget {
  MyHomePage({Key key}) : super(key: key);

  // Fields in a Widget subclass are always marked "final".

  static final String title = 'Flutter Demo Home Page';

  @override
  _MyHomePageState createState() => new _MyHomePageState();
}


class _MyHomePageState extends StateMVC {

  _MyHomePageState():super(Controller()){

    _con = Controller.con;
  }
  Controller _con;

  @override
  Widget build(BuildContext context) {
    // This method is rerun every time setState is called.
    //
    // The Flutter framework has been optimized to make rerunning build methods
    // fast, so that you can just rebuild anything that needs updating rather
    // than having to individually change instances of widgets.
    return Scaffold(
      appBar: AppBar(
        // Here we take the value from the MyHomePage object that was created by
        // the App.build method, and use it to set our appbar title.
        title: Text(MyHomePage.title),
      ),
      body: Center(
        // Center is a layout widget. It takes a single child and positions it
        // in the middle of the parent.
        child: Column(
          // Column is also layout widget. It takes a list of children and
          // arranges them vertically. By default, it sizes itself to fit its
          // children horizontally, and tries to be as tall as its parent.
          //
          // Invoke "debug paint" (press "p" in the console where you ran
          // "flutter run", or select "Toggle Debug Paint" from the Flutter tool
          // window in IntelliJ) to see the wireframe for each widget.
          //
          // Column has various properties to control how it sizes itself and
          // how it positions its children. Here we use mainAxisAlignment to
          // center the children vertically; the main axis here is the vertical
          // axis because Columns are vertical (the cross axis would be
          // horizontal).
          mainAxisAlignment: MainAxisAlignment.center,
          children: <Widget>[
            Text(MyHomePage.title,
            ),
            Text(
              '${_con.displayThis}',
              style: Theme.of(context).textTheme.display1,
            ),
          ],
        ),
      ),
      floatingActionButton: FloatingActionButton(
        onPressed: (){
          setState(
              _con.whatever
          );
        },
        tooltip: 'Increment',
        child: Icon(Icons.add),
      ), // This trailing comma makes auto-formatting nicer for build methods.
    );
  }
}