Counter app implemented with ChangeNotifierProvider

changenotifierprovider_counter.dart

import 'package:flutter/material.dart';
import 'package:provider/provider.dart';

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

class MyApp extends StatelessWidget {
  @override
  Widget build(BuildContext context) {
    return MaterialApp(
      title: 'Flutter Demo',
      home: MyHomePage(),
    );
  }
}

// Counter app with provider

class Counter with ChangeNotifier {
  int count = 0;

  void increment() {
    ++count;
    notifyListeners();
  }
}

class MyHomePage extends StatelessWidget {
  @override
  Widget build(BuildContext context) {
    return ChangeNotifierProvider<Counter>(
      builder: (context) => Counter(),
      child: Scaffold(
        appBar: AppBar(
          title: Text("Page Title"),
        ),
        body: Center(
          child: Column(
            mainAxisAlignment: MainAxisAlignment.center,
            children: [
              Consumer<Counter>(
                builder: (context, counter, child) => Text(
                  '${counter.count}',
                  style: Theme.of(context).textTheme.display1,
                ),
              ),
              Builder(builder: (context) {
                final counter =
                    Provider.of<Counter>(context, listen: false);
                return RaisedButton(
                  onPressed: () => counter.increment(),
                  child: Text("Increment"),
                );
              }),
            ],
          ),
        ),
      ),
    );
  }
}