stream.dart

import 'dart:async';
import 'dart:collection';
import 'package:flutter/foundation.dart';
import 'package:flutter/material.dart';
import 'package:provider/provider.dart';

void main() {
  runApp(MyApp());
}

class Person {
  int age = 0;
  Person({this.age}) {
    print("person hashcode: ${this.hashCode}");
  }
}

class PersonStreamController {
  StreamController<Person> _controller = StreamController<Person>();

  Stream<Person> getStream() {
    return _controller.stream;
  }

  void updateStream(Person person) {
    _controller.add(person);
  }
}

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

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

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

class _MyHomePageState extends State<MyHomePage> {
  String text = "hello";
  var person = Person();

  var personStreamController = PersonStreamController();

  @override
  Widget build(BuildContext context) {
    return StreamProvider<Person>.value(
      value: personStreamController.getStream(),
      initialData: Person(age: 0),
      child: Scaffold(
        floatingActionButton: Consumer<Person>(
          builder: (context, person, child) {
            return FloatingActionButton(
              child: Icon(Icons.add),
              onPressed: () {
                personStreamController.updateStream(Person(age: person.age + 1));
              },
            );
          },
        ),
        appBar: AppBar(
          title: Text("Future Provider"),
        ),
        body: Consumer<Person>(
          builder: (context, value, child) {
            return Center(child: Text("Person's age: ${value.age}"));
          },
        ),
      ),
    );
  }
}