Random Flutter Stream

random_stream.dart

import 'package:flutter/material.dart';
import 'dart:async';
import 'dart:math';

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

class RandomNumberStream {
  final StreamController<int> _nextRandomNumberController = StreamController<int>();
  Stream<int> get stream => _nextRandomNumberController.stream;
  
  RandomNumberStream() {
    Timer.periodic(Duration(seconds: 2), (t) {
      _nextRandomNumberController.sink.add(nextRandomInt());
      
    });
  }
  
  int nextRandomInt() {
    return Random().nextInt(100);
  }
  
  void dispose() {
    _nextRandomNumberController.close();
  }
}


class MyApp extends StatelessWidget {
  @override
  Widget build(BuildContext context) {    
    return MaterialApp(
      theme: ThemeData.dark(),
      debugShowCheckedModeBanner: true,
      home: Scaffold(
        body: Center(
          child: StreamBuilder<int>(
            stream: RandomNumberStream().stream,
            builder: (BuildContext context, AsyncSnapshot<int> snapshot) {
              Widget output;
              final textStyle = TextStyle(fontSize: 24.0);
              
              switch (snapshot.connectionState) {
                case ConnectionState.waiting:
                  output = Text('Waiting...', style: textStyle);
                  break;
                case ConnectionState.none:
                  output = Text('None...', style: textStyle);
                   break;
                case ConnectionState.active:
                  output = Text(snapshot.data.toString(), style: textStyle);
                  break;
                case ConnectionState.done:
                  output = Text('Done...', style: textStyle);
              }
              
              return output;
            }
         ),
        ),
      ),
    );
  }
}