Stream02

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

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

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

class HomePage extends StatefulWidget {
  @override
  _HomePageState createState() => _HomePageState();
}

class _HomePageState extends State<HomePage> {
  StreamController<String> _streamController;
  StreamSubscription _streamSubscription;
  StreamSink _streamSink;
  @override
  void dispose() {
    // TODO: implement dispose
    _streamController.close();
    super.dispose();
  }
  @override
  void initState() {
    // TODO: implement initState
    _streamController=StreamController<String>.broadcast();
    _streamSink=_streamController.sink;
    _streamSubscription=_streamController.stream.listen(onData,onError: onError, onDone: onDone);
    super.initState();
  }
  void addDataToStream()async{
    print('begin to add data to stream');
    String data=await(fetchData());
    _streamSink.add(data);
    print('Endding of data to stream');
  }

  pauseStream(){
    _streamSubscription.pause();
  }
  cancelStrem(){
    _streamSubscription.cancel();
  }
  resumeStream(){
    _streamSubscription.resume();
  }

  onData(value){print('$value');}
  onError(Error){print('$Error');}
  onDone(){print('done');}

  Future<String> fetchData()async{
    int _index=0;
    List<String> _listStream=['anounce','Bond','Country','Document','Effect','feel','Glove','Hover','Indent','Jack','Kick','Log','Moon','New','Opertiunity','Post','Queen'];
    await Future.delayed(Duration(seconds:1));
    _index=Random().nextInt(16);
    return _listStream[_index];
  }

  @override
  Widget build(BuildContext context) {
    return Scaffold(
      appBar: AppBar(title: Text('Hello World'),),
      body: Center(
        child: Column(
          children: <Widget>[
            StreamBuilder(
              stream: _streamController.stream,
              initialData: '...',
              builder:(BuildContext context,snapshot){
                return Text('${snapshot.data}');
              },
            ),
            RaisedButton(
              child: Icon(Icons.add),
              onPressed:addDataToStream,
            ),
            RaisedButton(
              child: Text('Cancel'),
              onPressed:cancelStrem,
            ),
            RaisedButton(
              child: Text('Pause'),
              onPressed:pauseStream,
            ),
            RaisedButton(
              child: Text('Resume'),
              onPressed:resumeStream,
            ),
          ],
        ),
      ),
    );
  }
}