rxdart2

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

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> {
  PublishSubject<String> _textFieldSubject;
  @override
  void initState() {
    _textFieldSubject=PublishSubject<String>();
    _textFieldSubject.listen((data)=>print(data));

    // TODO: implement initState
    super.initState();
  }
  @override
  void dispose() {
    // TODO: implement dispose
    _textFieldSubject.close();
    super.dispose();
  }
  @override
  Widget build(BuildContext context){
    return Scaffold(
      body: Center(
        child: TextField(
          onChanged: (value){
            _textFieldSubject.add('input:$value');
          },
          onSubmitted: (value){
            _textFieldSubject.add('submit:$value');
          },
          decoration: InputDecoration(
            labelText: 'title',
            filled: true,
          ),
        ),
      ),
    );
  }
}