import 'package:flutter/material.dart';


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

  @override
  State<StatefulWidget> createState() {
    // TODO: implement createState
    return new DetailCommentHeaderState();
  }
}

class DetailCommentHeaderState extends State<DetailCommentListHeader> with AutomaticKeepAliveClientMixin<DetailCommentListHeader> {
  @override
  // TODO: implement wantKeepAlive
  bool get wantKeepAlive => true;

  @override
  void initState() {
    // TODO: implement initState
    super.initState();
    print('DetailCommentHeaderState initState');
  }

  @override
  void dispose() {
    // TODO: implement dispose
    super.dispose();
    print("DetailCommentListHeader dispose");
  }

  @override
  Widget build(BuildContext context) {
    super.build(context);
    String text = 'need keep alive';

    // TODO: implement build
    return new Container(
      color: Colors.white,
      height: 48.0,
      child: new Padding(padding: new EdgeInsets.fromLTRB(16.0, 14.0, 0.0 , 14.0,),
        child: new Text(text, style: new TextStyle(fontSize: 16.0, fontWeight: FontWeight.bold),),
      ),
    );
  }
}

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

class MyApp extends StatelessWidget {
  // This widget is the root of your application.
  @override
  Widget build(BuildContext context) {
    return new MaterialApp(
      title: 'Keep Alive Demo',
      theme: new ThemeData(
        primarySwatch: Colors.blue,
      ),
      home: new MyHomePage(title: 'Flutter Demo Home Page'),
    );
  }
}

class MyHomePage extends StatefulWidget {
  MyHomePage({Key key, this.title}) : super(key: key);
  final String title;

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

class _MyHomePageState extends State<MyHomePage> {
  @override
  Widget build(BuildContext context) {
    return new Scaffold(
      appBar: new AppBar(
        title: new Text(widget.title),
      ),
      body: new ListView.builder(
          itemCount: 50,
          itemBuilder: (BuildContext context, int index){
            if (index == 0){
              return new DetailCommentListHeader();
            }
            return new Container(
              height: 44.0,
              child: new Text('just padding'),
              color: Colors.yellow.shade300,
            );
          },
      ), // This trailing comma makes auto-formatting nicer for build methods.
    );
  }
}