search in flutter listview

import 'package:flutter/material.dart';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: 'Flutter Demo',      theme: new ThemeData(        primarySwatch: Colors.blue,      ),      home: new MyHomePage(title: 'ListView with Search),    );  }}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> {  TextEditingController editingController = TextEditingController();  final duplicateItems = List<String>.generate(10000, (i) => "Item $i");  var items = List<String>();  @override  void initState() {    items.addAll(duplicateItems);    super.initState();  }  void filterSearchResults(String query) {    List<String> dummySearchList = List<String>();    dummySearchList.addAll(duplicateItems);    if(query.isNotEmpty) {      List<String> dummyListData = List<String>();      dummySearchList.forEach((item) {        if(item.contains(query)) {          dummyListData.add(item);        }      });      setState(() {        items.clear();        items.addAll(dummyListData);      });      return;    } else {      setState(() {        items.clear();        items.addAll(duplicateItems);      });    }  }  @override  Widget build(BuildContext context) {    return new Scaffold(      appBar: new AppBar(        title: new Text(widget.title),      ),      body: Container(        child: Column(          children: <Widget>[            Padding(              padding: const EdgeInsets.all(8.0),              child: TextField(                onChanged: (value) {                  filterSearchResults(value);                },                controller: editingController,                decoration: InputDecoration(                    labelText: "Search",                    hintText: "Search",                    prefixIcon: Icon(Icons.search),                    border: OutlineInputBorder(                        borderRadius: BorderRadius.all(Radius.circular(25.0)))),              ),            ),            Expanded(              child: ListView.builder(                shrinkWrap: true,                itemCount: items.length,                itemBuilder: (context, index) {                  return ListTile(                    title: Text('${items[index]}'),                  );                },              ),            ),          ],        ),      ),    );  }}