Flutter Reorderable List going back to it's original state

I made the list reorderable but now it's going back to its initial state. Can someone help me? My list consists of List Tile which is generated from the database using Asynsnapshot. The key I used is the same as the index. It seems like the insert function isn't inserting the note in the new index. Is it because the future builder is rebuilding?

body: Container(
          padding: EdgeInsets.all(8.0),
          child: ListView(
            children: <Widget>[
              SizedBox(
                  height: MediaQuery.of(context).size.height * 0.882,
                  child: FutureBuilder(
                      future: databaseHelper.getNoteList(),
                      builder: (BuildContext context, AsyncSnapshot snapshot) {
                        if (snapshot.data == null) {
                          return Text('Loading');
                        } else {
                          if (snapshot.data.length < 1) {
                            return Center(
                              child: Text('No Messages, Create New one'),
                            );
                          }
                          return ReorderableListView(
                            children: List.generate(
                              snapshot.data.length,
                              (index) {
                                return ListTile(
                                  key: Key('$index'),
                                  title: Text(
                                    snapshot.data[index].title,
                                    style: TextStyle(
                                      fontWeight: FontWeight.bold,
                                      fontSize: 20,
                                    ),
                                  ),
                                  subtitle: Text(snapshot.data[index].note,
                                      maxLines: 4),
                                  trailing: InkWell(
                                    child: Icon(Icons.add_box,
                                        color: Colors.green),
                                    onTap: () {
                                      TextEditingController txt =
                                          TextEditingController();

                                      txt.text = snapshot.data[index].note;
                                      print(txt);
                                      Route route = MaterialPageRoute(
                                          builder: (context) =>
                                              MyHomePage(custMessage: txt));
                                      Navigator.push(context, route);
                                      // addNewMessageDialog(txt);
                                    },
                                  ),
                                  // isThreeLine: true,
                                  onTap: () {
                                    Route route = MaterialPageRoute(
                                        builder: (context) => AddNote(
                                              note: snapshot.data[index],
                                            ));
                                    Navigator.push(context, route);
                                  },
                                );
                              },
                            ).toList(),
                            onReorder: _onReorder,
                          );
                        }
                      }))
            ],
          )),

Reoder function

void _onReorder(int oldIndex, int newIndex) async {
    var snapshot = await databaseHelper.getNoteList();

    if (newIndex > snapshot.length) newIndex = snapshot.length;
    if (oldIndex < newIndex) newIndex -= 1;
   
      setState(() {
        final Note item = snapshot[oldIndex];
        snapshot.removeAt(oldIndex);

        print(item.title);
        snapshot.insert(newIndex, item);
      });
   
  }

I tried adding future delay but no use.

You can copy paste run full code below
You do not need to call databaseHelper.getNoteList() in _onReorder again
You can use noteList = snapshot.data; and operate noteList

code snippet

void _onReorder(int oldIndex, int newIndex) async {
    if (newIndex > noteList.length) newIndex = noteList.length;
    if (oldIndex < newIndex) newIndex -= 1;

    setState(() {
      final Note item = noteList[oldIndex];
      noteList.removeAt(oldIndex);

      print(item.title);
      noteList.insert(newIndex, item);
    });
  }
...
noteList = snapshot.data;
      return ReorderableListView(

working demo

full code

import 'package:flutter/material.dart';

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

class MyApp extends StatelessWidget {
  @override
  Widget build(BuildContext context) {
    return MaterialApp(
      title: 'Flutter Demo',
      theme: ThemeData(
        primarySwatch: Colors.blue,
        visualDensity: VisualDensity.adaptivePlatformDensity,
      ),
      home: MyHomePage(title: 'Flutter Demo Home Page'),
    );
  }
}

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

  final String title;

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

class Note {
  String title;
  String note;

  Note({this.title, this.note});
}

class databaseHelper {
  static Future<List<Note>> getNoteList() {
    return Future.value([
      Note(title: "1", note: "n1"),
      Note(title: "2", note: "n2"),
      Note(title: "3", note: "n3"),
      Note(title: "4", note: "n4"),
      Note(title: "5", note: "n5")
    ]);
  }
}

class _MyHomePageState extends State<MyHomePage> {
  List<Note> noteList = [];
  Future<List<Note>> _future;

  void _onReorder(int oldIndex, int newIndex) async {
    if (newIndex > noteList.length) newIndex = noteList.length;
    if (oldIndex < newIndex) newIndex -= 1;

    setState(() {
      final Note item = noteList[oldIndex];
      noteList.removeAt(oldIndex);

      print(item.title);
      noteList.insert(newIndex, item);
    });
  }

  @override
  void initState() {
    // TODO: implement initState
    super.initState();
    _future = databaseHelper.getNoteList();
  }

  @override
  Widget build(BuildContext context) {
    return Scaffold(
      appBar: AppBar(
        title: Text(widget.title),
      ),
      body: Container(
          padding: EdgeInsets.all(8.0),
          child: ListView(
            children: <Widget>[
              SizedBox(
                  height: MediaQuery.of(context).size.height * 0.882,
                  child: FutureBuilder(
                      future: _future,
                      builder: (BuildContext context, AsyncSnapshot snapshot) {
                        if (snapshot.data == null) {
                          return Text('Loading');
                        } else {
                          if (snapshot.data.length < 1) {
                            return Center(
                              child: Text('No Messages, Create New one'),
                            );
                          }

                          noteList = snapshot.data;
                          return ReorderableListView(
                            children: List.generate(
                              snapshot.data.length,
                              (index) {
                                return ListTile(
                                  key: Key('$index'),
                                  title: Text(
                                    snapshot.data[index].title,
                                    style: TextStyle(
                                      fontWeight: FontWeight.bold,
                                      fontSize: 20,
                                    ),
                                  ),
                                  subtitle: Text(snapshot.data[index].note,
                                      maxLines: 4),
                                  trailing: InkWell(
                                    child: Icon(Icons.add_box,
                                        color: Colors.green),
                                    onTap: () {
                                      /*TextEditingController txt =
                                      TextEditingController();

                                      txt.text = snapshot.data[index].note;
                                      print(txt);
                                      Route route = MaterialPageRoute(
                                          builder: (context) =>
                                              MyHomePage(custMessage: txt));
                                      Navigator.push(context, route);*/
                                      // addNewMessageDialog(txt);
                                    },
                                  ),
                                  // isThreeLine: true,
                                  onTap: () {
                                    /*Route route = MaterialPageRoute(
                                        builder: (context) => AddNote(
                                          note: snapshot.data[index],
                                        ));
                                    Navigator.push(context, route);*/
                                  },
                                );
                              },
                            ).toList(),
                            onReorder: _onReorder,
                          );
                        }
                      }))
            ],
          )),
    );
  }
}