flutter - StatelessWidget から StatefulWidget にデータを渡す方法

Question

お願いします、データを渡したいです (StatefulWidget の ItemList から FloatingActionButton へのインデックスとリスト)

class _mes_adresseState extends State<mes_adresse> {

  DatabaseHelper databaseHelper = new DatabaseHelper();

  _save(String token) async {
    final prefs = await SharedPreferences.getInstance();
    final key = 'token';
    final value = token;
    prefs.setString(key, value);
  }
  @override
  Widget build(BuildContext context) {
    return MaterialApp(
      home: Scaffold(
        floatingActionButton: FloatingActionButton.extended(
          backgroundColor: Colors.amber,
          onPressed: () {Navigator.of(context).push(
            new MaterialPageRoute(
                builder: (BuildContext context) => new EditAdress(
                      index: i // from index in list view.builder ,
                      list : list // from list in itemlist,
                )),

class ItemList extends StatelessWidget {
  List list;
  ItemList({this.list});

  @override
  Widget build(BuildContext context) {
    return new ListView.builder(
        itemCount: list[0] == null ? 0 : list[0].length,
        itemBuilder: (context, i) {
          return new Container(
            padding: const EdgeInsets.all(1.0),
            child: new GestureDetector(
              onTap: () => Navigator.of(context).push(
                new MaterialPageRoute(
                    builder: (BuildContext context) => new EditAdress(
                      list: list,
                      index: i,
                    )),
                //      builder: (BuildContext context) => new ShowData(list:list , index:i,) ),
              ),

      );},

floatingActionButton は別のページを返し、ページ mes_addresse から liste と index を持っています