问“List<dynamic>”不是类型“Map<dynamic，dynamic>”的子类型

EN

import 'package:firebase_database/firebase_database.dart';
import 'package:flutter/material.dart';

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

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

class _HomeState extends State<Home> {
  final dbRef = FirebaseDatabase.instance.reference().child("qs");

List<Map<dynamic,dynamic>> lists = [];

  @override
  Widget build(BuildContext context) {
    return Scaffold(
        appBar: AppBar(
          title: Text('nothing'),
        ),
        body: FutureBuilder(
            future: dbRef.once(),
            builder: (context, AsyncSnapshot<DataSnapshot> snapshot) {
              if (snapshot.hasData) {
                lists.clear();

Map<dynamic,dynamic> values = snapshot.data.value;
                values.forEach((key, values) {
                  lists.add(values);
                });
                return new ListView.builder(
                    shrinkWrap: true,
                    itemCount: lists.length,
                    itemBuilder: (BuildContext context[enter image description here][1], int index) {
                      return Card(
                        child: Column(
                          crossAxisAlignment: CrossAxisAlignment.start,
                          children: <Widget>[
                            Text("Name: " + lists[index]["name"]),
                            Text("Age: " + lists[index]["age"]),
                            Text("Type: " + lists[index]["type"]),
                          ],
                        ),
                      );
                    });
              }
              return CircularProgressIndicator();
            }));
  }
}