ListView.builder itemCount未更新

我有一个小部件，它返回ListView.builder，当用户到达ListView的底部时，ListView的项作为小部件的参数传递，并加载新项。但是当项目被加载时，itemCount不会更新，如果打印value参数，我会得到正确数量的项目，但是我会得到一个索引错误，前面的值作为范围。。。 这是我的日志：

I/flutter ( 4654): 4
I/flutter ( 4654): 8

════════ Exception caught by widgets library ═══════════════════════════════════════════════════════
The following RangeError was thrown building:
RangeError (index): Invalid value: Not in range 0..3, inclusive: 4

When the exception was thrown, this was the stack: 
#0      List.[] (dart:core-patch/growable_array.dart:146:60)
#1      _UsersListViewState.showFollowButton (package:the_spot/services/library/usersListView.dart:167:30)
#2      _UsersListViewState.showResultWidget (package:the_spot/services/library/usersListView.dart:147:43)
#3      _UsersListViewState.build.<anonymous closure> (package:the_spot/services/library/usersListView.dart:75:20)
#4      SliverChildBuilderDelegate.build (package:flutter/src/widgets/sliver.dart:446:22)
...
════════════════════════════════════════════════════════════════════════════════════════════════════

I/颤振（4654）：4
I/颤振（4654）：8
════════ widgets库捕获到异常═══════════════════════════════════════════════════════
在生成时引发了以下RangeError：
RangeError（索引）：无效值：不在范围0..3中，包括：4
引发异常时，这是堆栈：
#0列表。[]（dart:core patch/Growtable_阵列。dart:146:60）
#1 _UsersListViewState.showFollowButton（包：the_spot/services/library/usersListView.dart:167:30）
#2 _UsersListViewState.showResultWidget（包：the _spot/services/library/usersListView.dart:147:43）
#3_UsersListViewState.build。（软件包：the_spot/services/library/usersListView.dart:75:20）
#4 SliverChildBuilderDelegate.build（包：flatter/src/widgets/sliver.dart:446:22）
...
════════════════════════════════════════════════════════════════════════════════════════════════════

查看第一次加载项目时，它会打印项目计数（4），并且没有发生错误（在我的屏幕上，我也有项目列表），但是当用户向下滚动以更新项目列表时，它会打印新的项目计数（8），但范围仍然是4

这里是小部件代码（我删除了不必要的内容）：

导入“包装：颤振/材料.省道”；
导入“package:the_spot/pages/home_page/profile.dart”；
导入“package:the_spot/services/library/userProfile.dart”；
导入“包：_spot/services/library/configuration.dart”；
导入“../theme.dart”；
导入“../database.dart”；
导入“library.dart”；
类UsersListView扩展StatefulWidget{
最终配置；
最终列表查询；
BottomListReachedCallback的最终作废回调；
constUsersListView（{Key-Key，this.configuration，this.query，this.onbottomListReacheCallback}）：super（Key:Key）；
@凌驾
_UsersListViewState createState（）=>\u UsersListViewState（）；
}
类_UsersListViewState扩展状态{
列表waitForFollowing=[]；
列出FriendRequestalReadyOne=[]；
列表waitForSendingFriendRequest=[]；
bool isLoadingData=false；
@凌驾
void initState（）{
super.initState（）；
waitForFollowing.clear（）；
widget.query.forEach（（元素）{
waitForFollowing.add（false）；
waitForSendingFriendRequest.add（false）；
if（element.pendingFriendsId
.indexOf（widget.configuration.userData.userId）=
-1) {
friendRequestAlreadyDone.add（true）；
}否则{
friendRequestAlreadyDone.add（false）；
}
});
}
@凌驾
void didUpdateWidget（UsersListView oldWidget）{
super.didUpdateWidget（oldWidget）；
isLoadingData=false；
}
@凌驾
小部件构建（构建上下文）{
打印（widget.query.length）；
扩大回报(
孩子：NotificationListener(
onNotification：（滚动通知滚动信息）{
if（scrollInfo.metrics.pixels==scrollInfo.metrics.maxScrollExtent&&isLoadingData==false）{
isLoadingData=true；
onBottomListReachedCallback（）；
}
返回true；
},
子项：ListView.builder(
填充：EdgeInsets.fromLTRB(
widget.configuration.screenWidth/20，
widget.configuration.screenWidth/40，
widget.configuration.screenWidth/20，
widget.configuration.screenWidth/40），
itemCount:widget.query.length，
itemBuilder：（BuildContext上下文，int itemIndex）{
返回showResultWidget（itemIndex）；
},
收缩膜：假，
),
),
);
}

编辑： 如所问，小部件是如何调用的：

import 'package:cloud_firestore/cloud_firestore.dart';
import 'package:flutter/material.dart';
import 'package:the_spot/services/database.dart';
import 'package:the_spot/services/library/configuration.dart';
import 'package:the_spot/services/library/userProfile.dart';
import 'package:the_spot/services/library/usersListView.dart';
import 'package:the_spot/theme.dart';


class FollowersFollowingFriendsPage extends StatefulWidget {
  final Configuration configuration;
  final UserProfile userProfile;
  final String type;

  const FollowersFollowingFriendsPage(
      {Key key, this.configuration, this.userProfile, this.type})
      : super(key: key);

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

class _FollowersFollowingFriendsPageState
    extends State<FollowersFollowingFriendsPage> {
  bool isWaiting = true;
  List<UserProfile> queryResult = [];
  Timestamp index = Timestamp.now();

  String noResultMessage;
  String appBarTitle;

  @override
  void initState() {
    super.initState();
    init();



  }

  void init() async {
    switch (widget.type) {
      case "Followers":
        {
          noResultMessage =
          "This user haven't been followed by anyone for the moment.";
          appBarTitle = "Users following " + widget.userProfile.pseudo;

          Map<String, Object> res = await Database().getFollowersOf(context, widget.configuration.userData.userId, widget.userProfile.userId, index, 10);

          queryResult.addAll(res['users']);
          index = res['lastTimestamp'];
          setState(() {
            isWaiting = false;
          });

        }
        break;

      case "Following":
        {
          noResultMessage = "This user doesn't follow anyone for the moment.";
          appBarTitle = "Users followed by " + widget.userProfile.pseudo;

          Map<String, Object> res = await Database().getFollowingOf(context, widget.configuration.userData.userId, widget.userProfile.userId, index, 4);

          queryResult.addAll(res['users']);

          index = res['lastTimestamp'];
          setState(() {
            isWaiting = false;
          });
        }
        break;
      case "Friends":
        {
          noResultMessage = "This user hasn't added friends yet.";
          appBarTitle = "Friends of " + widget.userProfile.pseudo;

          queryResult = await Database().getUsersByIds(context, widget.userProfile.friends, verifyIfFriendsOrFollowed: true, mainUserId: widget.userProfile.userId);
          setState(() {
            isWaiting = false;
          });
        }
        break;
    }
  }

  @override
  Widget build(BuildContext context) {
    return Scaffold(
      backgroundColor: PrimaryColorDark,
      appBar: AppBar(title: Text(appBarTitle),),
      body: Column(
        children: <Widget>[
          showQueryResultsWidget(),
        ],
      ),
    );
  }

  Widget showQueryResultsWidget() {
    if (isWaiting)
      return Padding(
          padding: EdgeInsets.only(top: widget.configuration.screenWidth / 20),
          child: Center(
            child: CircularProgressIndicator(),
          ));
    else if (queryResult.length == 0 || queryResult == null)
      return Padding(
        padding: EdgeInsets.only(top: widget.configuration.screenWidth / 20),
        child: Center(child: Text(noResultMessage)),
      );
    else
      return UsersListView(
        configuration: widget.configuration,
        query: queryResult,
        onBottomListReachedCallback: init,
      );
  }
}

import'包：cloud_firestore/cloud_firestore.dart'；
进口“包装：颤振/材料.省道”；
导入“包：_spot/services/database.dart”；
导入“包：_spot/services/library/configuration.dart”；
导入“package:the_spot/services/library/userProfile.dart”；
导入“包：_spot/services/library/usersListView.dart”；
导入“package:the_spot/theme.dart”；
类followersFollowFriendsPage扩展StatefulWidget{
最终配置；
最终用户配置文件用户配置文件；
最终字符串类型；
常数跟随者(
{Key Key，this.configuration，this.userProfile，this.type}）
：super（key:key）；
@凌驾
_FollowersFollowFriendsPagestate createState（）=>
_followers followers friendspagestate（）；
}
第_类跟随者
扩展状态{
bool isWaiting=true；
列表查询结果=[]；
Timestamp index=Timestamp.now（）；
字符串noResultMessage；
字符串appBarTitle；
@凌驾
void initState（）{
super.initState（）；
init（）；
}
void init（）异步{
开关（widget.type）{
“追随者”一案：
{
noResultMessage=
“目前还没有任何人跟踪此用户。”；
appBarTitle=“用户跟随”+widget.userProfile.pseudo；
Map res=await Database（）.getFollowersOf（上下文，widget.configuration.userData.userId，widget.userProfile.userId，索引，10）；
addAll（res['users']）；
索引=res['lastTimestamp']；
设置状态（）{
isWaiting=false；
});
}
打破
“以下”情况：
import 'package:cloud_firestore/cloud_firestore.dart';
import 'package:flutter/material.dart';
import 'package:the_spot/services/database.dart';
import 'package:the_spot/services/library/configuration.dart';
import 'package:the_spot/services/library/userProfile.dart';
import 'package:the_spot/services/library/usersListView.dart';
import 'package:the_spot/theme.dart';


class FollowersFollowingFriendsPage extends StatefulWidget {
  final Configuration configuration;
  final UserProfile userProfile;
  final String type;

  const FollowersFollowingFriendsPage(
      {Key key, this.configuration, this.userProfile, this.type})
      : super(key: key);

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

class _FollowersFollowingFriendsPageState
    extends State<FollowersFollowingFriendsPage> {
  bool isWaiting = true;
  List<UserProfile> queryResult = [];
  Timestamp index = Timestamp.now();

  String noResultMessage;
  String appBarTitle;

  @override
  void initState() {
    super.initState();
    init();



  }

  void init() async {
    switch (widget.type) {
      case "Followers":
        {
          noResultMessage =
          "This user haven't been followed by anyone for the moment.";
          appBarTitle = "Users following " + widget.userProfile.pseudo;

          Map<String, Object> res = await Database().getFollowersOf(context, widget.configuration.userData.userId, widget.userProfile.userId, index, 10);

          queryResult.addAll(res['users']);
          index = res['lastTimestamp'];
          setState(() {
            isWaiting = false;
          });

        }
        break;

      case "Following":
        {
          noResultMessage = "This user doesn't follow anyone for the moment.";
          appBarTitle = "Users followed by " + widget.userProfile.pseudo;

          Map<String, Object> res = await Database().getFollowingOf(context, widget.configuration.userData.userId, widget.userProfile.userId, index, 4);

          queryResult.addAll(res['users']);

          index = res['lastTimestamp'];
          setState(() {
            isWaiting = false;
          });
        }
        break;
      case "Friends":
        {
          noResultMessage = "This user hasn't added friends yet.";
          appBarTitle = "Friends of " + widget.userProfile.pseudo;

          queryResult = await Database().getUsersByIds(context, widget.userProfile.friends, verifyIfFriendsOrFollowed: true, mainUserId: widget.userProfile.userId);
          setState(() {
            isWaiting = false;
          });
        }
        break;
    }
  }

  @override
  Widget build(BuildContext context) {
    return Scaffold(
      backgroundColor: PrimaryColorDark,
      appBar: AppBar(title: Text(appBarTitle),),
      body: Column(
        children: <Widget>[
          showQueryResultsWidget(),
        ],
      ),
    );
  }

  Widget showQueryResultsWidget() {
    if (isWaiting)
      return Padding(
          padding: EdgeInsets.only(top: widget.configuration.screenWidth / 20),
          child: Center(
            child: CircularProgressIndicator(),
          ));
    else if (queryResult.length == 0 || queryResult == null)
      return Padding(
        padding: EdgeInsets.only(top: widget.configuration.screenWidth / 20),
        child: Center(child: Text(noResultMessage)),
      );
    else
      return UsersListView(
        configuration: widget.configuration,
        query: queryResult,
        onBottomListReachedCallback: init,
      );
  }
}

 void init() async {
switch (widget.type) {
  case "Followers":
  ....
  setState((){
   queryResult.addAll(res['users']);
   ...
 });