Flutter ScrollController 无法正常工作

问题描述

在我的 Flutter 应用程序中，我尝试使用 scrollController 在 listBuilder 中滚动列表视图，但 ScrollController 无法正常工作。它不显示错误或异常，但列表不滚动。即使我使用滚动控制器 jumpTo 或 animateto 它也不起作用。即使我在 animateto 和 jumpTo 中给出最大值，如 1000 和 20000，它也不会滚动。

import 'package:Flutter/gestures.dart';
import 'package:Flutter/material.dart';

class Class extends StatefulWidget {
final int data;
final List list;
Class({required this.data,required this.list});
@override
_Classstate createState() => _Classstate();
}

class _Classstate extends State<Class> with TickerProviderStateMixin {
late Animation<double> animation;
late AnimationController animationController;
late double height = 0;

final List lst = [
 [true,true,true],[false,false,false],[true,];

void initState() {
  super.initState();

animationController =
    AnimationController(vsync: this,duration: Duration(seconds: 5));

animation = Tween<double>(begin: 0,end: 200).animate(animationController)
  ..addListener(() {
    setState(() {});
  })
  ..addStatusListener((status) {});
animationController.forward();
 }

Widget container(data) {
return Stack(
  children: [
    GestureDetector(
      onTap: () {
        setState(() {
          animationController.forward();
        });
      },child: Transform.translate(
        offset: Offset(0,animation.value),child: Container(
          color: lst[data][0] ? Colors.black : Colors.transparent,height: MediaQuery.of(context).size.height / 4,width: MediaQuery.of(context).size.width / 4,child: Text('$data'),),],);
 }

 @override
 Widget build(BuildContext context) {
return container(widget.data);
  }

 @override
 void dispose() {
super.dispose();
animationController.dispose();
  }
 }

class Yes extends StatefulWidget {
 @override
_Yesstate createState() => _Yesstate();
  }

 class _Yesstate extends State<Yes> {
   List lst = [
[true,];

 ScrollController _scrollController = ScrollController();

 void initState() {
if (_scrollController.hasClients) {
  super.initState();
  // _scrollController.animateto(0,//     // _scrollController.offset + MediaQuery.of(context).size.height/6,//     duration: Duration(seconds: 2),//     curve: Curves.linear);
  _scrollController.jumpTo(_scrollController.position.maxScrollExtent);
    }
   }

 @override
 Widget build(BuildContext context) {
    return ListView(
  controller: _scrollController,//  physics: NeverScrollableScrollPhysics(),children: [
    ListView.builder(
          // physics: NeverScrollableScrollPhysics(),reverse: true,itemCount: lst.length,controller: _scrollController,itemBuilder: (BuildContext context,int position) {
          return Stack(children: [Class(data: position,list: lst)]);
        }),);
  }
   }

解决方法

你的代码不够清晰但是 试试这个，因为例子工作得很好

  runApp(MyApp());
}

class MyApp extends StatelessWidget {
  // This widget is the root of your application.
  @override
  Widget build(BuildContext context) {
    return MaterialApp(
      title: 'Flutter Demo',theme: ThemeData(

        primarySwatch: Colors.blue,),home: ListExample(),);
  }
}

class ListExample extends StatelessWidget {
  ListExample({Key? key}) : super(key: key);

  final ScrollController controller = ScrollController();
  double pos = 0;

  @override
  Widget build(BuildContext context) {
    return Scaffold(
      body: Column(
        children: [
          Expanded(
            child: ListView.builder(
              controller: controller,itemCount: 10000,itemBuilder: (context,index) {
                return Text('item $index');
              },ElevatedButton(
              onPressed: () {
                controller.jumpTo(pos+=250);
              },child: Text(' Jump'))
        ],);
  }
}

,

您必须附加侦听器来侦听 ScrollController 的位置以跟踪位置。像这个例子

 ScrollController _scrollController;

 double _lastEndOfScroll = 0;   

 _scrollController.addListener(() {

  double maxScroll = _scrollController.position.maxScrollExtent;
  double currentScroll = _scrollController.position.pixels;
  if (maxScroll == currentScroll) {
    if (_page < _totalPages - 1 && !_isFetchingData) {
      _lastEndOfScroll = maxScroll;
      _page++;
      print(_page.toString());
      search.filter.pageNumber = _page;
      fetchData(search.filter);
    }
  }
});

if (!_isFetchingData) _scrollController.jumpTo(_lastEndOfScroll);