Flutter 未处理的异常ScrollController未附加到任何滚动视图
我总是犯这样的错误,不明白为什么会发生这种情况。该应用程序启动得非常好,但当我尝试登录时,它会阻塞并抛出此错误。有人能告诉我我做错了什么吗Flutter 未处理的异常ScrollController未附加到任何滚动视图,flutter,exception,scrollview,Flutter,Exception,Scrollview,我总是犯这样的错误,不明白为什么会发生这种情况。该应用程序启动得非常好,但当我尝试登录时,它会阻塞并抛出此错误。有人能告诉我我做错了什么吗 E/flutter ( 3070): [ERROR:flutter/lib/ui/ui_dart_state.cc(157)] Unhandled Exception: 'package:flutter/src/widgets/scroll_controller.dart': Failed assertion: line 110 pos 12: '_posi
E/flutter ( 3070): [ERROR:flutter/lib/ui/ui_dart_state.cc(157)] Unhandled Exception: 'package:flutter/src/widgets/scroll_controller.dart': Failed assertion: line 110 pos 12: '_positions.isNotEmpty': ScrollController not attached to any scroll views.
[38;5;244mE/flutter ( 3070): #0 _AssertionError._doThrowNew (dart:core-patch/errors_patch.dart:42:39)[39;49m
[38;5;244mE/flutter ( 3070): #1 _AssertionError._throwNew (dart:core-patch/errors_patch.dart:38:5)[39;49m
[38;5;244mE/flutter ( 3070): #2 ScrollController.position[39;49m
[38;5;244mE/flutter ( 3070): #3 PageController.animateToPage[39;49m
[38;5;248mE/flutter ( 3070): #4 _PreviewMobilePortraitState.initState.<anonymous closure>[39;49m
[38;5;244mE/flutter ( 3070): #5 _rootRunUnary (dart:async/zone.dart:1134:38)[39;49m
[38;5;244mE/flutter ( 3070): #6 _CustomZone.runUnary (dart:async/zone.dart:1031:19)[39;49m
[38;5;244mE/flutter ( 3070): #7 _CustomZone.runUnaryGuarded (dart:async/zone.dart:933:7)[39;49m
[38;5;244mE/flutter ( 3070): #8 _CustomZone.bindUnaryCallbackGuarded.<anonymous closure> (dart:async/zone.dart:970:26)[39;49m
[38;5;244mE/flutter ( 3070): #9 _rootRunUnary (dart:async/zone.dart:1138:13)[39;49m
[38;5;244mE/flutter ( 3070): #10 _CustomZone.runUnary (dart:async/zone.dart:1031:19)[39;49m
[38;5;244mE/flutter ( 3070): #11 _CustomZone.bindUnaryCallback.<anonymous closure> (dart:async/zone.dart:954:26)[39;49m
[38;5;244mE/flutter ( 3070): #12 _Timer._runTimers (dart:isolate-patch/timer_impl.dart:384:19)[39;49m
[38;5;244mE/flutter ( 3070): #13 _Timer._handleMessage (dart:isolate-patch/timer_impl.dart:418:5)[39;49m
[38;5;244mE/flutter ( 3070): #14 _RawReceivePortImpl._handleMessage (dart:isolate-patch/isolate_patch.dart:174:12)[39;49m
E/flatter(3070):[ERROR:flatter/lib/ui/ui\u dart\u state.cc(157)]未处理的异常:“package:flatter/src/widgets/scroll\u controller.dart”:失败的断言:第110行位置12:“\u positions.isNotEmpty”:ScrollController未附加到任何滚动视图。
[38;5;244mE/颤振(3070):#0#断言错误。(省道:核心补丁/错误(省道:42:39)[39;49米
[38;5;244mE/颤振(3070):#1#断言错误。(飞镖:核心补丁/错误补丁。飞镖:38:5)[39;49米
[38;5;244mE/颤振(3070):#2控制器。位置[39;49m
[38;5;244mE/颤振(3070):#3页控制器。动画网页[39;49m
[38;5;248mE/颤振(3070):#4#u预览移动端口状态。初始状态。[39;49m
[38;5;244mE/flatter(3070):#5#rootrunary(dart:async/zone.dart:1134:38)[39;49m
[38;5;244mE/flatter(3070):#6_CustomZone.runUnary(dart:async/zone.dart:1031:19)[39;49m
[38;5;244mE/颤振(3070):#7_CustomZone.runUnaryGuarded(dart:async/zone.dart:933:7)[39;49m
[38;5;244mE/flatter(3070):#8_CustomZone.bindunarycallbackguared。(dart:async/zone.dart:970:26)[39;49m
[38;5;244mE/颤振(3070):#9#rootrunary(dart:async/zone.dart:1138:13)[39;49m
[38;5;244mE/flatter(3070):#10_CustomZone.runUnary(dart:async/zone.dart:1031:19)[39;49m
[38;5;244mE/flatter(3070):#11_CustomZone.bindUnaryCallback.(dart:async/zone.dart:954:26)[39;49m]
[38;5;244mE/flatter(3070):#12_计时器。_运行计时器(dart:isolate patch/Timer_impl.dart:384:19)[39;49m
[38;5;244mE/flatter(3070):#13_Timer._handleMessage(省道:隔离补丁/定时器_impl.省道:418:5)[39;49m
[38;5;244mE/颤振(3070):#14#RawReceivePortImpl.(飞镖:隔离补丁/隔离补丁。飞镖:174:12)[39;49米
我在PreviewMobilePortraitState中的代码如下所示:
@override
void initState() {
super.initState();
//cycle through pages
Timer.periodic(Duration(seconds: 4), (Timer timer) {
if (_currentPage < 3) {
_currentPage++;
} else {
_currentPage = 0;
}
_pageController.animateToPage(
_currentPage,
duration: Duration(milliseconds: 400),
curve: Curves.easeInCubic,
);
});
}
@覆盖
void initState(){
super.initState();
//翻页
定时(持续时间(秒:4),(定时){
如果(当前页面<3){
_currentPage++;
}否则{
_currentPage=0;
}
_pageController.animateToPage(
_当前页,
持续时间:持续时间(毫秒:400),
曲线:Curves.easeInCubic,
);
});
}
调用\u pageController.animateToPage
您可以使用addPostFrameCallback
并选中\u pageController.hasClients
代码片段
@override
void initState() {
super.initState();
WidgetsBinding.instance.addPostFrameCallback((_) {
Timer.periodic(Duration(seconds: 4), (Timer timer) {
if (_currentPage < 3) {
_currentPage++;
} else {
_currentPage = 0;
}
if(_pageController.hasClients) {
_pageController.animateToPage(
_currentPage,
duration: Duration(milliseconds: 400),
curve: Curves.easeInCubic,
);
}
});
});
}
@覆盖
void initState(){
super.initState();
WidgetsBinding.instance.addPostFrameCallback((){
定时(持续时间(秒:4),(定时){
如果(当前页面<3){
_currentPage++;
}否则{
_currentPage=0;
}
if(_pageController.hasClients){
_pageController.animateToPage(
_当前页,
持续时间:持续时间(毫秒:400),
曲线:Curves.easeInCubic,
);
}
});
});
}
正在进行演示以模拟此案例
完整测试代码
import 'package:flutter/material.dart';
import 'dart:async';
class Feature {
String name;
Color color;
String header;
String subHeader;
String imgUrl;
Feature({this.name, this.color, this.header, this.subHeader, this.imgUrl});
}
List<Feature> featuredList = [
Feature(
name: "a",
color: Colors.pink,
header: "ah",
subHeader: "a sub",
imgUrl: "https://picsum.photos/250?image=9"),
Feature(
name: "b",
color: Colors.blue,
header: "bh",
subHeader: "b sub",
imgUrl: "https://picsum.photos/250?image=10"),
Feature(
name: "c",
color: Colors.yellow,
header: "ch",
subHeader: "c sub",
imgUrl: "https://picsum.photos/250?image=11")
];
class WidgetFeatured extends StatefulWidget {
@override
_WidgetFeaturedState createState() => _WidgetFeaturedState();
}
class _WidgetFeaturedState extends State<WidgetFeatured> {
int _currentPage = 0;
final PageController _pageController = PageController(
initialPage: 0,
);
@override
void initState() {
super.initState();
WidgetsBinding.instance.addPostFrameCallback((_) {
Timer.periodic(Duration(seconds: 4), (Timer timer) {
if (_currentPage < 3) {
_currentPage++;
} else {
_currentPage = 0;
}
if(_pageController.hasClients) {
_pageController.animateToPage(
_currentPage,
duration: Duration(milliseconds: 400),
curve: Curves.easeInCubic,
);
}
});
});
}
@override
void dispose() {
super.dispose();
_pageController.dispose();
}
_onPageChanged(int index) {
setState(() {
_currentPage = index;
});
}
@override
Widget build(BuildContext context) {
return Container(
height: 200,
child: PageView.builder(
physics: BouncingScrollPhysics(),
scrollDirection: Axis.horizontal,
controller: _pageController,
onPageChanged: _onPageChanged,
itemBuilder: (context, index) => WidgetFeaturedItem(index),
itemCount: featuredList.length,
),
);
}
}
class WidgetFeaturedItem extends StatelessWidget {
final int indexItem;
WidgetFeaturedItem(this.indexItem);
@override
Widget build(BuildContext context) {
return Container(
padding: const EdgeInsets.all(20),
color: featuredList[indexItem].color,
width: double.infinity,
height: 180,
child: Stack(
children: <Widget>[
Row(
children: <Widget>[
Column(
mainAxisAlignment: MainAxisAlignment.center,
children: <Widget>[
Text(
featuredList[indexItem].header,
style: TextStyle(
fontSize: 20,
fontWeight: FontWeight.bold,
color: Colors.white,
),
),
Text(
featuredList[indexItem].subHeader,
style: TextStyle(
fontSize: 16,
fontWeight: FontWeight.bold,
color: Colors.white,
),
),
FlatButton(
onPressed: () {},
padding: const EdgeInsets.symmetric(
horizontal: 15,
vertical: 3,
),
color: Theme.of(context).primaryColor,
child: Text(
'Order now',
style: TextStyle(
color: Colors.white,
fontSize: 12,
fontWeight: FontWeight.w100,
),
),
),
],
),
Image.network(
featuredList[indexItem].imgUrl,
height: 120,
width: 120,
//width: 335,
fit: BoxFit.cover,
),
],
)
],
),
);
}
}
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 _MyHomePageState extends State<MyHomePage> {
int _counter = 0;
void _incrementCounter() {
setState(() {
_counter++;
});
}
@override
Widget build(BuildContext context) {
return Scaffold(
appBar: AppBar(
title: Text(widget.title),
),
body: Center(
child: Column(
mainAxisAlignment: MainAxisAlignment.center,
children: <Widget>[
Expanded(child: WidgetFeatured()),
Text(
'You have pushed the button this many times:',
),
Text(
'$_counter',
style: Theme.of(context).textTheme.headline4,
),
],
),
),
floatingActionButton: FloatingActionButton(
onPressed: _incrementCounter,
tooltip: 'Increment',
child: Icon(Icons.add),
),
);
}
}
导入“包装:颤振/材料.省道”;
导入“dart:async”;
类特征{
字符串名;
颜色;
字符串头;
字符串副标题;
字符串imgUrl;
功能({this.name,this.color,this.header,this.subHeader,this.imgUrl});
}
列表功能列表=[
特征(
名称:“a”,
颜色:颜色。粉红色,
标题:“啊”,
副标题:"潜艇",,
imgUrl:“https://picsum.photos/250?image=9"),
特征(
名称:“b”,
颜色:颜色,蓝色,
标题:“bh”,
副标题:"b sub",
imgUrl:“https://picsum.photos/250?image=10"),
特征(
名称:“c”,
颜色:颜色,黄色,
标题:“ch”,
副标题:"丙类副标题",
imgUrl:“https://picsum.photos/250?image=11")
];
类WidgetFeatured扩展StatefulWidget{
@凌驾
_WidgetFeaturedState createState()=>\u WidgetFeaturedState();
}
类_WidgetFeaturedState扩展状态{
int _currentPage=0;
最终页面控制器_PageController=PageController(
初始页:0,
);
@凌驾
void initState(){
super.initState();
WidgetsBinding.instance.addPostFrameCallback((){
定时(持续时间(秒:4),(定时){
如果(当前页面<3){
_currentPage++;
}否则{
_currentPage=0;
}
if(_pageController.hasClients){
_pageController.animateToPage(
_当前页,
持续时间:持续时间(毫秒:400),
曲线:Curves.easeInCubic,
);
}
});
});
}
@凌驾
无效处置(){
super.dispose();
_pageController.dispose();
}
_onPageChanged(整型索引){
设置状态(){
_currentPage=索引;
});
}
@凌驾
小部件构建(构建上下文){
返回容器(
身高:200,
子项:PageView.builder(
物理:弹跳CrollPhysics(),
滚动方向:轴水平,
控制器:_pageController,
onPageChanged:_onPageChanged,
itemBuilder:(上下文,索引)=>WidgetFeaturedItem(索引),
itemCount:featuredList.length,
),
);
}
}
类WidgetFeaturedItem扩展了无状态小部件{
最终int索引项;
WidgetFeaturedItem(this.indexItem);
@凌驾
小部件构建(构建上下文){
返回容器(
填充:常数边集。全部(20),
颜色:featuredList[indexItem]。颜色,
宽度:double.infinity,
身高:180,
子:堆栈(
儿童:[
划船(
儿童:[
纵队(
mainAxisAlignment:mainAxisAlignment.center,
儿童:[
正文(