ListView를 만들려고하는데 list_form.dart 클래스를 가져올 때이 오류가 발생합니다. 메인 파일 내에서 실행하려고하면이 오류가 발생하지 않기 때문에 레이아웃에 약간의 실수를했을 수도 있습니다.
이것은 오류입니다.
I/flutter (12956): ══╡ EXCEPTION CAUGHT BY RENDERING LIBRARY ╞═════════════════════════════════════════════════════════
I/flutter (12956): The following assertion was thrown during performResize():
I/flutter (12956): Vertical viewport was given unbounded height.
I/flutter (12956): Viewports expand in the scrolling direction to fill their container.In this case, a vertical
I/flutter (12956): viewport was given an unlimited amount of vertical space in which to expand. This situation
I/flutter (12956): typically happens when a scrollable widget is nested inside another scrollable widget.
I/flutter (12956): If this widget is always nested in a scrollable widget there is no need to use a viewport because
I/flutter (12956): there will always be enough vertical space for the children. In this case, consider using a Column
I/flutter (12956): instead. Otherwise, consider using the "shrinkWrap" property (or a ShrinkWrappingViewport) to size
I/flutter (12956): the height of the viewport to the sum of the heights of its children.
I/flutter (12956):
I/flutter (12956): When the exception was thrown, this was the stack:
I/flutter (12956): #0 RenderViewport.performResize.<anonymous closure> (package:flutter/src/rendering/viewport.dart:1133:15)
I/flutter (12956): #1 RenderViewport.performResize (package:flutter/src/rendering/viewport.dart:1186:6)
I/flutter (12956): #2 RenderObject.layout (package:flutter/src/rendering/object.dart:1616:9)
I/flutter (12956): #3 _RenderProxyBox&RenderBox&RenderObjectWithChildMixin&RenderProxyBoxMixin.performLayout (package:flutter/src/rendering/proxy_box.dart:108:13)
I/flutter (12956): #4 RenderObject.layout (package:flutter/src/rendering/object.dart:1631:7)
I/flutter (12956): #5 _RenderProxyBox&RenderBox&RenderObjectWithChildMixin&RenderProxyBoxMixin.performLayout (package:flutter/src/rendering/proxy_box.dart:108:13)
I/flutter (12956): #6 RenderObject.layout (package:flutter/src/rendering/object.dart:1631:7)
I/flutter (12956): #7 _RenderProxyBox&RenderBox&RenderObjectWithChildMixin&RenderProxyBoxMixin.performLayout (package:flutter/src/rendering/proxy_box.dart:108:13)
I/flutter (12956): #8 RenderObject.layout (package:flutter/src/rendering/object.dart:1631:7)
I/flutter (12956): #9 _RenderProxyBox&RenderBox&RenderObjectWithChildMixin&RenderProxyBoxMixin.performLayout (package:flutter/src/rendering/proxy_box.dart:108:13)
I/flutter (12956): #10 RenderObject.layout (package:flutter/src/rendering/object.dart:1631:7)
I/flutter (12956): #11 _RenderProxyBox&RenderBox&RenderObjectWithChildMixin&RenderProxyBoxMixin.performLayout (package:flutter/src/rendering/proxy_box.dart:108:13)
I/flutter (12956): #12 RenderObject.layout (package:flutter/src/rendering/object.dart:1631:7)
I/flutter (12956): #13 _RenderProxyBox&RenderBox&RenderObjectWithChildMixin&RenderProxyBoxMixin.performLayout (package:flutter/src/rendering/proxy_box.dart:108:13)
I/flutter (12956): #14 RenderObject.layout (package:flutter/src/rendering/object.dart:1631:7)
I/flutter (12956): #15 _RenderProxyBox&RenderBox&RenderObjectWithChildMixin&RenderProxyBoxMixin.performLayout (package:flutter/src/rendering/proxy_box.dart:108:13)
I/flutter (12956): #16 RenderObject.layout (package:flutter/src/rendering/object.dart:1631:7)
I/flutter (12956): #17 _RenderProxyBox&RenderBox&RenderObjectWithChildMixin&RenderProxyBoxMixin.performLayout (package:flutter/src/rendering/proxy_box.dart:108:13)
I/flutter (12956): #18 RenderObject.layout (package:flutter/src/rendering/object.dart:1631:7)
I/flutter (12956): #19 RenderFlex.performLayout (package:flutter/src/rendering/flex.dart:738:15)
I/flutter (12956): #20 RenderObject.layout (package:flutter/src/rendering/object.dart:1631:7)
I/flutter (12956): #21 RenderFlex.performLayout (package:flutter/src/rendering/flex.dart:738:15)
I/flutter (12956): #22 RenderObject.layout (package:flutter/src/rendering/object.dart:1631:7)
I/flutter (12956): #23 RenderPositionedBox.performLayout (package:flutter/src/rendering/shifted_box.dart:381:13)
I/flutter (12956): #24 RenderObject.layout (package:flutter/src/rendering/object.dart:1631:7)
I/flutter (12956): #25 MultiChildLayoutDelegate.layoutChild (package:flutter/src/rendering/custom_layout.dart:141:11)
I/flutter (12956): #26 _ScaffoldLayout.performLayout (package:flutter/src/material/scaffold.dart:339:7)
I/flutter (12956): #27 MultiChildLayoutDelegate._callPerformLayout (package:flutter/src/rendering/custom_layout.dart:211:7)
I/flutter (12956): #28 RenderCustomMultiChildLayoutBox.performLayout (package:flutter/src/rendering/custom_layout.dart:355:14)
I/flutter (12956): #29 RenderObject.layout (package:flutter/src/rendering/object.dart:1631:7)
I/flutter (12956): #30 _RenderProxyBox&RenderBox&RenderObjectWithChildMixin&RenderProxyBoxMixin.performLayout (package:flutter/src/rendering/proxy_box.dart:108:13)
I/flutter (12956): #31 RenderObject.layout (package:flutter/src/rendering/object.dart:1631:7)
I/flutter (12956): #32 _RenderProxyBox&RenderBox&RenderObjectWithChildMixin&RenderProxyBoxMixin.performLayout (package:flutter/src/rendering/proxy_box.dart:108:13)
I/flutter (12956): #33 _RenderCustomClip.performLayout (package:flutter/src/rendering/proxy_box.dart:1192:11)
I/flutter (12956): #34 RenderObject.layout (package:flutter/src/rendering/object.dart:1631:7)
I/flutter (12956): #35 _RenderProxyBox&RenderBox&RenderObjectWithChildMixin&RenderProxyBoxMixin.performLayout (package:flutter/src/rendering/proxy_box.dart:108:13)
I/flutter (12956): #36 RenderObject.layout (package:flutter/src/rendering/object.dart:1631:7)
I/flutter (12956): #37 _RenderProxyBox&RenderBox&RenderObjectWithChildMixin&RenderProxyBoxMixin.performLayout (package:flutter/src/rendering/proxy_box.dart:108:13)
I/flutter (12956): #38 _RenderCustomClip.performLayout (package:flutter/src/rendering/proxy_box.dart:1192:11)
I/flutter (12956): #39 RenderObject.layout (package:flutter/src/rendering/object.dart:1631:7)
I/flutter (12956): #40 _RenderProxyBox&RenderBox&RenderObjectWithChildMixin&RenderProxyBoxMixin.performLayout (package:flutter/src/rendering/proxy_box.dart:108:13)
I/flutter (12956): #41 RenderObject.layout (package:flutter/src/rendering/object.dart:1631:7)
I/flutter (12956): #42 _RenderProxyBox&RenderBox&RenderObjectWithChildMixin&RenderProxyBoxMixin.performLayout (package:flutter/src/rendering/proxy_box.dart:108:13)
I/flutter (12956): #43 RenderObject.layout (package:flutter/src/rendering/object.dart:1631:7)
I/flutter (12956): #44 _RenderProxyBox&RenderBox&RenderObjectWithChildMixin&RenderProxyBoxMixin.performLayout (package:flutter/src/rendering/proxy_box.dart:108:13)
I/flutter (12956): #45 RenderObject.layout (package:flutter/src/rendering/object.dart:1631:7)
I/flutter (12956): #46 _RenderProxyBox&RenderBox&RenderObjectWithChildMixin&RenderProxyBoxMixin.performLayout (package:flutter/src/rendering/proxy_box.dart:108:13)
I/flutter (12956): #47 RenderObject.layout (package:flutter/src/rendering/object.dart:1631:7)
I/flutter (12956): #48 _RenderProxyBox&RenderBox&RenderObjectWithChildMixin&RenderProxyBoxMixin.performLayout (package:flutter/src/rendering/proxy_box.dart:108:13)
I/flutter (12956): #49 RenderObject.layout (package:flutter/src/rendering/object.dart:1631:7)
I/flutter (12956): #50 _RenderProxyBox&RenderBox&RenderObjectWithChildMixin&RenderProxyBoxMixin.performLayout (package:flutter/src/rendering/proxy_box.dart:108:13)
I/flutter (12956): #51 RenderObject.layout (package:flutter/src/rendering/object.dart:1631:7)
I/flutter (12956): #52 _RenderProxyBox&RenderBox&RenderObjectWithChildMixin&RenderProxyBoxMixin.performLayout (package:flutter/src/rendering/proxy_box.dart:108:13)
I/flutter (12956): #53 RenderObject.layout (package:flutter/src/rendering/object.dart:1631:7)
I/flutter (12956): #54 _RenderProxyBox&RenderBox&RenderObjectWithChildMixin&RenderProxyBoxMixin.performLayout (package:flutter/src/rendering/proxy_box.dart:108:13)
I/flutter (12956): #55 RenderOffstage.performLayout (package:flutter/src/rendering/proxy_box.dart:2884:13)
I/flutter (12956): #56 RenderObject.layout (package:flutter/src/rendering/object.dart:1631:7)
I/flutter (12956): #57 RenderStack.performLayout (package:flutter/src/rendering/stack.dart:520:15)
I/flutter (12956): #58 RenderObject.layout (package:flutter/src/rendering/object.dart:1631:7)
I/flutter (12956): #59 __RenderTheatre&RenderBox&RenderObjectWithChildMixin&RenderProxyBoxMixin.performLayout (package:flutter/src/rendering/proxy_box.dart:108:13)
I/flutter (12956): #60 RenderObject.layout (package:flutter/src/rendering/object.dart:1631:7)
I/flutter (12956): #61 _RenderProxyBox&RenderBox&RenderObjectWithChildMixin&RenderProxyBoxMixin.performLayout (package:flutter/src/rendering/proxy_box.dart:108:13)
I/flutter (12956): #62 RenderObject.layout (package:flutter/src/rendering/object.dart:1631:7)
I/flutter (12956): #63 _RenderProxyBox&RenderBox&RenderObjectWithChildMixin&RenderProxyBoxMixin.performLayout (package:flutter/src/rendering/proxy_box.dart:108:13)
I/flutter (12956): #64 RenderObject.layout (package:flutter/src/rendering/object.dart:1631:7)
I/flutter (12956): #65 _RenderProxyBox&RenderBox&RenderObjectWithChildMixin&RenderProxyBoxMixin.performLayout (package:flutter/src/rendering/proxy_box.dart:108:13)
I/flutter (12956): #66 RenderObject.layout (package:flutter/src/rendering/object.dart:1631:7)
I/flutter (12956): #67 _RenderProxyBox&RenderBox&RenderObjectWithChildMixin&RenderProxyBoxMixin.performLayout (package:flutter/src/rendering/proxy_box.dart:108:13)
I/flutter (12956): #68 RenderObject.layout (package:flutter/src/rendering/object.dart:1631:7)
I/flutter (12956): #69 _RenderProxyBox&RenderBox&RenderObjectWithChildMixin&RenderProxyBoxMixin.performLayout (package:flutter/src/rendering/proxy_box.dart:108:13)
I/flutter (12956): #70 RenderObject.layout (package:flutter/src/rendering/object.dart:1631:7)
I/flutter (12956): #71 RenderView.performLayout (package:flutter/src/rendering/view.dart:147:13)
I/flutter (12956): #72 RenderObject._layoutWithoutResize (package:flutter/src/rendering/object.dart:1506:7)
I/flutter (12956): #73 PipelineOwner.flushLayout (package:flutter/src/rendering/object.dart:765:18)
I/flutter (12956): #74 _WidgetsFlutterBinding&BindingBase&GestureBinding&ServicesBinding&SchedulerBinding&PaintingBinding&SemanticsBinding&RendererBinding.drawFrame (package:flutter/src/rendering/binding.dart:270:19)
I/flutter (12956): #75 _WidgetsFlutterBinding&BindingBase&GestureBinding&ServicesBinding&SchedulerBinding&PaintingBinding&SemanticsBinding&RendererBinding&WidgetsBinding.drawFrame (package:flutter/src/widgets/binding.dart:674:13)
I/flutter (12956): #76 _WidgetsFlutterBinding&BindingBase&GestureBinding&ServicesBinding&SchedulerBinding&PaintingBinding&SemanticsBinding&RendererBinding._handlePersistentFrameCallback (package:flutter/src/rendering/binding.dart:208:5)
I/flutter (12956): #77 _WidgetsFlutterBinding&BindingBase&GestureBinding&ServicesBinding&SchedulerBinding._invokeFrameCallback (package:flutter/src/scheduler/binding.dart:990:15)
I/flutter (12956): #78 _WidgetsFlutterBinding&BindingBase&GestureBinding&ServicesBinding&SchedulerBinding.handleDrawFrame (package:flutter/src/scheduler/binding.dart:930:9)
I/flutter (12956): #79 _WidgetsFlutterBinding&BindingBase&GestureBinding&ServicesBinding&SchedulerBinding.scheduleWarmUpFrame.<anonymous closure> (package:flutter/src/scheduler/binding.dart:751:7)
I/flutter (12956): #81 _Timer._runTimers (dart:isolate/runtime/libtimer_impl.dart:382:19)
I/flutter (12956): #82 _Timer._handleMessage (dart:isolate/runtime/libtimer_impl.dart:416:5)
I/flutter (12956): #83 _RawReceivePortImpl._handleMessage (dart:isolate/runtime/libisolate_patch.dart:171:12)
I/flutter (12956): (elided one frame from package dart:async)
I/flutter (12956):
I/flutter (12956): The following RenderObject was being processed when the exception was fired:
I/flutter (12956): RenderViewport#925a8 NEEDS-LAYOUT NEEDS-PAINT
I/flutter (12956): creator: Viewport ← _ScrollableScope ← IgnorePointer-[GlobalKey#8e8f7] ← Semantics ← Listener ←
I/flutter (12956): _GestureSemantics ← RawGestureDetector-[LabeledGlobalKey<RawGestureDetectorState>#67ae5] ←
I/flutter (12956): _ScrollSemantics-[GlobalKey#17eb8] ← RepaintBoundary ← CustomPaint ← RepaintBoundary ←
I/flutter (12956): NotificationListener<ScrollNotification> ← ⋯
I/flutter (12956): parentData: <none> (can use size)
I/flutter (12956): constraints: BoxConstraints(unconstrained)
I/flutter (12956): size: MISSING
I/flutter (12956): axisDirection: down
I/flutter (12956): crossAxisDirection: right
I/flutter (12956): offset: ScrollPositionWithSingleContext#c4917(offset: 0.0, range: null..null, viewport: null,
I/flutter (12956): ScrollableState, AlwaysScrollableScrollPhysics -> ClampingScrollPhysics, IdleScrollActivity#2fecf,
I/flutter (12956): ScrollDirection.idle)
I/flutter (12956): anchor: 0.0
I/flutter (12956): This RenderObject had the following descendants (showing up to depth 5):
I/flutter (12956): RenderSliverPadding#74d62 NEEDS-LAYOUT NEEDS-PAINT
I/flutter (12956): RenderSliverList#5c56d NEEDS-LAYOUT NEEDS-PAINT
I/flutter (12956): ════════════════════════════════════════════════════════════════════════════════════════════════════
I/flutter (12956): Another exception was thrown: RenderBox was not laid out: RenderViewport#925a8 NEEDS-LAYOUT NEEDS-PAINT
I/flutter (12956): Another exception was thrown: RenderBox was not laid out: RenderViewport#925a8 NEEDS-PAINT
I/flutter (12956): Another exception was thrown: RenderBox was not laid out: RenderIgnorePointer#8bbda relayoutBoundary=up11 NEEDS-PAINT
I/flutter (12956): Another exception was thrown: RenderBox was not laid out: RenderSemanticsAnnotations#209b4 relayoutBoundary=up10 NEEDS-PAINT
I/flutter (12956): Another exception was thrown: RenderBox was not laid out: RenderPointerListener#a9641 relayoutBoundary=up9 NEEDS-PAINT
I/flutter (12956): Another exception was thrown: RenderBox was not laid out: RenderSemanticsGestureHandler#9f5b4 relayoutBoundary=up8 NEEDS-PAINT
I/flutter (12956): Another exception was thrown: RenderBox was not laid out: _RenderScrollSemantics#47944 relayoutBoundary=up7 NEEDS-PAINT
I/flutter (12956): Another exception was thrown: RenderBox was not laid out: RenderRepaintBoundary#e17a8 relayoutBoundary=up6 NEEDS-PAINT
I/flutter (12956): Another exception was thrown: RenderBox was not laid out: RenderCustomPaint#a2328 relayoutBoundary=up5 NEEDS-PAINT
I/flutter (12956): Another exception was thrown: RenderBox was not laid out: RenderRepaintBoundary#02607 relayoutBoundary=up4 NEEDS-PAINT
I/flutter (12956): Another exception was thrown: RenderBox was not laid out: RenderFlex#79164 relayoutBoundary=up3 NEEDS-PAINT
I/flutter (12956): Another exception was thrown: 'package:flutter/src/rendering/shifted_box.dart': Failed assertion: line 310 pos 12: 'child.hasSize': is not true.
I/flutter (12956): Another exception was thrown: NoSuchMethodError: The method '<=' was called on null.
이것은 list_form.dart 클래스입니다.
import 'package:flutter/material.dart';
class ListForm extends StatefulWidget {
@override
ListFormState createState() => new ListFormState();
}
class ListFormState extends State<ListForm> {
List<String> products = ["Test1", "Test2", "Test3"];
@override
Widget build(BuildContext context) {
return new Container(
child: new Center(
child: new Column(
children: <Widget>[
new Row(
children: <Widget>[
new ListView.builder(
itemCount: products.length,
itemBuilder: (BuildContext ctxt, int index) {
return new Text(products[index]);
}
),
new IconButton(
icon: Icon(Icons.remove_circle),
onPressed: () { },
)
],
mainAxisAlignment: MainAxisAlignment.spaceBetween,
),
new TextField(
decoration: new InputDecoration(
hintText: "Prodotto"
),
onSubmitted: (String str) {
setState(() {
products.add(str);
});
},
),
]
)
)
);
}
}
이것은 app_base.dart 클래스입니다.
import 'package:flutter/material.dart';
import '../UI/list_form.dart';
class AppBase extends StatefulWidget {
@override
State createState() => new AppBaseState();
}
class AppBaseState extends State<AppBase> {
bool _pressed = true;
@override
Widget build(BuildContext context) {
return new Material(
color: Colors.greenAccent,
child: new Scaffold(
body:
new ListForm(),
appBar: AppBar(
centerTitle: true,
title: const Text('Skeeper'),
backgroundColor: Colors.green,
),
floatingActionButton: FloatingActionButton(
tooltip: 'Test',
child: new Icon(Icons.add),
backgroundColor: Colors.green,
onPressed: () {
setState(() {
_pressed = !_pressed;
});
},
),
)
);
}
}
사용하지 않는 코드가 있어도 걱정하지 마십시오. 진행중인 작업이며이 오류로 인해 제가하고있는 작업을 계속할 수 없습니다.
답변
문제는 ListView열 / 행 내부에 배치한다는 것 입니다. 예외의 텍스트는 오류에 대한 좋은 설명을 제공합니다.
오류를 방지하려면 ListView내부에 크기를 제공해야합니다 .
Expanded가로 크기 (최대 사용 가능)와 SizedBox(컨테이너가 될 수 있음)을 알리기 위해 를 사용하는이 코드를 제안합니다 .height:
new Row(
children: <Widget>[
Expanded(
child: SizedBox(
height: 200.0,
child: new ListView.builder(
scrollDirection: Axis.horizontal,
itemCount: products.length,
itemBuilder: (BuildContext ctxt, int index) {
return new Text(products[index]);
},
),
),
),
new IconButton(
icon: Icon(Icons.remove_circle),
onPressed: () {},
),
],
mainAxisAlignment: MainAxisAlignment.spaceBetween,
)
,
답변
다음과 같은 코드를 추가 할 수 있습니다.
ListView.builder{
shrinkWrap: true,
}
답변
오류 이유 :
Column세로 축에서 확장을 시도하고 ListView,. 따라서의 높이를 제한해야합니다 ListView.
솔루션
-
에서 왼쪽 전체 공간을 차지 하도록 허용 하려면
Expanded또는을 사용하십시오 .FlexibleListViewColumnColumn( children: <Widget>[ Expanded( child: ListView(...), ) ], )
-
SizedBox의 크기를ListView특정 높이 로 제한하려는 경우 사용 합니다 .Column( children: <Widget>[ SizedBox( height: 200, // constrain height child: ListView(), ) ], )
-
너무 크지 않은
shrinkWrap경우를 사용하십시오ListView.Column( children: <Widget>[ ListView( shrinkWrap: true, // use it ) ], )
답변
이 코드를 사용하여 가로 목록에 항목을 표시하는 문제를 해결했습니다.
new Container(
height: 20,
child: Row(
mainAxisAlignment: MainAxisAlignment.end,
children: <Widget>[
ListView.builder(
scrollDirection: Axis.horizontal,
shrinkWrap: true,
itemCount: array.length,
itemBuilder: (context, index){
return array[index];
},
),
],
),
);
답변
목록보기를 Flexible 위젯에 배치하는 것도 도움이 될 수 있습니다.
Flexible( fit: FlexFit.tight, child: _buildYourListWidget(..),)
답변
확장 된 위젯으로 ListView 래핑
Expanded(child:MyListView())
답변
