如何在Expanded中使用SingleChildScrollView？我有一个屏幕，显示Image.network，ListView.builder和Row(TextFormField和IconButton)。我用ListView包装了Expanded。如何用SingleChildScrollView包装此列？打开键盘时，我需要移动屏幕以查看我在写什么。当我包装我的专栏时，我有此错误。
body: SingleChildScrollView(
child: Column(
children: <Widget>[
Container(
child: GestureDetector(
child:
Image.network(
postOne.imageUrl,
fit: BoxFit.fitWidth,
height: MediaQuery
.of(context)
.size
.width,
width: MediaQuery
.of(context)
.size
.width,
),
onLongPress: () {},
onDoubleTap: () {},
),
),
Expanded(
//height: MediaQuery.of(context).size.width*0.33,
child: ListView.builder(
itemCount: commentList.length,
itemBuilder: (context, position) {
return GestureDetector(
onLongPress: () {},
child: Card(
child: Padding(
padding: EdgeInsets.all(5.0),
child: new CheckboxListTile(
title: new Text(commentList
.elementAt(position)
.coment,
style: TextStyle(fontSize: 18.0),),
value: values[commentList
.elementAt(position)
.coment],
onChanged: (bool value) {}),
),
)
);
}
),
),
Container(
child: Row(
crossAxisAlignment: CrossAxisAlignment.start,
children: [
new Flexible(
child: Theme(
data: new ThemeData(
brightness: Brightness.light,
primarySwatch: Colors.grey,
inputDecorationTheme: new InputDecorationTheme(
labelStyle: new TextStyle(
color: Colors.black45, fontSize: 18.0
),
)
),
child: new Form(
key: _formKey,
child: new TextFormField(
validator: (value) {
if (value.isEmpty) {
return 'Please enter the comment';
}
},
controller: commentController,
decoration: new InputDecoration(
labelText: "Add comment",
//hintText: 'Add comment'
),
keyboardType: TextInputType.text,
),
),
),
),
new Container(
margin: EdgeInsets.only(left: 10.0, top: 12.0),
child: new IconButton(
icon: new Icon(Icons.send, color: Colors.black,),
onPressed: () {}
)
),
]),
),
],
),
),
I/flutter ( 6816): ══╡ EXCEPTION CAUGHT BY RENDERING LIBRARY ╞═════════════════════════════════════════════════════════
I/flutter ( 6816): The following assertion was thrown during performLayout():
I/flutter ( 6816): RenderFlex children have non-zero flex but incoming height constraints are unbounded.
I/flutter ( 6816): When a column is in a parent that does not provide a finite height constraint, for example if it is
I/flutter ( 6816): in a vertical scrollable, it will try to shrink-wrap its children along the vertical axis. Setting a
I/flutter ( 6816): flex on a child (e.g. using Expanded) indicates that the child is to expand to fill the remaining
I/flutter ( 6816): space in the vertical direction.
I/flutter ( 6816): These two directives are mutually exclusive. If a parent is to shrink-wrap its child, the child
I/flutter ( 6816): cannot simultaneously expand to fit its parent.
I/flutter ( 6816): Consider setting mainAxisSize to MainAxisSize.min and using FlexFit.loose fits for the flexible
I/flutter ( 6816): children (using Flexible rather than Expanded). This will allow the flexible children to size
I/flutter ( 6816): themselves to less than the infinite remaining space they would otherwise be forced to take, and
I/flutter ( 6816): then will cause the RenderFlex to shrink-wrap the children rather than expanding to fit the maximum
I/flutter ( 6816): constraints provided by the parent.
I/flutter ( 6816): The affected RenderFlex is:
I/flutter ( 6816): RenderFlex#9f534 relayoutBoundary=up11 NEEDS-LAYOUT NEEDS-PAINT
I/flutter ( 6816): The creator information is set to:
I/flutter ( 6816): Column ← _SingleChildViewport ← IgnorePointer-[GlobalKey#3670d] ← Semantics ← Listener ←
I/flutter ( 6816): _GestureSemantics ← RawGestureDetector-[LabeledGlobalKey<RawGestureDetectorState>#4878e] ←
I/flutter ( 6816): Listener ← _ScrollableScope ← _ScrollSemantics-[GlobalKey#c5885] ← RepaintBoundary ← CustomPaint ←
I/flutter ( 6816): ⋯
I/flutter ( 6816): The nearest ancestor providing an unbounded width constraint is:
I/flutter ( 6816): _RenderSingleChildViewport#155d8 relayoutBoundary=up10 NEEDS-LAYOUT NEEDS-PAINT
I/flutter ( 6816): creator: _SingleChildViewport ← IgnorePointer-[GlobalKey#3670d] ← Semantics ← Listener ←
I/flutter ( 6816): _GestureSemantics ← RawGestureDetector-[LabeledGlobalKey<RawGestureDetectorState>#4878e] ←
I/flutter ( 6816): Listener ← _ScrollableScope ← _ScrollSemantics-[GlobalKey#c5885] ← RepaintBoundary ← CustomPaint ←
I/flutter ( 6816): RepaintBoundary ← ⋯
I/flutter ( 6816): parentData: <none> (can use size)
I/flutter ( 6816): constraints: BoxConstraints(0.0<=w<=440.8, 0.0<=h<=649.3)
I/flutter ( 6816): size: MISSING
I/flutter ( 6816): See also: https://flutter.dev/layout/
I/flutter ( 6816): If this message did not help you determine the problem, consider using debugDumpRenderTree():
I/flutter ( 6816): https://flutter.dev/debugging/#rendering-layer
I/flutter ( 6816): http://docs.flutter.io/flutter/rendering/debugDumpRenderTree.html
I/flutter ( 6816): If none of the above helps enough to fix this problem, please don't hesitate to file a bug:
I/flutter ( 6816): https://github.com/flutter/flutter/issues/new?template=BUG.md
I/flutter ( 6816):
最佳答案
答案在于错误本身。当列位于可滚动 View 中时，该列将尝试收缩其内容，但是由于您使用Expanded作为该列的子级，因此它与试图收缩其子级的列相反。这是导致此错误的原因，因为这两个指令彼此完全相反。
如错误日志中所述，请尝试以下操作:
考虑将mainAxisSize设置为MainAxisSize.min(用于列)，并使用适合灵活的FlexFit.loose(使用Flexible而不是Expanded)。
关于flutter - 如何在SingleChildScrollView中使用Expanded？，我们在Stack Overflow上找到一个类似的问题：https://stackoverflow.com/questions/56326005/