Constraints.hasBoundedWidth';:不为真 [英] 'constraints.hasBoundedWidth': is not true
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问题描述
以下是我的代码
main() => runApp(MyApp());
class MyApp extends StatelessWidget {
@override
Widget build(BuildContext context) {
return MaterialApp(
title: "Student Info",
debugShowCheckedModeBanner: false,
home: SafeArea(
child: HomePage(),
),
);
}
}
class HomePage extends StatelessWidget {
@override
Widget build(BuildContext context) {
return Scaffold(
backgroundColor: Colors.white,
body: ListView(
children: <Widget>[StudentScreenAppBar(), StudentGraduateList()],
),
);
}
}
class StudentScreenAppBar extends StatelessWidget {
@override
Widget build(BuildContext context) {
return Column(
mainAxisSize: MainAxisSize.min,
mainAxisAlignment: MainAxisAlignment.start,
children: <Widget>[
AppBar(
leading: IconButton(
icon: Icon(
Icons.arrow_back_ios,
color: Colors.black,
size: 20.0,
),
onPressed: () {}),
centerTitle: true,
title: Text(
"Student Info",
style: TextStyle(color: Colors.black),
),
actions: <Widget>[
IconButton(
icon: Icon(
Icons.settings,
size: 20.0,
color: Colors.black,
),
onPressed: () {}),
// SizedBox(width: 10.0,),
IconButton(
icon: Icon(
Icons.settings_ethernet,
color: Colors.black,
size: 20.0,
),
onPressed: () {})
],
elevation: 0.0,
backgroundColor: Colors.white,
),
Container(
decoration: BoxDecoration(border: Border.all(color: Colors.black)),
padding: const EdgeInsets.fromLTRB(8.0, 2.0, 8.0, 2.0),
child: Image.asset(
"images/isdi_school.png",
width: 40.0,
height: 15.0,
fit: BoxFit.contain,
))
],
);
}
}
class StudentGraduateList extends StatelessWidget {
@override
Widget build(BuildContext context) {
return Padding(
padding: const EdgeInsets.fromLTRB(0.0, 20.0, 0.0, 0.0),
child: Row(
mainAxisAlignment: MainAxisAlignment.spaceEvenly,
children: <Widget>[
yearListForUgPg("Under Graduate"),
yearListForUgPg("Post Graduate")
],
),
);
}
Widget yearListForUgPg(String graduationName) {
return Column(
children: <Widget>[
Container(
padding: const EdgeInsets.fromLTRB(25.0, 4.0, 25.0, 4.0),
child: Text(
graduationName,
style:
TextStyle(color: Colors.white, fontFamily: "suisseintlMedium"),
),
decoration: BoxDecoration(color: Colors.black),
),
ListView.builder(
shrinkWrap: true,
itemBuilder: (context, index) {
return Row(
mainAxisAlignment: MainAxisAlignment.center,
children: <Widget>[
Text(
"2018",
style: TextStyle(
fontFamily: "okomitoBold", color: Colors.black),
),
Icon(Icons.arrow_forward)
],
);
},
itemCount: 10,
)
],
);
}
}
ListView
小部件不会显示。如果我注释ListView
,则代码运行良好,并且我能够看到UI
。我尝试在扩展和灵活的Widget中包装ListView
,但不起作用。
如果我取消对ListView
的注释,则会收到错误,说'constraints.hasBoundedWidth'
:不是真的。我正试图在我的用户界面中实现这样的功能:
![图像][1]
推荐答案
只需将-Column
包装在Expanded
小部件中:这样您Column
将尝试占用父级Row
中的可用空间。
更新代码:
class StudentGraduateList extends StatelessWidget {
@override
Widget build(BuildContext context) {
return Padding(
padding: const EdgeInsets.fromLTRB(0.0, 20.0, 0.0, 0.0),
child: Row(
mainAxisAlignment: MainAxisAlignment.spaceEvenly,
children: <Widget>[
Expanded(child: yearListForUgPg("Under Graduate")),
Expanded(child: yearListForUgPg("Post Graduate"))
],
),
);
}
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