我在 StatelessWidget 中有一个 ListView 。它有项目,每个项目都包含一个复选框。当有人检查某个项目时,我希望 ListView 将其作为参数发送到另一个页面。但是当我这样做时,它给了我这个错误:
I/flutter ( 7067): The following UnsupportedError was thrown while handling a gesture:
I/flutter ( 7067): Unsupported operation: Cannot add to an unmodifiable list
I/flutter ( 7067): When the exception was thrown, this was the stack:
这是我的代码
class StudentsList extends StatelessWidget {
final List<Child> mList;
StudentsList({this.mList});
@override
Widget build(BuildContext context) {
List<Child> selectedList = [];
return Container(
margin: EdgeInsets.only(top: 50, bottom: 20),
child: ListView.builder(
shrinkWrap: true,
physics: ClampingScrollPhysics(),
itemCount: mList == null ? 0 : mList.length,
padding: EdgeInsets.only(right: 10),
itemBuilder: (BuildContext context, int position) {
return GestureDetector(
onTap: () {
if (selectedList.isEmpty) {
Navigator.push(
context,
new MaterialPageRoute(
builder: (BuildContext context) => SolokPage(
mChildList: [mList[position]],
isTeacher: true,
),
),
);
} else {
if (!selectedList.contains(mList[position])) {
selectedList.add(mList[position]);
}
Navigator.push(
context,
new MaterialPageRoute(
builder: (BuildContext context) => SolokPage(
mChildList: selectedList,
isTeacher: true,
),
),
);
}
},
child: StudentItem(
student: mList[position],
),
);
},
),
);
}
}