Dart 颤振-通用功能类型定义错误
在教程之后,我将在Flatter中编写一个基本loadmore listview:Dart 颤振-通用功能类型定义错误,dart,flutter,Dart,Flutter,在教程之后,我将在Flatter中编写一个基本loadmore listview: 将typedef函数定义为listview适配器,它会为每个项目返回一个小部件: typedef Widget WidgetAdapter<T>(T t); 如何修复它。请帮帮我。非常感谢。您的StatefullWidget类中的createState()方法有问题 像这样更新createState()方法 @override State createState() => new _
- 将typedef函数定义为listview适配器,它会为每个项目返回一个小部件:
typedef Widget WidgetAdapter<T>(T t);
如何修复它。请帮帮我。非常感谢。您的StatefullWidget类中的createState()方法有问题 像这样更新createState()方法
@override
State createState() => new _LoadingListViewState<T>()
@覆盖
State createState()=>新建_LoadingListViewState()
将您的createState方法更改为@覆盖状态createState()=>新建\u LoadingListviewState()
?
class _LoadingListViewState<T> extends State<LoadingListView<T>> {
...
List<T> objects = [];
...
Widget itemBuilder(BuildContext context, int index) {
return widget.widgetAdapter != null ? widget.widgetAdapter(objects[index]);
: new Container();
}
}
@override
Widget build(BuildContext context) {
Widget w;
w = new LoadingListView<User>(
request, widgetAdapter: adapt, pageSize: widget.pageSize, pageThreshold: widget.pageThreshold);
return w;
}
Widget adapt(User user){
return new UserItem(user); //return widget UserItem
}
type '(User) => Widget' is not a subtype of type '(dynamic) => Widget'
@override
State createState() => new _LoadingListViewState<T>()