类型不是颤振类型错误的子类型

Question

class AddEvent extends MyCalendar {
AddEvent({super.key});
Map<DateTime, List<Event>> events = {
DateTime.utc(2022, 12, 10): [Event('1'), Event('2'), Event('3')],
DateTime.utc(2022, 12, 11): [Event('4')],
};
// ignore: unused_element
void _addCalendar() {
events[DateTime.now()] = Event('123') as List<Event>;
}
}
class Event {
String title;
Event(this.title);
}

你好!我现在心慌意乱我试图在我的应用程序日历事件添加功能我运行_addCalendar()通过点击按钮但不运行

输入图片描述

看我的代码…

Answer 1

我假设你试图在你的地图中添加Event到List<Event>，并且你不能像Event('123') as List<Event>这样用完全不同的类型转换类型，你需要做:

class AddEvent extends MyCalendar {
AddEvent({super.key});
Map<DateTime, List<Event>> events = {
DateTime.utc(2022, 12, 10): [Event('1'), Event('2'), Event('3')],
DateTime.utc(2022, 12, 11): [Event('4')],
};
// ignore: unused_element
void _addCalendar() {
final DateTime date = DateTime.now();
events[date] ??= [];
events[date] = events[date]!.add(Event('123'));
}
}
class Event {
String title;
Event(this.title);
}