getWeekday static method
获取周几
Implementation
static String? getWeekday(DateTime? dateTime) {
if (dateTime == null) return null;
String weekday = switch (dateTime.weekday) {
1 => '星期一',
2 => '星期二',
3 => '星期三',
4 => '星期四',
5 => '星期五',
6 => '星期六',
7 => '星期日',
_ => '',
};
return weekday;
}