如何解决如何查找从现在开始到特定工作日的最近的将来日期?
我有一个约会管理方案,其中有一个availableWeekDays
字段列表,该字段在工作日的工作日可以预订。例如,如果星期一有空,我在availableWeekDays列表中的值为1。
我使用DateTime
将currentDate存储在DateTime.now()
变量中。
我要做的是首先看一下今天的工作日是否与某人的availableWeekDay相匹配。如果是,则bookingDate有效,否则我必须与人的工作日一起寻找最近的将来日期。我尝试了以下解决方案,但由于我正在使用第一个索引,因此它可以工作一周。
void main() {
DateTime bookingDate = DateTime.now();
int availableWeekDays = [1,4,7];
getDate(){
if(bookingDate.weekday == availableWeekDays[0]){
print("Available on $bookingDate ");
} else {
bookingDate = bookingDate.add(Duration(days: 1));
getDate();
}
}
getDate();
}
我想找到列表中所有工作日中最接近的将来日期。
解决方法
更有效的解决方案是:
DateTime getDate() {
var currentDay = bookingDate.weekday;
var offset = (availableWeekDay - currentDay).remainder(7);
return offset == 0 ? bookingDate : bookingDate.add(Duration(days: offset));
}
请注意,如果bookingDate
的时间接近午夜,则在日期上添加“天”(24小时的整数倍)可能会遇到夏令时问题。
DateTime findNearestWeekday(List<int> availableWeekdays) {
assert(availableWeekdays.isNotEmpty);
var date = DateTime.now();
final weekday = date.weekday;
for (var num in availableWeekdays) {
if (num == date.weekday) {
return date;
} else if (date.weekday < num) {
return date.add(Duration(days: num - weekday));
}
}
/// I have assumed that you will always have a sorted list of available
/// weekdays,in case you do not have a sorted list,either you can sort
/// the list first or just use this line (instead of the last one),///
/// ```dart
/// import 'dart:math'; /// Add on Top of file.
///
/// return date.add(Duration(days: 7 - weekday + availableWeekdays.reduce(min)))
/// ```
///
/// I will prefer to pre sort the array before storing it somewhere,/// because it will add an additional dependency dart:math
return date.add(Duration(days: 7 - weekday + availableWeekdays[0]));
}
,
我忘记了将结果重新分配给变量。现在可以使用。
void main() {
DateTime bookingDate = DateTime.now();
int availableWeekDay = 1;
getDate(){
if(bookingDate.weekday == availableWeekDay){
print("Available on $bookingDate ");
} else {
bookingDate = bookingDate.add(Duration(days: 1));
getDate();
}
}
getDate();
}