如何找到任意日期的最近工作日? [英] How to find nearest week day for an arbitrary date?

问题描述

是否有一种优雅的方法可以使用JodaTime查找给定日期的星期几?我最初以为是setCopy()，但这将日期设置为同一周中的特定日期 .因此，如果ld是2011-11-27并且day是星期一"，则下面的函数将返回2011-11-21，而不是我想要的2011-11-28.

Is there an elegant way to find the nearest day of the week for a given date using JodaTime? I initially thought setCopy() would be it, but this sets the day to the particular day in the same week. Thus, if ld is 2011-11-27 and day is "Monday" the following function returns 2011-11-21, and not 2011-11-28 as I want.

    // Note that "day" can be _any_ day of the week, not just weekdays.
    LocalDate getNearestDayOfWeek(LocalDate ld, String day) {
        return ld.dayOfWeek().setCopy(day);
    }

各种输入所需的输出:

2011-12-04, Monday    => 2011-12-05
2011-12-04, Tuesday   => 2011-12-06
2011-12-04, Wednesday => 2011-12-07
2011-12-04, Thursday  => 2011-12-01
2011-12-04, Friday    => 2011-12-02
2011-12-04, Saturday  => 2011-12-03
2011-12-04, Sunday    => 2011-12-04

2011-12-05, Monday    => 2011-12-05
2011-12-05, Tuesday   => 2011-12-06
2011-12-05, Wednesday => 2011-12-07
2011-12-05, Thursday  => 2011-12-08
2011-12-05, Friday    => 2011-12-02
2011-12-05, Saturday  => 2011-12-03
2011-12-05, Sunday    => 2011-12-04

下面是我想出的一种变通方法，该方法可解决当前情况下的特定限制，但是我很乐意寻求帮助，以找到始终有效的完全通用的解决方案.

Below is a work-around I came up with that works for the particular constraints in my current situation, but I'd love to get help find a completely generic solution that works always.

    LocalDate getNearestDayOfWeek(LocalDate ld, String day) {
        LocalDate target = ld.dayOfWeek().setCopy(day);
        if (ld.getDayOfWeek() > DateTimeConstants.SATURDAY) {
            target = target.plusWeeks(1);
        }
        return target;
    }

推荐答案

在Jodatime中，这种事情应该可以执行三到四行:

In Jodatime, this kind of thing should be doable with three or four lines:

   /** Given a reference LocalDate and a day of week, eg DateTimeConstants.MONDAY 
       Returns the nearest date with that day of week */
   public static LocalDate getNearestDayOfWeek(LocalDate t0,int dow) {
        LocalDate t1 = t0.withDayOfWeek(dow);
        LocalDate t2 = t1.isBefore(t0) ? t1.plusWeeks(1) : t1.minusWeeks(1);
        return  Math.abs(Days.daysBetween(t1, t0).getDays()) < 
                Math.abs(Days.daysBetween(t2, t0).getDays()) ? t1 : t2;
   }

或更紧凑，更高效:

public static LocalDate getNearestDayOfWeek(LocalDate t0, int dow) {
    LocalDate t1 = t0.withDayOfWeek(dow);
    if (t1.isBefore(t0.minusDays(3)))       return t1.plusWeeks(1);
    else if (t1.isAfter(t0.plusDays(3)))    return t1.minusWeeks(1);
    else return t1;
}

如果您想将星期几作为String传递:

And if you want to pass the day-of-the-week as String:

public static LocalDate getNearestDayOfWeek(LocalDate t0, String dow) {
    return getNearestDayOfWeek(t0,t0.dayOfWeek().setCopy(dow).getDayOfWeek());
}

示例:

    // prints 2011-11-28
   public static  void  main(String[] args) throws Exception {
        LocalDate today = new LocalDate(2011,11,27);
        int dow = DateTimeConstants.MONDAY;
        System.out.println(getNearestDayOfWeek(today ,dow ));
   }

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