5行代碼無循環(huán)的解決方案

定義之間的天數(shù)的方式與ChronoUnit.DAYS.between(start, end)表示4星期一至星期五之間存在天數(shù)的方式相同。由于我們只對(duì)工作日感興趣，因此我們必須減去周末，因此從星期五到星期二會(huì)有2工作日（只需計(jì)算endDay - startDay并減去2周末）。1如果要包含結(jié)果，則添加到結(jié)果中，即不要間隔幾天。

我提出兩種解決方案。

第一個(gè)解決方案（5線，簡(jiǎn)短和隱秘）：

import java.time.*;

import java.time.temporal.*;

public static long calcWeekDays1(final LocalDate start, final LocalDate end) {

    final DayOfWeek startW = start.getDayOfWeek();

    final DayOfWeek endW = end.getDayOfWeek();

    final long days = ChronoUnit.DAYS.between(start, end);

    final long daysWithoutWeekends = days - 2 * ((days + startW.getValue())/7);

    //adjust for starting and ending on a Sunday:

    return daysWithoutWeekends + (startW == DayOfWeek.SUNDAY ? 1 : 0) + (endW == DayOfWeek.SUNDAY ? 1 : 0);

}

第二種解決方案：

public static long calcWeekDays2(final LocalDate start, final LocalDate end) {

    final int startW = start.getDayOfWeek().getValue();

    final int endW = end.getDayOfWeek().getValue();

    final long days = ChronoUnit.DAYS.between(start, end);

    long result = days - 2*(days/7); //remove weekends

    if (days % 7 != 0) { //deal with the rest days

        if (startW == 7) {

            result -= 1;

        } else if (endW == 7) {  //they can't both be Sunday, otherwise rest would be zero

            result -= 1;

        } else if (endW < startW) { //another weekend is included

            result -= 2;

        }

    }

    return result;

}