计算乔达时间的月差

Question

在代码的第四行（忽略空格和注释）及之后，我正在计算两个日期之间的月份差异。这可行，但看起来有点老套。有更好的办法吗？

int handleAllowance(LocalDate today) {

    int allowance = membership.allowance();
    if (allowance == 0) return 0;

    // if update was last month (or earlier)
    int months = today.monthOfYear().getMaximumValue() - today.monthOfYear().getMinimumValue(); // yeah, 12, but just to be 100% correct :-)
    int curMonth = (today.getYear()               * months) + today.              getMonthOfYear();
    int updMonth = (lastAllowanceUpdate.getYear() * months) + lastAllowanceUpdate.getMonthOfYear();
    if (curMonth > updMonth) {

        // ...and if today is on or past update day
        int updateDay = Math.min(allowanceDay, today.dayOfMonth().getMaximumValue());
        if (today.getDayOfMonth() >= updateDay) {

            // number of months to give allowance (in the rare case this process fails to run for 2 months or more)
            int allowanceMonths = curMonth - updMonth;

            // give credits
            final int totalAllowance = allowance * allowanceMonths;
            giveCredits(totalAllowance);

            // update day
            lastAllowanceUpdate = lastAllowanceUpdate.plusMonths(allowanceMonths);

            // return the allowance given
            return totalAllowance;

        }

    }

    return 0;
}

Answer 1

Months.monthsBetween(
     start.withDayOfMonth(1),
     end.withDayOfMonth(1)).getMonths()

Answer 2

这与 Bozho 的解决方案非常相似：

  public static YearMonth toYearMonth(LocalDate localDate) {
    return new YearMonth(localDate.getYear(), localDate.getMonthOfYear());
  }

  public static int monthSwitches(LocalDate date1,LocalDate date2) {
    return Months.monthsBetween(toYearMonth(date1),toYearMonth(date2)).getMonths();
  }

Answer 3

这是我在评论 Bozho 时想到的解决方案

int handleAllowance(LocalDate today) {

    int allowance = membership.allowance();
    if (allowance == 0) return 0;

    // calculate month difference
    int allowanceMonths = Months.monthsBetween(lastAllowanceUpdate.withDayOfMonth(1), today.withDayOfMonth(1)).getMonths();

    // if update was last month or earlier
    if (allowanceMonths > 0) {

        // ...and if today is on or past update day
        int updateDay = Math.min(allowanceDay, today.dayOfMonth().getMaximumValue());
        if (today.getDayOfMonth() >= updateDay) {

            // give credits (multiply with months in the rare case this process consecutively fails to run for 2 months or more)
            final int totalAllowance = allowance * allowanceMonths;
            giveCredits(totalAllowance);

            // update day
            lastAllowanceUpdate = lastAllowanceUpdate.plusMonths(allowanceMonths);

            // return the allowance given
            return totalAllowance;

        }

    }

    return 0;
}