如何在 Java 8 中为 LocalDate 添加天数时跳过周末？
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How to skip weekends while adding days to LocalDate in Java 8?
提问by Anmol Gupta
Other answers here refer to Joda API.
I want to do it using java.time.
此处的其他答案参考 Joda API。我想使用java.time.
Suppose today's date is 26th Nov 2015-Thursday, when I add 2 business days to it, I want the result as Monday 30th Nov 2015.
假设今天的日期是 2015 年 11 月 26 日-星期四，当我添加 2 个工作日时，我希望结果为 2015 年 11 月 30 日星期一。
I am working on my own implementation but it would be great if something already exists!
我正在研究我自己的实现，但如果已经存在的话，那就太好了！
EDIT:
编辑：
Is there a way to do it apart from looping over?
除了循环之外，有没有办法做到这一点？
I was trying to derive a function like:
我试图推导出一个函数，如：
Y = f(X1,X2) where
Y is actual number of days to add,
X1 is number of business days to add,
X2 is day of the week (1-Monday to 7-Sunday)
Then given X1and X2(derived from day of week of the date), we can find Yand then use plusDays()method of LocalDate.
然后给出X1和X2（从日期的星期几导出），我们可以找到Y然后使用 的plusDays()方法LocalDate。
I have not been able to derive it so far, its not consistent. Can anyone confirm that looping over until desired number of workdays are added is the only way?
到目前为止我还无法得出它，它不一致。任何人都可以确认循环直到添加所需的工作日数是唯一的方法吗？
采纳答案by Modus Tollens
The following method adds days one by one, skipping weekends, for positive values of workdays:
以下方法为 的正值逐天添加天数，跳过周末workdays：
public LocalDate add(LocalDate date, int workdays) {
if (workdays < 1) {
return date;
}
LocalDate result = date;
int addedDays = 0;
while (addedDays < workdays) {
result = result.plusDays(1);
if (!(result.getDayOfWeek() == DayOfWeek.SATURDAY ||
result.getDayOfWeek() == DayOfWeek.SUNDAY)) {
++addedDays;
}
}
return result;
}
After some fiddling around, I came up with an algorithm to calculatethe number of workdays to add or subtract.
经过一番摆弄之后，我想出了一个算法来计算要增加或减少的工作日数。
/**
* @param dayOfWeek
* The day of week of the start day. The values are numbered
* following the ISO-8601 standard, from 1 (Monday) to 7
* (Sunday).
* @param businessDays
* The number of business days to count from the day of week. A
* negative number will count days in the past.
*
* @return The absolute (positive) number of days including weekends.
*/
public long getAllDays(int dayOfWeek, long businessDays) {
long result = 0;
if (businessDays != 0) {
boolean isStartOnWorkday = dayOfWeek < 6;
long absBusinessDays = Math.abs(businessDays);
if (isStartOnWorkday) {
// if negative businessDays: count backwards by shifting weekday
int shiftedWorkday = businessDays > 0 ? dayOfWeek : 6 - dayOfWeek;
result = absBusinessDays + (absBusinessDays + shiftedWorkday - 1) / 5 * 2;
} else { // start on weekend
// if negative businessDays: count backwards by shifting weekday
int shiftedWeekend = businessDays > 0 ? dayOfWeek : 13 - dayOfWeek;
result = absBusinessDays + (absBusinessDays - 1) / 5 * 2 + (7 - shiftedWeekend);
}
}
return result;
}
Usage Example:
用法示例：
LocalDate startDate = LocalDate.of(2015, 11, 26);
int businessDays = 2;
LocalDate endDate = startDate.plusDays(getAllDays(startDate.getDayOfWeek().getValue(), businessDays));
System.out.println(startDate + (businessDays > 0 ? " plus " : " minus ") + Math.abs(businessDays)
+ " business days: " + endDate);
businessDays = -6;
endDate = startDate.minusDays(getAllDays(startDate.getDayOfWeek().getValue(), businessDays));
System.out.println(startDate + (businessDays > 0 ? " plus " : " minus ") + Math.abs(businessDays)
+ " business days: " + endDate);
Example Output:
示例输出：
2015-11-26 plus 2 business days: 2015-11-30
2015-11-26 minus 6 business days: 2015-11-18
2015-11-26 加 2 个工作日：2015-11-30
2015-11-26减6个工作日：2015-11-18
回答by JodaStephen
Determining business days is fundamentally a question of looping over dates, checking if each is a weekend or holiday.
确定工作日基本上是一个循环日期的问题，检查每个日期是周末还是假期。
The Strataproject from OpenGamma (I am a committer) has an implementation of a holiday calendar. The APIcovers the case of finding the date 2 business days later. The implementation has an optimized bitmap designthat performs better than day by day looping. It may be of interest here.
OpenGamma的Strata项目（我是提交者）有一个假期日历的实现。该API包括发现之日起2个工作日之后的情况。该实现具有优化的位图设计，其性能优于逐日循环。这里可能很有趣。
回答by assylias
Here is a version which supports both positive and negative number of days and exposes the operation as a TemporalAdjuster. That allows you to write:
这是一个支持正数和负数天数并将操作公开为TemporalAdjuster. 这允许你写：
LocalDate datePlus2WorkingDays = date.with(addWorkingDays(2));
Code:
代码：
/**
* Returns the working day adjuster, which adjusts the date to the n-th following
* working day (i.e. excluding Saturdays and Sundays).
* <p>
* If the argument is 0, the same date is returned if it is a working day otherwise the
* next working day is returned.
*
* @param workingDays the number of working days to add to the date, may be negative
*
* @return the working day adjuster, not null
*/
public static TemporalAdjuster addWorkingDays(long workingDays) {
return TemporalAdjusters.ofDateAdjuster(d -> addWorkingDays(d, workingDays));
}
private static LocalDate addWorkingDays(LocalDate startingDate, long workingDays) {
if (workingDays == 0) return nextOrSameWorkingDay(startingDate);
LocalDate result = startingDate;
int step = Long.signum(workingDays); //are we going forward or backward?
for (long i = 0; i < Math.abs(workingDays); i++) {
result = nextWorkingDay(result, step);
}
return result;
}
private static LocalDate nextOrSameWorkingDay(LocalDate date) {
return isWeekEnd(date) ? nextWorkingDay(date, 1) : date;
}
private static LocalDate nextWorkingDay(LocalDate date, int step) {
do {
date = date.plusDays(step);
} while (isWeekEnd(date));
return date;
}
private static boolean isWeekEnd(LocalDate date) {
DayOfWeek dow = date.getDayOfWeek();
return dow == SATURDAY || dow == SUNDAY;
}
回答by Ralph
This is a method which is adding or subtracting workdays to a given calendar object:
这是一种向给定日历对象添加或减去工作日的方法：
/**
* This method adds workdays (MONDAY - FRIDAY) to a given calendar object.
* If the number of days is negative than this method subtracts the working
* days from the calendar object.
*
*
* @param cal
* @param days
* @return new calendar instance
*/
public static Calendar addWorkDays(final Calendar baseDate, final int days) {
Calendar resultDate = null;
Calendar workCal = Calendar.getInstance();
workCal.setTime(baseDate.getTime());
int currentWorkDay = workCal.get(Calendar.DAY_OF_WEEK);
// test if SATURDAY ?
if (currentWorkDay == Calendar.SATURDAY) {
// move to next FRIDAY
workCal.add(Calendar.DAY_OF_MONTH, (days < 0 ? -1 : +2));
currentWorkDay = workCal.get(Calendar.DAY_OF_WEEK);
}
// test if SUNDAY ?
if (currentWorkDay == Calendar.SUNDAY) {
// move to next FRIDAY
workCal.add(Calendar.DAY_OF_MONTH, (days < 0 ? -2 : +1));
currentWorkDay = workCal.get(Calendar.DAY_OF_WEEK);
}
// test if we are in a working week (should be so!)
if (currentWorkDay >= Calendar.MONDAY && currentWorkDay <= Calendar.FRIDAY) {
boolean inCurrentWeek = false;
if (days > 0)
inCurrentWeek = (currentWorkDay + days < 7);
else
inCurrentWeek = (currentWorkDay + days > 1);
if (inCurrentWeek) {
workCal.add(Calendar.DAY_OF_MONTH, days);
resultDate = workCal;
} else {
int totalDays = 0;
int daysInCurrentWeek = 0;
// fill up current week.
if (days > 0) {
daysInCurrentWeek = Calendar.SATURDAY - currentWorkDay;
totalDays = daysInCurrentWeek + 2;
} else {
daysInCurrentWeek = -(currentWorkDay - Calendar.SUNDAY);
totalDays = daysInCurrentWeek - 2;
}
int restTotalDays = days - daysInCurrentWeek;
// next working week... add 2 days for each week.
int x = restTotalDays / 5;
totalDays += restTotalDays + (x * 2);
workCal.add(Calendar.DAY_OF_MONTH, totalDays);
resultDate = workCal;
}
}
return resultDate;
}
回答by Franchoo
This is a way to add business days using java.time Classes, some functional interfaces & lambda...
这是一种使用 java.time 类、一些功能接口和 lambda 添加工作日的方法...
IntFunction<TemporalAdjuster> addBusinessDays = days -> TemporalAdjusters.ofDateAdjuster(
date -> {
LocalDate baseDate =
days > 0 ? date.with(TemporalAdjusters.previousOrSame(DayOfWeek.MONDAY))
: days < 0 ? date.with(TemporalAdjusters.nextOrSame(DayOfWeek.FRIDAY)) : date;
int businessDays = days + Math.min(Math.max(baseDate.until(date).getDays(), -4), 4);
return baseDate.plusWeeks(businessDays / 5).plusDays(businessDays % 5);
});
LocalDate.of(2018, 1, 5).with(addBusinessDays.apply(2));
//Friday Jan 5, 2018 -> Tuesday Jan 9, 2018
LocalDate.of(2018, 1, 6).with(addBusinessDays.apply(15));
//Saturday Jan 6, 2018 -> Friday Jan 26, 2018
LocalDate.of(2018, 1, 7).with(addBusinessDays.apply(-10));
//Sunday Jan 7, 2018 -> Monday Dec 25, 2017
Supports negative values and from any week day!
支持负值和任何工作日！
回答by Q10Viking
Example:
例子：
Calculate the total number of days from the date I started working except Saturday and Sunday.
计算从我开始工作之日起除周六和周日外的总天数。
public class App {
public static void main(String[] args) throws Exception {
/** I write the code when 2019-8-15 */
LocalDate now = LocalDate.now();
LocalDate startWork = LocalDate.parse("2019-06-17");
/** get all days */
long allDays = Duration.between(startWork.atStartOfDay(), now.atStartOfDay()).toDays() + 1;
System.out.println("This is the " + allDays + "th day you enter the company.");
/** variable to store day except sunday and saturday */
long workDays = allDays;
for (int i = 0; i < allDays; i++) {
if (startWork.getDayOfWeek() == DayOfWeek.SATURDAY || startWork.getDayOfWeek() == DayOfWeek.SUNDAY) {
workDays--;
}
startWork = startWork.plusDays(1);
}
System.out.println("You actually work for a total of " + workDays + " days.");
}
}
/**
This is the 60th day you enter the company.
You actually work for a total of 44 days.
*/
- Hope that can help you.
- 希望能帮到你。
