如何使用 java8 设置工作日

Question

我有以下设置工作日的 Joda-Time 代码：

LocalDateTime localDateTime = new LocalDateTime(2016, 1, 1, 20,39);
LocalDateTime localDateTime1 = localDateTime.withDayOfWeek(7);

如何对 java.time 执行相同的操作？我看到没有 setDayOfTheWeek:

LocalDateTime time;
time.getDayOfWeek()

Answer 1

使用time.with(TemporalAdjuster), specifying an instance of DayOfWeek，例如

LocalDateTime time1 = time.with(DayOfWeek.FRIDAY);

Answer 2

您有几种方法可以做到：

LocalDateTime localDateTime = LocalDateTime.of(2016, 1, 1, 20, 39);

LocalDateTime ldt1 = localDateTime.with(ChronoField.DAY_OF_WEEK, 7);
LocalDateTime ldt2 = localDateTime.with(DayOfWeek.of(7));
//Or, more readable, as suggested by @AndyTurner
LocalDateTime ldt3 = localDateTime.with(DayOfWeek.SUNDAY);

Answer 3

它没有setDayOfTheWeek因为LocalDateTime是不可变的，所以它没有修改对象的setter。（乔达时间类也是不可变的！）。

在 Java 8:

中使用这个

LocalDateTime localDateTime = LocalDateTime.of(2016, 1, 1, 20,39);
LocalDateTime localDateTime1 = localDateTime.with(DayOfWeek.SUNDAY);

Answer 4

java.time API 没有 withDayOfWeek(DayOfWeek) 方法。但是它确实有一个通用的 with(TemporalAccessor) 方法可以代替使用：

LocalDateTime dt = base.with(DayOfWeek.WEDNESDAY);

但是，这留下了关于选择星期三的问题（它实际上在星期一到星期日的一周内更改了日期）。更好的方法是使用 TemporalAdjuster 使其更明确：

import static java.time.DayOfWeek.WEDNESDAY;
import static java.time.temporal.TemporalAdjusters.next;

LocalDateTime dt = base.with(next(WEDNESDAY));

这会将日期更改为基准日期之后的下一个星期三。请参阅 TemporalAdjusters 以了解可用的选项：

next(DayOfWeek)
nextOrSame(DayOfWeek)
previous(DayOfWeek)
previousOrSame(DayOfWeek)
firstInMonth(DayOfWeek)
lastInMonth(DayOfWeek)
dayOfWeekInMonth(int, DayOfWeek)

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