在JSR-310中查找下一个星期的一天 [英] Find next occurrence of a day-of-week in JSR-310

问题描述

给定一个JSR-310对象，例如 LocalDate ，我如何找到下个星期三（或任何其他星期几）的日期？

  LocalDate today = LocalDate.now（）; 
 LocalDate nextWed =？
  

解决方案

答案取决于您对下周三的定义; - ）

JSR-310使用 TemporalAdjusters class。

第一个选项是 next（）：

  LocalDate input = LocalDate 。现在（）; 
 LocalDate nextWed = input.with（TemporalAdjusters.next（DayOfWeek.WEDNESDAY））; 
  

第二个选项是 nextOrSame（）：

 LocalDate input = LocalDate.now（）; 
 LocalDate nextWed = input.with（TemporalAdjusters.nextOrSame（DayOfWeek.WEDNESDAY））; 
  

这两种不同取决于输入日期的星期几。

如果输入日期为2014-01-22（星期三），则：

• next（）将返回2014-01-29，一周后


• nextOrSame（）将返回2014-01-22，与输入相同

如果输入日期为2014-01-20（a星期一）然后：

• next（）将返回2014-01-22


• nextOrSame（）将返回2014-01-22

ie。 next（）总是返回一个更晚的日期，而 nextOrSame（）将返回输入日期，如果它匹配。 p>

请注意，两个选项看起来都比静态导入更好：

  LocalDate nextWed1 = input.with（next（WEDNESDAY））; 
 LocalDate nextWed2 = input.with（nextOrSame（WEDNESDAY））; 
  

TemporalAdjusters 还包括匹配的 previous（）和 previousOrSame（）方法。

Given a JSR-310 object, such as LocalDate, how can I find the date of next Wednesday (or any other day-of-week?

LocalDate today = LocalDate.now();
LocalDate nextWed = ???

解决方案

The answer depends on your definition of "next Wednesday" ;-)

JSR-310 provides two options using the TemporalAdjusters class.

The first option is next():

LocalDate input = LocalDate.now();
LocalDate nextWed = input.with(TemporalAdjusters.next(DayOfWeek.WEDNESDAY));

The second option is nextOrSame():

LocalDate input = LocalDate.now();
LocalDate nextWed = input.with(TemporalAdjusters.nextOrSame(DayOfWeek.WEDNESDAY));

The two differ depending on what day-of-week the input date is.

If the input date is 2014-01-22 (a Wednesday) then:

• next() will return 2014-01-29, one week later
• nextOrSame() will return 2014-01-22, the same as the input

If the input date is 2014-01-20 (a Monday) then:

• next() will return 2014-01-22
• nextOrSame() will return 2014-01-22

ie. next() always returns a later date, whereas nextOrSame() will return the input date if it matches.

Note that both options look much better with static imports:

LocalDate nextWed1 = input.with(next(WEDNESDAY));
LocalDate nextWed2 = input.with(nextOrSame(WEDNESDAY));

TemporalAdjusters also includes matching previous() and previousOrSame() methods.

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