使用Java 8分钟到天数 [英] Round minutes to ceiling using Java 8

问题描述

所以我很幸运地使用Java 8和新的时间APi，但是我没有看到任何四舍五入的功能...

基本上如果时间是...

  2014-08-28T10：01.00.000 ----> 2014-08-28T10：02.00.000 
 2014-08-28T10：01.10.123 ----> 2014-08-28T10：02.00.000 
 2014-08-28T10：01.25.123 ----> 2014-08-28T10：02.00.000 
 2014-08-28T10：01.49.123 ----> 2014-08-28T10：02.00.000 
 2014-08-28T10：01.59.999 ----> 2014-08-28T10：02.00.000 
  

这似乎没关系， / p>

  LocalDateTime now = LocalDateTime.now（Clock.systemUTC（））; 
 LocalDateTime newTime = now.plusMinutes（1）; 
 
 System.out.println（newTime.toString（））; 
 System.out.println（newTime.format（DateTimeFormatter.ofPattern（yyyy-dd-MM'T'HH：mm：00.000）））; 
  

解决方案

java.time API不支持四舍五入，但它支持四舍五入（截断），可以实现所需的行为（不完全是四舍五入）：

  LocalDateTime now = LocalDateTime.now（）; 
 LocalDateTime roundFloor = now.truncatedTo（ChronoUnit.MINUTES）; 
 LocalDateTime roundCeiling = now.truncatedTo（ChronoUnit.MINUTES）.plusMinutes（1）; 
  

此外，还有一个工具可以获得一分钟只能打勾一次的时钟，感兴趣的：

  Clock minuteTickingClock = Clock.tickMinutes（ZoneId.systemDefault（））; 
 LocalDateTime now = LocalDateTime.now（minuteTickingClock）; 
 LocalDateTime roundCeiling = now.plusMinutes（1）; 
  

此时钟将自动截断分钟到楼层（尽管是指定，以便可能会返回延迟的缓存值）。请注意，如果需要， Clock 可以存储在静态变量中。

最后，如果这是一个常见的操作您想在多个地方使用，可以编写一个库 TemporalAdjuster 功能执行舍入。 （调整器可以写一次，测试，并作为静态变量或方法使用）。

So I'm lucky enough to use Java 8 and the new time APi but I don't see any rounding functions...

Basically if the time is...

2014-08-28T10:01.00.000 ----> 2014-08-28T10:02.00.000
2014-08-28T10:01.10.123 ----> 2014-08-28T10:02.00.000
2014-08-28T10:01.25.123 ----> 2014-08-28T10:02.00.000
2014-08-28T10:01.49.123 ----> 2014-08-28T10:02.00.000
2014-08-28T10:01.59.999 ----> 2014-08-28T10:02.00.000

This seems to be ok, but is it right?

LocalDateTime now =  LocalDateTime.now(Clock.systemUTC());
LocalDateTime newTime =  now.plusMinutes(1);

System.out.println(newTime.toString());
System.out.println(newTime.format(DateTimeFormatter.ofPattern("yyyy-dd-MM'T'HH:mm:00.000")));

解决方案

The java.time API does not support rounding to ceiling, however it does support rounding to floor (truncation) which enables the desired behaviour (which isn't exactly rounding to ceiling):

LocalDateTime now =  LocalDateTime.now();
LocalDateTime roundFloor =  now.truncatedTo(ChronoUnit.MINUTES);
LocalDateTime roundCeiling =  now.truncatedTo(ChronoUnit.MINUTES).plusMinutes(1);

In addition, there is a facility to obtain a clock that only ticks once a minute, which may be of interest:

Clock minuteTickingClock = Clock.tickMinutes(ZoneId.systemDefault());
LocalDateTime now =  LocalDateTime.now(minuteTickingClock);
LocalDateTime roundCeiling =  now.plusMinutes(1);

This clock will automatically truncate minutes to floor (although it is specified such that it may return a delayed cached value). Note that a Clock may be stored in a static variable if desired.

Finally, if this is a common operation that you want to use in multiple places, it is possible to write a library TemporalAdjuster function to perform the rounding. (Adjusters can be written once, tested, and made available as a static variable or method).

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