如何在java中将时间四舍五入到最近的四分之一小时? [英] How to round time to the nearest quarter hour in java?

问题描述

鉴于今天的时间，例如下午 2:24，我如何将它舍入到下午 2:30?

Given today's time e.g. 2:24PM, how do I get it to round to 2:30PM?

同样，如果时间是下午 2 点 17 分，我如何将它舍入到下午 2 点 15 分?

Similarly if the time was 2:17PM, how do I get it to round to 2:15PM?

推荐答案

四舍五入

您需要使用模数来截断一刻钟:

Rounding

You will need to use modulo to truncate the quarter hour:

Date whateverDateYouWant = new Date();
Calendar calendar = Calendar.getInstance();
calendar.setTime(whateverDateYouWant);

int unroundedMinutes = calendar.get(Calendar.MINUTE);
int mod = unroundedMinutes % 15;
calendar.add(Calendar.MINUTE, mod < 8 ? -mod : (15-mod));

正如EJP所指出的，这也可以(替换最后一行，仅当日历为宽松):

As pointed out by EJP, this is also OK (replacement for the last line, only valid if the calendar is lenient):

calendar.set(Calendar.MINUTE, unroundedMinutes + mod);

<小时>

改进

如果您想准确，您还必须截断较小的字段:

---

Improvements

If you want to be exact, you will also have to truncate the smaller fields:

calendar.set(Calendar.SECOND, 0);
calendar.set(Calendar.MILLISECOND, 0);

您也可以使用 DateUtils.truncate() 来自 Apache Commons/Langa> 这样做:

You can also use DateUtils.truncate() from Apache Commons / Lang to do this:

calendar = DateUtils.truncate(calendar, Calendar.MINUTE);

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