java JodaTime四舍五入到最近的一刻钟

Question

如果时间是10:36，我想把时间缩短到10:30。如果时间是1050，我想把时间四舍五入到10:45。等我不知道该怎么做。有什么想法吗

Answer 1

public static LocalTime roundDown(LocalTime time, int toMinuteInterval) {
    int slotNo = (int)(time.getMillisOfDay() / ((double)toMinuteInterval * 60 * 1000));
    int slotsPerHour = 60 / toMinuteInterval;
    int h = slotNo / slotsPerHour;
    int m = toMinuteInterval * (slotNo % slotsPerHour);
    return new LocalTime(h, m);
}

仅当toMinuteInterval是60倍（例如10、15、30等）时有效

Answer 2

谢谢你的回复。决定走这条路，不介绍JodaTime。在这个答案中How to round time to the nearest quarter hour in java?

    long timeMs = System.currentTimeMillis();       
    long roundedtimeMs = Math.round( (double)( (double)timeMs/(double)(15*60*1000) ) ) * (15*60*1000);

    Date myDt = new Date(roundedtimeMs);

    Calendar calendar = Calendar.getInstance();
    calendar.setTime(myDt);

    if(calendar.before(new Date())) {
        calendar.add(Calendar.MINUTE, -15);
    }

    System.out.println(calendar.getTime());

Answer 3

这个怎么样

public static LocalTime roundToQuarterHour(LocalTime time) {
  int oldMinute = time.getMinuteOfHour();
  int newMinute = 15 * (int) Math.round(oldMinute / 15.0);
  return time.plusMinutes(newMinute - oldMinute);
}

（由于有一个withMinuteOfHour方法，它可能看起来有点过于复杂了，但请记住，我们可能会将其调整到60，而withMinuteOfHour(60)是无效的。）