JodaTime四舍五入到最接近的一刻钟

Question

如果时间是10:36，我想把时间缩短到10:30。如果时间是1050我想把时间缩短到10:45。等...我不知道该怎么做。有什么想法吗？

Answer 1

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);
}

（可能看起来有点过于复杂，因为有withMinuteOfHour方法，但请记住，我们可能会舍入到60，withMinuteOfHour(60)无效。）

Answer 2

感谢您的回复。决定走这条路而不介绍JodaTime。如答案How to round time to the nearest quarter hour in java?

中所示

    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

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是因子60（例如10,15,30等）时才有效。