How to round time to the nearest quarter hour in java?

Question

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

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

Answer 1

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));

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);

---

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);

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

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

Answer 2

If you just want to round down this is a more readable version using Java Time API:

LocalDateTime time = LocalDateTime.now();
LocalDateTime lastQuarter = time.truncatedTo(ChronoUnit.HOURS)
                                .plusMinutes(15 * (time.getMinute() / 15));

output:

2016-11-04T10:58:10.228

2016-11-04T10:45:00

Answer 3

A commented implementation for Java 8. Accepts arbitrary rounding units and increments:

 public static ZonedDateTime round(ZonedDateTime input, TemporalField roundTo, int roundIncrement) {
    /* Extract the field being rounded. */
    int field = input.get(roundTo);

    /* Distance from previous floor. */
    int r = field % roundIncrement;

    /* Find floor and ceiling. Truncate values to base unit of field. */
    ZonedDateTime ceiling = 
        input.plus(roundIncrement - r, roundTo.getBaseUnit())
        .truncatedTo(roundTo.getBaseUnit());

    ZonedDateTime floor = 
        input.plus(-r, roundTo.getBaseUnit())
        .truncatedTo(roundTo.getBaseUnit());

    /*
     * Do a half-up rounding.
     * 
     * If (input - floor) < (ceiling - input) 
     * (i.e. floor is closer to input than ceiling)
     *  then return floor, otherwise return ceiling.
     */
    return Duration.between(floor, input).compareTo(Duration.between(input, ceiling)) < 0 ? floor : ceiling;
  }

Source: myself

Answer 4

With the answer above you end up with all kind of interesting code to handle overflows to hours, days etc.

I would use the time in ms since the epoch.

add 7.5minutes or 7.5x60x1000 = 450000

and truncate to a multiple of 900000

new Date(900000 * ((date.getTime() + 450000) / 900000))

This works, because the time where the ms time starts happens to be 00:00:00. And since all time zones in the world change in 15min steps, this does not affect rounding to quarters.

(Oops, I had a 0 too much and forgot some important parentheses : it is still too early)

Answer 5

It's simple, find the number of quaters since 1970 as double, round it and multiply by 15 minutes:

long timeMs = System.System.currentTimeMillis();

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

Set your Date or Calendar object with that. Change the time you want mutiple by "n"

Answer 6

Wonderful post, thank you so much guys! It was exactly what I needed :)

Here's my code based on jour work.

My usecase is "Given it's 11:47 am, I want to set two dates symbolizing the current 5-minutes frame : 11:45 am and 11:50 am"

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

            int modulo = calendar.get(Calendar.MINUTE) % 5;
            if(modulo > 0) {

                calendar.add(Calendar.MINUTE, -modulo);
            }

            myObject.setStartDate(calendar.getTime());

            calendar.add(Calendar.MINUTE, 5);
            myObject.setDueDate(calendar.getTime()); 

Answer 7

You can use this simple code...

int mode = min % 15;
if (mode > 15 / 2) {
    min = 15 - mode;
} else {
    min = 0 - mode;
}
cal.add(Calendar.MINUTE, min);

Answer 8

One more alternate approach using java Instant api.

Instant instant =  Instant.now();
int intervalInMinutes = 10;
instant.truncatedTo(ChronoUnit.MINUTES).minus(instant.atZone(ZoneId.of("UTC")).getMinute() % (1* intervalInMinutes),ChronoUnit.MINUTES);

Answer 9

If you need to round down time to the nearest arbitrary level provided as Duration:

static long truncateTo(long timeEpochMillis, Duration d) {
    long x = timeEpochMillis / d.toMillis();
    return x * d.toMillis();
}

Answer 10

java.time

I recommend you do it using the the modern date-time API^*:

import java.time.LocalDate;
import java.time.LocalTime;
import java.time.ZoneId;
import java.time.ZonedDateTime;
import java.time.temporal.ChronoUnit;
import java.util.stream.Stream;

public class Main {
    public static void main(String[] args) {
        
        // Change it to the applicable ZoneId e.g. ZoneId.of("Asia/Kolkata")
        ZoneId zoneId = ZoneId.systemDefault();
        
        Stream.of(
                        "10:00", 
                        "10:05", 
                        "10:10", 
                        "10:15", 
                        "10:20", 
                        "10:25", 
                        "10:30"
            ).forEach(t -> System.out.println(roundToNearestQuarter(t, zoneId)));
    }

    static ZonedDateTime roundToNearestQuarter(String strTime, ZoneId zoneId) {
        LocalTime time = LocalTime.parse(strTime);
        return LocalDate.now()
                        .atTime(time)
                        .atZone(zoneId)
                        .truncatedTo(ChronoUnit.HOURS)
                        .plusMinutes(15 * Math.round(time.getMinute() / 15.0));
    }
}

Output:

2021-04-02T10:00+01:00[Europe/London]
2021-04-02T10:00+01:00[Europe/London]
2021-04-02T10:15+01:00[Europe/London]
2021-04-02T10:15+01:00[Europe/London]
2021-04-02T10:15+01:00[Europe/London]
2021-04-02T10:30+01:00[Europe/London]
2021-04-02T10:30+01:00[Europe/London]

In case you are looking for just time, use ZonedDateTime#toLocalTime to get the LocalTime from the obtained ZonedDateTime.

Learn more about the modern date-time API from Trail: Date Time.

---

^{* The java.util date-time API and their formatting API, SimpleDateFormat are outdated and error-prone. It is recommended to stop using them completely and switch to the modern date-time API. For any reason, if you have to stick to Java 6 or Java 7, you can use ThreeTen-Backport which backports most of the java.time functionality to Java 6 & 7. If you are working for an Android project and your Android API level is still not compliant with Java-8, check Java 8+ APIs available through desugaring and How to use ThreeTenABP in Android Project.}

Answer 11

Maybe you can use an utility library for manipulating Dates, here for example you have a round method which can be useful for you:

http://commons.apache.org/lang/api-2.4/org/apache/commons/lang/time/DateUtils.html#round%28java.util.Calendar,%20int%29

Here an example in code:

    FastDateFormat formatter = DateFormatUtils.ISO_DATETIME_TIME_ZONE_FORMAT;

    Date now = new Date();
    System.out.println("now = " + formatter.format(now));       

    // Get nearest second
    Date nearestSecond = DateUtils.round(now, Calendar.SECOND);
    System.out.println("nearestSecond = " + formatter.format(nearestSecond));

    // Get nearest minute
    Date nearestMinute = DateUtils.round(now, Calendar.MINUTE);
    System.out.println("nearestMinute = " + formatter.format(nearestMinute));

    // Get nearest hour
    Date nearestHour   = DateUtils.round(now, Calendar.HOUR);
    System.out.println("nearestHour = " + formatter.format(nearestHour));

Answer 12

public static Date getCurrentDateTimeWithQuarterRounding() {
    final Calendar calendar = new GregorianCalendar();
    calendar.setTime(new Date());
    calendar.set(Calendar.MILLISECOND, 0);
    calendar.set(Calendar.SECOND, 0);
    final int minutes = calendar.get(Calendar.MINUTE);

    if (minutes < 15) {
        calendar.set(Calendar.MINUTE, 0);
    } else if (minutes >= 45) {
        calendar.set(Calendar.MINUTE, 45);
    } else if (minutes < 30) {
        calendar.set(Calendar.MINUTE, 15);
    } else {
        calendar.set(Calendar.MINUTE, 30);
    }

    return calendar.getTime();
}

Answer 13

minutes = (int) (Math.round(minutes / 15.0) * 15.0);

Answer 14

if you have the minutes you can round them with the following function:
int minutes = i % 15 < 8 ? i / 15 * 15 : (i / 15 + 1) * 15;

Answer 15

Using some code on I found on Stackoverflow, I have created the following code. It will output for every minute the quarter it will be rounded to.

import java.time.LocalDateTime;
import java.time.format.DateTimeFormatter;

DateTimeFormatter Datum_Format = DateTimeFormatter.ofPattern("HH:mm");

LocalDateTime time = LocalDateTime.now();
for(int i=0; i<=59; i++) {
  time = time.withMinute(i);
  int Minute = time.getMinute();
  int Quarter = 15 * (int) Math.round(Minute / 15);
  if (Quarter == 60) { 
    Time2 = time.plusHours(1);
    Time2 = Time2.withMinute(0); 
    LOG.info (Datum_Format.format(time) + "," + Datum_Format.format(Time2));
  }
  else {
    Time2 = time; 
    Time2 = Time2.withMinute(Quarter); 
    LOG.info (Datum_Format.format(time) + "," + Datum_Format.format(Time2));
  }
}

As I output the code to a console, you will have to replace the LOG.info with something like System.out.println.

Result:

2016-08-16 15:14:31 INFO 15:05,15:00
2016-08-16 15:14:31 INFO 15:06,15:00
2016-08-16 15:14:31 INFO 15:07,15:00
2016-08-16 15:14:31 INFO 15:08,15:15
2016-08-16 15:14:31 INFO 15:09,15:15
2016-08-16 15:14:31 INFO 15:10,15:15

Answer 16

Use the following functions to get the minutes rounded to last quarter getRecentQuater():Date, getSysDate_LastQuarterMins("dd.MM.yyyy HH:mm:ss"):String: ^{Converting LocalDateTime to Date}

public static Date getRecentQuater() {
    LocalDateTime time = LocalDateTime.now();
    LocalDateTime lastQuarter = time.truncatedTo(ChronoUnit.HOURS).plusMinutes(getLastQuarterValue(time.getMinute()));
    System.out.println("lastQuarter LocalDateTime: " + lastQuarter);

    Date date = Date.from(lastQuarter.atZone(ZoneId.systemDefault()).toInstant());
    System.out.println("lastQuarter Date: " + lastQuarter);
    return date;
}
public static String getSysDate_LastQuarterMins(String dateFormat) {
    Date date = getRecentQuater();
    SimpleDateFormat ft = new SimpleDateFormat (dateFormat);
    String sysDate_RoundMin = ft.format(date);
    System.out.println("getSysDate_LastQuarterMins() LocalDateTime : "+sysDate_RoundMin);
    return sysDate_RoundMin;
}

getSysDate_LastQuarterMins() : Mon Jan 20 17:30:00 CET 2020

public static Date getSysDate_LastQuarterMins() {
    Calendar cal = Calendar.getInstance();
    cal.setTime( new Date(System.currentTimeMillis()) );

    int min = cal.get(Calendar.MINUTE);

    cal.set(Calendar.MINUTE, getLastQuarterValue(min));
    cal.set(Calendar.SECOND, 00);
    Date lastQuarter = cal.getTime();
    System.out.println("getSysDate_LastQuarterMins() Calendar : "+lastQuarter);
    return lastQuarter;
}

You can find the LastQuarter Value Round value from the follwing fucntions, provided with some outputs on function call diaplayLastQuarter_RoundValue(min):

Min: 10, LastQuarter:  0, Round: 15
Min: 24, LastQuarter: 15, Round: 30
Min: 36, LastQuarter: 30, Round: 30
Min: 37, LastQuarter: 30, Round: 30
Min: 38, LastQuarter: 30, Round: 45
Min: 39, LastQuarter: 30, Round: 45
Min: 44, LastQuarter: 30, Round: 45
Min: 57, LastQuarter: 45, Round: 00 [57, 07:45:00, 08:00:00]

public static void diaplayLastQuarter_RoundValue(int minutes) {
    System.out.format("Min: %2d, LastQuarter: %2d, Round: %2d\n",
            minutes, getLastQuarterValue(minutes), getRoundValue(minutes));
}
public static int getLastQuarterValue(int minutes) {
    int min = 15 * (minutes / 15);
    //System.out.println("Min: "+minutes+", getLastQuarterValue : "+ min);
    return min;
}
public static int getRoundValue(int minutes) {
    getLastQuarterValue(minutes);
    int minRound = (int) (Math.round(minutes / 15.0) * 15.0);
    //System.out.println("Min: "+minutes+", getRoundValue : "+minRound);
    return minRound;
}

Answer 17

If someone is interested to get the nearest (up or down) five or fifteen interval, I made a function using module that does the job.

public LocalTime roundToTheNearestInterval(LocalTime original, Integer measurementInterval) {
        LocalTime nearest;
        int mod;
        switch (measurementInterval) {
            case 5:
                mod = original.getMinute() % 5;
                nearest = mod >= 3 ?
                        original.truncatedTo(ChronoUnit.HOURS)
                                .plusMinutes((long) 5 * (original.getMinute() / 5) + 5) :
                        original.truncatedTo(ChronoUnit.HOURS)
                                .plusMinutes((long) 5 * (original.getMinute() / 5));
                break;
            case 15:
                mod = original.getMinute() % 15;
                nearest = mod >= 8 ?
                        original.truncatedTo(ChronoUnit.HOURS)
                                .plusMinutes((long) 15 * (original.getMinute() / 15) + 15) :
                        original.truncatedTo(ChronoUnit.HOURS)
                                .plusMinutes((long) 15 * (original.getMinute() / 15));
                break;
            default:
                nearest = original;
        }
        return nearest;
    }

You can try it with this unit test

 @Test
    void roundToTheNearestInterval() {
        //given
        LocalTime originalTime1 = LocalTime.of(6, 31, 15);
        LocalTime originalTime2 = LocalTime.of(19, 13, 42);
        LocalTime originalTime3 = LocalTime.of(6, 37, 11);
        LocalTime originalTime4 = LocalTime.of(19, 40, 34);
        Integer measurementInterval_5min = 5;
        Integer measurementInterval_15min = 15;

        MyService myService = new MyService();

        //when
        LocalTime rounded1_5min = myService.roundToTheNearestInterval(originalTime1, measurementInterval_5min);
        LocalTime rounded2_5min = myService.roundToTheNearestInterval(originalTime2, measurementInterval_5min);

        LocalTime rounded1_15min = myService.roundToTheNearestInterval(originalTime3, measurementInterval_15min);
        LocalTime rounded2_15min = myService.roundToTheNearestInterval(originalTime4, measurementInterval_15min);

        //then
        assertEquals(LocalTime.of(6, 30, 0), rounded1_5min);
        assertEquals(LocalTime.of(19, 15, 0), rounded2_5min);
        assertEquals(LocalTime.of(6, 30, 0), rounded1_15min);
        assertEquals(LocalTime.of(19, 45, 0), rounded2_15min);

    }