How to round time to the nearest quarter hour in java?
https://stackoverflow.com/questions/8723914
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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?
Solution
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);
OTHER TIPS
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
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
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.
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)
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());
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);
Maybe you can use an utility library for manipulating Dates, here for example you have a round method which can be useful for you:
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));
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();
}
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);
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.
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;
minutes = (int) (Math.round(minutes / 15.0) * 15.0);
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
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;
}
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();
}
