Java LocalDateTime
last modified July 10, 2024
In this article we show how to work with LocalDateTime in Java.
LocalDateTime is an immutable date-time object that represents a date-time. It is a date-time without a time-zone in the ISO-8601 calendar system.
LocalDateTime does not store or represent a time-zone. It cannot
represent an instant on the time-line without additional information such as an
offset or time-zone. Value 2022-10-27T11:01:19.031990446 is an example of a
LocalDateTime.
Current datetime
The current time is retrived with LocalDateTime.now.
import java.time.LocalDateTime;
void main() {
var now = LocalDateTime.now();
System.out.println(now);
}
The example prints the current local datetime value.
$ java Main.java 2024-07-10T14:20:27.792280600
Creating LocalDateTime objects
The are several ways to create LocalDateTime.
import java.time.LocalDateTime;
import java.time.format.DateTimeFormatter;
void main() {
var now = LocalDateTime.now();
System.out.println(now);
LocalDateTime dt1 = LocalDateTime.of(2022, 10, 27, 10, 40, 55);
System.out.println(dt1);
LocalDateTime dt2 = LocalDateTime.parse("2020-11-27T11:20:50",
DateTimeFormatter.ISO_LOCAL_DATE_TIME);
System.out.println(dt2);
}
The program creates three datetime objects.
var now = LocalDateTime.now();
The current datetime is created with LocalDateTime.now.
LocalDateTime dt1 = LocalDateTime.of(2022, 10, 27, 10, 40, 55);
Here a localdatetime value is created with LocalDateTime.of.
We specify the year, month, day, hour, and second parts.
LocalDateTime dt2 = LocalDateTime.parse("2020-11-27T11:20:50",
DateTimeFormatter.ISO_LOCAL_DATE_TIME);
A localdatetime value is parsed from a string.
$ java Main.java 2024-07-10T14:21:17.484172200 2022-10-27T10:40:55 2020-11-27T11:20:50
LocalDateTime parts
In the next example, we get the current LocalDateTime value parts.
import java.time.LocalDateTime;
void main() {
LocalDateTime dt = LocalDateTime.now();
System.out.printf("Year: %s%n", dt.getYear());
System.out.printf("Month: %s%n", dt.getMonth());
System.out.printf("Day of month: %s%n", dt.getDayOfMonth());
System.out.printf("Hour: %s%n", dt.getHour());
System.out.printf("Minute: %s%n", dt.getMinute());
System.out.printf("Second: %s%n", dt.getSecond());
}
The getYear gets the year part, the getMonth the month
part, the getDayOfMonth gets the day of the month.
The getHour gets the hour part, the getMinute
gets the minute part, and the getSecond the second part.
$ java Main.java Year: 2024 Month: JULY Day of month: 10 Hour: 14 Minute: 17 Second: 2
LocalDateTime & DateTimeFormatter
The datetime is formatted differently in various countries.
DateTimeFormatter helps us format the datetime.
import java.time.LocalDateTime;
import java.time.format.DateTimeFormatter;
import java.time.format.FormatStyle;
void main() {
LocalDateTime now = LocalDateTime.now();
DateTimeFormatter dtf = DateTimeFormatter.ISO_TIME;
System.out.println(now.format(dtf));
DateTimeFormatter dtf2 = DateTimeFormatter.ofPattern("EEEE, MMM dd, yyyy HH:mm:ss a");
System.out.println(now.format(dtf2));
DateTimeFormatter dtf3 = DateTimeFormatter.ofLocalizedDateTime(FormatStyle.MEDIUM);
System.out.println(now.format(dtf3));
}
The example uses DateTimeFormatter to format time.
DateTimeFormatter dtf = DateTimeFormatter.ISO_TIME; System.out.println(now.format(dtf));
We format the time to the ISO format time standart.
DateTimeFormatter dtf2 = DateTimeFormatter.ofPattern("EEEE, MMM dd, yyyy HH:mm:ss a");
We can choose a specific time format with DateTimeFormatter.ofPattern.
The documentation to DateTimeFormatter contains the description
of various formatting characters that we can use.
DateTimeFormatter dtf3 = DateTimeFormatter.ofLocalizedDateTime(FormatStyle.MEDIUM);
Here we use the FormatStyle.MEDIUM format.
$ java Main.java 14:17:39.5461673 streda, júl 10, 2024 14:17:39 PM 10. 7. 2024, 14:17:39
LocalTime arithmetic
Java LocalDateTimeEx has methods for doing datetime arithmetics.
import java.time.LocalDateTime;
void main() {
LocalDateTime now = LocalDateTime.now();
System.out.println(now);
// LocalDateTime addition
System.out.println("Adding 4 years: " + now.plusYears(4));
System.out.println("Adding 11 months: " + now.plusMonths(11));
System.out.println("Adding 54 days: " + now.plusDays(54));
System.out.println("Adding 3 hours: " + now.plusHours(3));
System.out.println("Adding 30 minutes: " + now.plusMinutes(30));
System.out.println("Adding 45 seconds: " + now.plusSeconds(45));
System.out.println("Adding 40000 nanoseconds: " + now.plusNanos(40000));
System.out.println("-------------------------------------");
// LocalDateTime subtraction
System.out.println("Subtracting 4 years: " + now.minusYears(4));
System.out.println("Subtracting 11 months: " + now.minusMonths(11));
System.out.println("Subtracting 54 days: " + now.minusDays(54));
System.out.println("Subtracting 3 hours: " + now.minusHours(3));
System.out.println("Subtracting 30 minutes: " + now.minusMinutes(30));
System.out.println("Subtracting 45 seconds: " + now.minusSeconds(45));
System.out.println("Subtracting 40000 nanoseconds: " + now.minusNanos(40000));
}
The example presents method for adding and subtracting datetime units.
System.out.println("Adding 3 hours: " + localTime.plusHours(3));
The plusHours adds three hours to the current local time.
System.out.println("Subtracting 3 hours: " + now.minusHours(3));
Likewise, the minusHours subtracts three hours from the
current local time.
$ java Main.java 2024-07-10T14:18:29.986426300 Adding 4 years: 2028-07-10T14:18:29.986426300 Adding 11 months: 2025-06-10T14:18:29.986426300 Adding 54 days: 2024-09-02T14:18:29.986426300 Adding 3 hours: 2024-07-10T17:18:29.986426300 Adding 30 minutes: 2024-07-10T14:48:29.986426300 Adding 45 seconds: 2024-07-10T14:19:14.986426300 Adding 40000 nanoseconds: 2024-07-10T14:18:29.986466300 ------------------------------------- Subtracting 4 years: 2020-07-10T14:18:29.986426300 Subtracting 11 months: 2023-08-10T14:18:29.986426300 Subtracting 54 days: 2024-05-17T14:18:29.986426300 Subtracting 3 hours: 2024-07-10T11:18:29.986426300 Subtracting 30 minutes: 2024-07-10T13:48:29.986426300 Subtracting 45 seconds: 2024-07-10T14:17:44.986426300 Subtracting 40000 nanoseconds: 2024-07-10T14:18:29.986386300
LocalTime until
With the until method, we can compute the time until another time
in terms of the specified unit.
import java.time.LocalDateTime;
import java.time.temporal.ChronoUnit;
void main() {
LocalDateTime now = LocalDateTime.now();
LocalDateTime xmas = LocalDateTime.of(now.getYear(), 12, 24, 0, 0 ,0);
System.out.println(now);
System.out.println(xmas);
System.out.printf("%s hours%n", now.until(xmas, ChronoUnit.HOURS));
System.out.printf("%s minutes%n", now.until(xmas, ChronoUnit.MINUTES));
System.out.printf("%s seconds%n", now.until(xmas, ChronoUnit.SECONDS));
}
The example calculates the time that has to elapse until another time in hours, minutes and seconds.
System.out.printf("%s hours%n", now.until(time, ChronoUnit.HOURS));
With ChronoUnit.HOURS, we specify that we calculate the the time
difference in hours.
$ java Main.java 2024-07-10T14:19:00.847871600 2024-12-24T00:00 3993 hours 239620 minutes 14377259 seconds
LocalTime isBefore/isAfter
We can check if a datetime value is before or after another datetime value with
isBefore and isAfter.
import java.time.LocalDateTime;
void main() {
LocalDateTime now = LocalDateTime.now();
LocalDateTime dt1 = now.plusYears(3);
LocalDateTime dt2 = now.minusYears(3);
if (dt1.isAfter(now)) {
System.out.printf("%s is after %s%n", dt1, now);
}
if (dt2.isBefore(now)) {
System.out.printf("%s is before %s%n", dt2, now);
}
}
The program uses the isBefore and isAfter methods to
check the current datetime value against two other datetimes.
$ java Main.java 2025-10-27T12:25:45.261416509 is after 2022-10-27T12:25:45.261416509 2019-10-27T12:25:45.261416509 is before 2022-10-27T12:25:45.261416509
LocalDateTime truncate
The LocalDateTime's truncatedTo method returns a copy
of a local time with the time truncated. It returns a copy of the original
date-time with fields smaller than the specified unit set to zero.
import java.time.LocalDateTime;
import java.time.temporal.ChronoUnit;
void main() {
LocalDateTime now = LocalDateTime.now();
System.out.println(now);
System.out.println(now.truncatedTo(ChronoUnit.HALF_DAYS));
System.out.println(now.truncatedTo(ChronoUnit.HOURS));
System.out.println(now.truncatedTo(ChronoUnit.MINUTES));
System.out.println(now.truncatedTo(ChronoUnit.SECONDS));
System.out.println(now.truncatedTo(ChronoUnit.MICROS));
}
The example uses truncatedTo to truncate time to
half days, hours, minutes, seconds, and micros.
$ java Main.java 2024-07-10T14:19:49.389096800 2024-07-10T12:00 2024-07-10T14:00 2024-07-10T14:19 2024-07-10T14:19:49 2024-07-10T14:19:49.389096
Source
Java LocalDateTime - language reference
In this article we have worked with Java LocalDateTime.
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