In the previous three posts, we took a detailed look at the Java 8 Local Date and Time classes. In this post, we will take a look at the Java 8 provides ZonedDateTime and OffsetDateTime classes.
ZonedDateTime
ZonedDateTime uses ZoneId to represent different time zones. The following example shows how to create a ZoneId for Chicago
ZoneId zoneId = ZoneId.of("America/Chicago");
Following piece of code shows how to obtain a list of all zone ids.
Set zoneIdList = ZoneId.getAvailableZoneIds();
There are many ways to instantiate ZonedDateTime, most of them parallel LocalDateTime as shown in the previous post, with the addition of Zone Id.
ZonedDateTime zonedDateTime = ZonedDateTime.of(localDateTime, zoneId);
ZonedDateTime.parse("2015-05-03T10:15:30+01:00[America/Los_Angeles]");
Truncate Time from ZonedDateTime
The
truncateTo() method can be used to truncate the time fields. Any Time Unit lesser than the passed parameter will be marked to zero.
// Anything under days is set to zero. Works only for time.
System.out.println(zonedDateTime + " Truncated to " + zonedDateTime.truncatedTo(ChronoUnit.HOURS));
Convert Time Zone
Converting time from one timezone to another is one of the common requirements. The
method of ZonedDateTime can be used to convert a given ZonedDateTime to any timzone. The following example can be used to convert the current time in Chicago timezone to time in Los_Angeles
// Convert Time Zone
System.out.println(zonedDateTime + " in Los Angeles " + zonedDateTime.withZoneSameInstant(ZoneId.of("America/Los_Angeles")));
ZonedDateTime also offers many of the same utility methods offered by LocalDateTime. A few examples are shown below
System.out.println("3 days before today is : " + zonedDateTime.minus(3, ChronoUnit.DAYS));
System.out.println("3 decades before today is : " + zonedDateTime.minus(3, ChronoUnit.DECADES));
System.out.println("3 days after today is : " + zonedDateTime.plus(3, ChronoUnit.DAYS));
System.out.println("3 decades after today is : " + zonedDateTime.plus(3, ChronoUnit.DECADES));
System.out.println("The day of the week is : " + zonedDateTime.getDayOfWeek());
System.out.println("The day of the year is : " + zonedDateTime.getDayOfYear());
OffsetDateTime
OffsetDateTime class can be used to represent DateTime with an Offset. This class stores all date and time fields, to a precision of nanoseconds, as well as the offset from UTC/Greenwich. For example, the value "2nd October 2007 at 13:45.30.123456789 +02:00" can be stored in an OffsetDateTime. OffsetDateTime can be created in the following ways.
// Now
OffsetDateTime offsetDateTime = OffsetDateTime.now();
System.out.println("OffsetDateTime : " + offsetDateTime);
// Get LocalDateTime and apply Offset
LocalDateTime localDateTime = LocalDateTime.of(2017, Month.SEPTEMBER, 29, 5, 30);
ZoneOffset offset = ZoneOffset.of("+02:00");
OffsetDateTime offSetByTwo = OffsetDateTime.of(localDateTime, offset);
System.out.println(localDateTime + " Offset by two " + offSetByTwo);
Full code for this post
import java.time.LocalDateTime;
import java.time.Month;
import java.time.OffsetDateTime;
import java.time.ZoneId;
import java.time.ZoneOffset;
import java.time.ZonedDateTime;
import java.time.format.DateTimeFormatter;
import java.time.temporal.ChronoUnit;
public class ZonedDateTimeExamples {
public static void main(String[] args) {
ZonedDateTime zonedDateTime = ZonedDateTime.now(ZoneId.of("America/Chicago"));
System.out.println(zonedDateTime);
// Convert Time Zone
System.out
.println(zonedDateTime + " in Los Angeles " + zonedDateTime.withZoneSameInstant(ZoneId.of("America/Los_Angeles")));
// Anything under days is set to zero. Works only for time.
System.out.println(zonedDateTime + " Truncated to " + zonedDateTime.truncatedTo(ChronoUnit.HOURS));
System.out.println("3 days before today is : " + zonedDateTime.minus(3, ChronoUnit.DAYS));
System.out.println("3 decades before today is : " + zonedDateTime.minus(3, ChronoUnit.DECADES));
System.out.println("3 days after today is : " + zonedDateTime.plus(3, ChronoUnit.DAYS));
System.out.println("3 decades after today is : " + zonedDateTime.plus(3, ChronoUnit.DECADES));
System.out.println("The day of the week is : " + zonedDateTime.getDayOfWeek());
System.out.println("The day of the year is : " + zonedDateTime.getDayOfYear());
// Now
OffsetDateTime offsetDateTime = OffsetDateTime.now();
System.out.println("OffsetDateTime : " + offsetDateTime);
// Get LocalDateTime and apply Offset
LocalDateTime localDateTime = LocalDateTime.of(2017, Month.SEPTEMBER, 29, 5, 30);
ZoneOffset offset = ZoneOffset.of("+02:00");
OffsetDateTime offSetByTwo = OffsetDateTime.of(localDateTime, offset);
System.out.println(localDateTime + " Offset by two " + offSetByTwo);
}
}
