In this article, we will learn how to convert LocalDateTime to GregorianCalendar using atZone() method of LocalDateTime provided in Java 1.8 version and vice-versa
LocalDateTime to GregorianCalendar conversion & vice-versa :
- There are 3 new methods introduced in Java 1.8 version for GregorianCalendar class, those are
- from(ZonedDateTime) – This static method obtains an instance of
GregorianCalendarwith the default locale from aZonedDateTimeobject - toZonedDateTime() – This method converts invoking GregorianCalendar object to a
ZonedDateTimethat represents the same point on the time-line as that ofGregorianCalendarobject - getCalendarType() – Returns
"gregory"as the calendar type
- from(ZonedDateTime) – This static method obtains an instance of
1. Convert LocalDateTime to GregorianCalendar :
- LocalDateTime consists of only Date & Time information but doesn’t have Zone information whereas GregorianCalendar requires all 3 Date, Time and Zone informations
- GregorianCalendar = LocalDateTime + Zone information
- For LocalDateTime to GregorianCalendar conversion, Time-Zone information is required
- GregorianCalendar.from() method accepts ZonedDateTime as input-argument and returns GregorianCalendar
- Convert LocalDateTime to ZonedDateTime using atZone() method passing ZoneId as argument
- Pass converted ZonedDateTime object as argument to GregorianCalendar.from() method which will return GregorianCalendar
- Converted GregorianCalendar will have,
- Date & Time parts are same as that of LocalDateTime
- Adding System default Zone information
- In short, LocalDateTime -> ZonedDateTime -> GregorianCalendar
- Lets see an example for conversion of LocalDateTime to GregorianCalendar in the below illustration
ConvertLocalDateTimeToGregorianCalendar.java
package in.bench.resources.java8.localdatetime.examples;
import java.time.LocalDateTime;
import java.time.ZoneId;
import java.util.GregorianCalendar;
public class ConvertLocalDateTimeToGregorianCalendar {
public static void main(String[] args) {
// 1. get current System Date/time
LocalDateTime localDateTime = LocalDateTime.now();
System.out.println("Current System Date/time is :- \n"
+ localDateTime);
// 2. get system default zone
ZoneId zoneId = ZoneId.systemDefault();
System.out.println("\nDefault System Zone is :- \n"
+ zoneId);
// 3. convert LocalDate -> ZonedDateTime -> GregorianCalendar
GregorianCalendar gregorianCalendar = GregorianCalendar
.from(localDateTime.atZone(zoneId));
// 4. print to console
System.out.print("\nConversion of LocalDateTime to GregorianCalendar is :- \n"
+ gregorianCalendar.getTime());
}
}
Output:
Current System Date/time is :-
2022-08-09T18:09:26.409969600
Default System Zone is :-
Asia/Calcutta
Conversion of LocalDateTime to GregorianCalendar is :-
Tue Aug 09 18:09:26 IST 2022
2. Convert GregorianCalendar to LocalDateTime :
- Instantiate GregorianCalendar object for conversion to LocalDateTime
- Conversion steps –
- Convert GregorianCalendar to ZonedDateTime using toZonedDateTime() method
- And then invoke toLocalDateTime() method which returns LocalDateTime
- In short, GregorianCalendar -> ZonedDateTime -> LocalDateTime
- Lets see an example for conversion of GregorianCalendar to LocalDateTime in the below illustration
ConvertGregorianCalendarToLocalDateTime.java
package in.bench.resources.java8.localdatetime.examples;
import java.time.LocalDateTime;
import java.time.ZoneId;
import java.util.GregorianCalendar;
public class ConvertGregorianCalendarToLocalDateTime {
public static void main(String[] args) {
// 1. Instantiate GregorianCalendar
GregorianCalendar gregorianCalendar = new GregorianCalendar();
System.out.println("Current Date/Time is :- \n"
+ gregorianCalendar.getTime());
// 2. get system default zone
ZoneId zoneId = ZoneId.systemDefault();
System.out.println("\nDefault System Zone is :- \n"
+ zoneId);
// 3. convert GregorianCalendar -> ZonedDateTime -> LocalDateTime
LocalDateTime localDateTime = gregorianCalendar
.toZonedDateTime()
.toLocalDateTime();
// 4. print to console
System.out.print("\nConversion of GregorianCalendar to LocalDateTime is :- \n"
+ localDateTime);
}
}
Output:
Current Date/Time is :-
Tue Aug 09 18:09:44 IST 2022
Default System Zone is :-
Asia/Calcutta
Conversion of GregorianCalendar to LocalDateTime is :-
2022-08-09T18:09:44.739
Related Articles:
- Java 8 – LocalDateTime with method details and examples
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- Java 8 – How to convert LocalDateTime to GregorianCalendar and vice-versa ?
- Java 8 – How to convert LocalDateTime to XMLGregorianCalendar and vice-versa ?
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- Java 8 – How to check whether a LocalDateTime is Before another LocalDateTime ?
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- Java 8 – What are all the Temporal Fields supported by LocalDateTime ?
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- More Java 8 Date/Time API examples
References:
- https://docs.oracle.com/javase/8/docs/api/java/time/LocalDateTime.html
- https://docs.oracle.com/javase/8/docs/api/java/time/Instant.html
- https://docs.oracle.com/javase/8/docs/api/java/time/ZonedDateTime.html
- https://docs.oracle.com/javase/8/docs/api/java/time/ZoneId.html
- https://docs.oracle.com/javase/7/docs/api/java/util/GregorianCalendar.html
- https://docs.oracle.com/javase/8/docs/api/java/util/Date.html
- https://docs.oracle.com/javase/8/docs/api/java/util/Calendar.html
- https://docs.oracle.com/javase/8/docs/api/java/sql/Timestamp.html
Happy Coding !!
Happy Learning !!