Java ZonedDateTime class

java.time.ZonedDateTime class, introduced in Java 8, represents a date and time with timezone information in ISO-8601 calendar system. This class stores all date and time fields, to a precision of nanoseconds.

We can use the ZonedDateTime instances where we need to represent the time for globally distributed users. For example, we can use ZonedDateTime to communicate a conference date where joiners will connect online based on their local date and time.

A ZonedDateTime holds state equivalent to three separate objects, a LocalDateTime, a ZoneId and the resolved ZoneOffset.

Note that ZonedDateTime instances are immutable and thread-safe.

1. ZonedDateTime class declaration

public final class ZonedDateTime
	extends Object
	implements Temporal, ChronoZonedDateTime<LocalDate>, Serializable
{
	//class body
}

2. How to create ZonedDateTime

Generally, we will be creating ZonedDateTime instances in two conditions i.e. get current timestamp with zone information or create represent a timestamp in a specific timezone.

2.1. Get current ZonedDateTime

Use following factory method to get the current timestamp.

ZonedDateTime now = ZonedDateTime.now();

ZonedDateTime now = ZonedDateTime.now( ZoneId.of("GMT+05:30") ); //Time in IST

2.2. Create specified ZonedDateTime

To create a timestamp with specific date, time and zone information – use below methods.

//1 - All date parts are inplace
ZoneId zoneId = ZoneId.of("UTC+1");

ZonedDateTime zonedDateTime1 =
    ZonedDateTime.of(2015, 11, 30, 23, 45, 59, 1234, zoneId);

//=========

//2 - Using existing local date and time values 
LocalDate localDate = LocalDate.of(2019, 03, 12);
LocalTime localTime = LocalTime.of(12,  44);
ZoneId zoneId = ZoneId.of("GMT+05:30");

ZonedDateTime timeStamp = ZonedDateTime.of( localDate, localTime, zoneId );

3. How to parse string to ZonedDateTime

The ZonedDateTime class has two overloaded parse() methods to convert time in string to local time instance.

parse(CharSequence text)	//1

parse(CharSequence text, DateTimeFormatter formatter)	//2

• Use first method if the string contains time in ISO_ZONED_DATE_TIME pattern i.e. 2019-03-28T10:15:30+01:00[Europe/Paris]. This is default pattern.
• For any other date-time pattern, we need to use second method where we pass the date-time as string as well as a formatter which represents the pattern of that date-time string.

//1 - default pattern
String timeStamp = "2019-03-27T10:15:30";
ZonedDateTime localTimeObj = ZonedDateTime.parse(time);

//2 - specified pattern
DateTimeFormatter formatter = DateTimeFormatter.ofPattern("yyyy-MM-dd HH:mm:ss a");
String timeStamp1 = "2019-03-27 10:15:30 AM";
ZonedDateTime localTimeObj1 = ZonedDateTime.parse(timeStamp1, formatter);

4. How to format ZonedDateTime to string

Use ZonedDateTime.format(DateTimeFormatter) method to format a local time to a desired string representation.

DateTimeFormatter formatter = DateTimeFormatter.ofPattern("yyyy-MM-dd HH:mm:ss a");

ZonedDateTime now = ZonedDateTime.now();

String dateTimeString = now.format(formatter);	//2019-03-28 14:47:33 PM

5. How to modify ZonedDateTime

ZonedDateTime provides below methods for modifications. All methods return a new instance of ZonedDateTime because existing instance is always immutable.

• plusYears()
• plusMonths()
• plusDays()
• plusHours()
• plusMinutes()
• plusSeconds()
• plusNanos()
• minusYears()
• minusMonths()
• minusDays()
• minusHours()
• minusMinutes()
• minusSeconds()
• minusNanos()

ZonedDateTime now = ZonedDateTime.now();

//3 hours later
ZonedDateTime zonedDateTime1 = now.plusHours(3);	

//3 minutes earliar
ZonedDateTime zonedDateTime2 = now.minusMinutes(3);

//Next year same time
ZonedDateTime zonedDateTime2 = now.plusYears(1);

//Last year same time
ZonedDateTime zonedDateTime2 = now.minusYears(1);

6. More Examples

Format ZonedDateTime to String
Parse string to ZonedDateTime
Convert LocalDate to ZonedDateTime in Java
ZonedDateTime timezone conversion example
Compare ZonedDateTime instances
Java 8 – Parse string to date-time in UTC

Drop me your questions related to Java 8 ZonedDateTime class in comments.

Happy Learning !!

Ref : ZonedDateTime Java Doc