Java 8 – Convert date and time between timezone

1. Overview

In this tutorial, We'll learn how to convert date and time between timezone  using new java 8 date time api.

There is another case where flight timings will be difficult to calculate based on the arriving city. Flight starts from San Francisco (SFO) at 11:00 AM and arrives in Dubai(DXB) at 23:20. This journey takes up to 24 hours 20 minutes but when we see it looks like 12 hours 20 minutes. This is because of timezone differences.

Finally, We'll explore how to solve flight problem using java 8 ZonedDateTime api.

2. Java 8 and Beyond Flight Timing TimeZone Conversion

Example program to convert IST time to PST and PST to GST adding 24 hours 20 mins.

How to create a simple flight time calculation based on the time duration.

Flight starts at San Francisco (SFO): 11:00 AM 

Arrives in Dubai(DXB) : 23:20 PM. 

This journey almost takes up to 24 hours 20 minutes but if you see the time difference it is just 12 hours 20 minutes and it was wrong understanding because of timezone change.

Look at the below example code that shows the exact arrival time after adding 24 hours and 20 mins to the start time with java 8 date time api. After that destination time will be the exact one shown above.

And also we are going to see the time difference between start and destination date times in days with considering the timezones using Duration.between().

package com.javaprogramto.java8.dates.timezone.conversion;

import java.time.Duration;
import java.time.LocalDateTime;
import java.time.ZoneId;
import java.time.ZonedDateTime;
import java.time.format.DateTimeFormatter;
import java.time.temporal.ChronoUnit;

public class Java8FilghtTimingsTimeZoneConversion {

	public static void main(String[] args) {

		// Current date and time using now()
		LocalDateTime currentDateTime = LocalDateTime.of(2020, 12, 01, 11, 00);

		// Creating two timezone zoneid objects using ZoneId.of() method.
		ZoneId losAngelesTimeZone = ZoneId.of("America/Los_Angeles");
		ZoneId dubaiTimeZone = ZoneId.of("Asia/Dubai");

		// Converting Current timezone time to Log Angeles time
		ZonedDateTime losAngelesDateTime = currentDateTime.atZone(losAngelesTimeZone);

		// Converting Current timezone time to Dubai time
		ZonedDateTime dubaiDateTime = losAngelesDateTime.withZoneSameInstant(dubaiTimeZone).plusHours(24).plusMinutes(20);

		// Datetime formatting 
		DateTimeFormatter formatter = DateTimeFormatter.ofPattern("yyyy-MMM-dd HH:mm");
		
		// Print all 3 dates
		System.out.println("Current time in IST : " + formatter.format(currentDateTime));
		System.out.println("Los Angeles time now : " + formatter.format(losAngelesDateTime));
		System.out.println("Dubai time now : " + formatter.format(dubaiDateTime));

		// getting the diff b/w two los angeles and dubai times.
		printDurationBetweenTwoDates(losAngelesDateTime, dubaiDateTime);

	}

	private static void printDurationBetweenTwoDates(ZonedDateTime sfoDateTime, ZonedDateTime dubaiDateTime) {
		Duration d = Duration.between(sfoDateTime, dubaiDateTime);
		long days = d.get(ChronoUnit.SECONDS);
		System.out.println("Time Difference between los angeles and dubai : " + days / (60 * 60) + " Hours " + (days % (60 * 60)) / 60 + " Minites");

	}

}
 

Output:

Current time in IST : 2020-Dec-01 11:00
Los Angeles time now : 2020-Dec-01 11:00
Dubai time now : 2020-Dec-02 23:20
Time Difference between los angeles and dubai : 24 Hours 20 Minites
 

3. Conclusion

In this article, we've seen how to convert the date between timezones and convert from one timezone to another.

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