ZonedDateTime until() Method in Java with Examples

until() method of the ZonedDateTime class used to calculate the amount of time between two ZonedDateTime objects using TemporalUnit. The start and end points are this and the specified ZonedDateTime passed as a parameter. The result will be negative if the end is before the start. The calculation returns a whole number, representing the number of complete units between the two ZonedDateTime. This instance is immutable and unaffected by this method call. 

Syntax:

public long until(Temporal endExclusive, TemporalUnit unit)

Parameters: This method accepts two parameters endExclusive which is the end date, exclusive, which is converted to a ZonedDateTime and unit which is the unit to measure the amount. 

Return value: This method returns the amount of time between this ZonedDateTime and the end ZonedDateTime. 

Exception:This method throws following Exceptions:

• DateTimeException – if the amount cannot be calculated, or the ending temporal cannot be converted to a ZonedDateTime.
• UnsupportedTemporalTypeException – if the unit is not supported.
• ArithmeticException – if numeric overflow occurs.

Below programs illustrate the until() method: 

Program 1:

Java

// Java program to demonstrate
// ZonedDateTime.until() method

import java.time.*;
import java.time.temporal.*;

public class GFG {
    public static void main(String[] args)
    {
        // create ZonedDateTime objects
        ZonedDateTime z1
            = ZonedDateTime
                  .parse("2018-12-06T19:21:12.123+05:30[Asia/Calcutta]");

        ZonedDateTime z2
            = ZonedDateTime
                  .parse("2018-10-25T23:12:31.123+02:00[Europe/Paris]");

        // apply until method of ZonedDateTime class
        long result
            = z1.until(z2,
                       ChronoUnit.HOURS);

        // print results
        System.out.println("Result in HOURS: "
                           + result);
    }
}

Output:

Result in HOURS: -1000

Program 2:

Java

// Java program to demonstrate
// ZonedDateTime.until() method

import java.time.*;
import java.time.temporal.*;

public class GFG {
    public static void main(String[] args)
    {
        // create ZonedDateTime objects
        ZonedDateTime z1
            = ZonedDateTime
                  .parse("2018-12-06T19:21:12.123+05:30[Asia/Calcutta]");

        ZonedDateTime z2
            = ZonedDateTime
                  .parse("2018-10-25T23:12:31.123+02:00[Europe/Paris]");

        // apply until method of ZonedDateTime class
        long result
            = z2.until(z1,
                       ChronoUnit.DAYS);

        // print results
        System.out.println("Result in DAYS: "
                           + result);
    }
}

Output:

Result in DAYS: 41

References: https://docs.oracle.com/javase/10/docs/api/java/time/ZonedDateTime.html#until(java.time.temporal.Temporal, java.time.temporal.TemporalUnit)