ChronoLocalDateTime getLong() method in Java with Examples

The getLong() method of ChronoLocalDateTime interface in Java is used to get the value of the specified field passed as input from this ChronoLocalDateTime as an long value.This method queries this ChronoLocalDateTime for the value of the field and the returned value will always be within the valid range of values for the field. When the field is not supported and the method is unable to return int value then an exception is thrown.

Syntax:

long getLong(TemporalField field)

Parameters: This method accepts a single parameter field which represents the field to get. This is a mandatory parameter and it should not be null.

Return value: This method returns an int value for the field.

Exception: This method throws following exceptions:

• DateTimeException: if a value for the field cannot be obtained or the value is outside the range of valid values for the field.
• UnsupportedTemporalTypeException: if the field is not supported or the range of values exceeds an int.
• ArithmeticException: if numeric overflow occurs.

Below programs illustrate the getLong() method:
Program 1:

// Java program to demonstrate
// ChronoLocalDateTime.getLong() method

import java.time.*;
import java.time.chrono.*;
import java.time.temporal.ChronoField;

public class GFG {
    public static void main(String[] args)
    {

        // create a ChronoLocalDateTime object
        ChronoLocalDateTime localDT
            = LocalDateTime
                  .parse("2019-12-31T19:15:30");

        // get all enum of chronofield
        // and iterate through all enum values
        for (ChronoField field : ChronoField.values()) {

            try {
                // get long value of field
                long value = localDT.getLong(field);
                System.out.println(field
                                   + " : "
                                   + value);
            }
            catch (Exception e) {
                System.out.println("e " + field);
            }
        }
    }
}

Output:

NanoOfSecond : 0
NanoOfDay : 69330000000000
MicroOfSecond : 0
MicroOfDay : 69330000000
MilliOfSecond : 0
MilliOfDay : 69330000
SecondOfMinute : 30
SecondOfDay : 69330
MinuteOfHour : 15
MinuteOfDay : 1155
HourOfAmPm : 7
ClockHourOfAmPm : 7
HourOfDay : 19
ClockHourOfDay : 19
AmPmOfDay : 1
DayOfWeek : 2
AlignedDayOfWeekInMonth : 3
AlignedDayOfWeekInYear : 1
DayOfMonth : 31
DayOfYear : 365
EpochDay : 18261
AlignedWeekOfMonth : 5
AlignedWeekOfYear : 53
MonthOfYear : 12
ProlepticMonth : 24239
YearOfEra : 2019
Year : 2019
Era : 1
e InstantSeconds
e OffsetSeconds

Program 2:

// Java program to demonstrate
// ChronoLocalDateTime.getLong() method

import java.time.*;
import java.time.chrono.*;
import java.time.temporal.ChronoField;

public class GFG {
    public static void main(String[] args)
    {

        // create a ChronoLocalDateTime object
        ChronoLocalDateTime localDT
            = LocalDateTime
                  .parse("2018-10-25T23:12:31.123");

        // try to find AMPM_OF_DAY
        // using ChronoField.AMPM_OF_DAY
        // in getLong method
        try {

            long value
                = localDT.getLong(
                    ChronoField.AMPM_OF_DAY);

            // print result
            System.out.println("AMPM_OF_DAY value: "
                               + value);
        }
        catch (Exception e) {

            // print exception
            System.out.println("Exception: " + e);
        }
    }
}

Output:

AMPM_OF_DAY value: 1

Reference: https://docs.oracle.com/javase/9/docs/api/java/time/temporal/TemporalAccessor.html#getLong-java.time.temporal.TemporalField-