LocalDateTime withHour() method in Java with Examples

The withHour() method of LocalDateTime class in Java is used to get a copy of this LocalDateTime with the hours changed to the hours passed as the parameter to this method. The remaining values of this LocalDateTime remains the same.

Syntax:

public LocalDateTime withHour(int hours)

Parameter: This method accepts a single mandatory parameter hours which specifies the hours to be set in the resultant LocalDateTime instance. The value of this hours can range from 0 to 23.

Returns: The function returns a LocalDateTime instance with the hours changed to the hours passed as the parameter to this method. The remaining values of this LocalDateTime remains the same.

Exceptions: The function throws a DateTimeException if the hours value is invalid.

Below programs illustrate the LocalDateTime.withHour() method:

Program 1:

// Program to illustrate the withHour() method

import java.util.*;
import java.time.*;

public class GfG {
    public static void main(String[] args)
    {
        // Get the LocalDateTime instance
        LocalDateTime dt = LocalDateTime.now();

        // Get the String representation of this LocalDateTime
        System.out.println("Original LocalDateTime: "
                           + dt.toString());

        // Get a new LocalDateTime with hours 0
        System.out.println("New LocalDateTime: "
                           + dt.withHour(0));
    }
}

Output:

Original LocalDateTime: 2018-11-30T12:53:06.591
New LocalDateTime: 2018-11-30T00:53:06.591

Program 2:

// Program to illustrate the withHour() method

import java.util.*;
import java.time.*;

public class GfG {
    public static void main(String[] args)
    {
        // Get the LocalDateTime instance
        LocalDateTime dt
            = LocalDateTime
                  .parse("2015-04-06T10:15:30");

        // Get the String representation of this LocalDateTime
        System.out.println("Original LocalDateTime: "
                           + dt.toString());

        // Get a new LocalDateTime with hours 20
        System.out.println("New LocalDateTime: "
                           + dt.withHour(20));
    }
}

Output:

Original LocalDateTime: 2015-04-06T10:15:30
New LocalDateTime: 2015-04-06T20:15:30

Reference: https://docs.oracle.com/javase/10/docs/api/java/time/LocalDateTime.html#withHour(int)