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));    }} |
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));    }} |
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)
