LocalDate atStartOfDay() method in Java with Examples

The atStartOfDay() method of LocalDate class in Java is combines this date with the time of midnight to create a LocalDateTime at the start of this date. Syntax:

public ZonedDateTime atStartOfDay(ZoneId zone)

Parameter: This method accepts a parameter zone which is the zone ID to be used and not necessary null. The parameter is not mandatory. Return Value: It returns the local date-time of midnight at the start of this date, not null. Below programs illustrate the atStartOfDay() method of LocalDate in Java: Program 1: 

Java

// Program to illustrate the atStartOfDay() method

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

public class GfG {
    public static void main(String[] args)
    {
        // parses the local date
        LocalDate dt = LocalDate.parse("2019-11-01");
        System.out.println(dt);

        // Function call
        LocalDateTime dt1 = dt.atStartOfDay();
        System.out.println(dt1);
    }
}

Output:

2019-11-01
2019-11-01T00:00

Program 2: Program with parameters. 

Java

// Program to illustrate the atStartOfDay() method

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

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

        // parses the local date
        LocalDate dt = LocalDate.parse("2018-01-20");
        System.out.println(dt);

        // Function call
        ZonedDateTime dt1 = dt.atStartOfDay(ZoneId.systemDefault());
        System.out.println(dt1);
    }
}

Output:

2018-01-20
2018-01-20T00:00Z[Etc/UTC]

Reference: https://docs.oracle.com/javase/10/docs/api/java/time/LocalDate.html#atStartOfDay()