Joda-Time Create DateTime with Time Start Of the Day in Java

In this Joda-Time tutorial, we learn how to create a new DateTime object or convert an existing DateTime object to a new DateTime object with the time set to start of the day at 00:00:00.000 in Java.

Add Joda Time library to your Java project

To use Joda Time Java library in the Gradle build project, add the following dependency into the build.gradle file.

compile group: 'joda-time', name: 'joda-time', version: '2.10.9'

To use Joda Time Java library in the Maven build project, add the following dependency into the pom.xml file.

<dependency>
    <groupId>joda-time</groupId>
    <artifactId>joda-time</artifactId>
    <version>2.10.9</version>
</dependency>

To download the Joda Time .jar file you can visit Joda Time releases page at github.com/JodaOrg/joda-time

Convert to new DateTime with time set to start of the day

Joda-Time provides DateTime.withTimeAtStartOfDay() method that allows returning a copy of a DateTime object with the time set to start of the day.

TimeAtStartOfDayExample1.java

import org.joda.time.DateTime;

public class TimeAtStartOfDayExample1 {
    public static void main(String[] args) {
        DateTime dateTime = new DateTime();

        DateTime withTimeAtStartOfDay = dateTime.withTimeAtStartOfDay();

        System.out.println(dateTime);
        System.out.println(withTimeAtStartOfDay);
    }
}

The output is:

2021-01-17T17:15:32.402+07:00
2021-01-17T00:00:00.000+07:00

TimeAtStartOfDayExample2.java

import org.joda.time.DateTime;

public class TimeAtStartOfDayExample2 {
    public static void main(String[] args) {

        DateTime dateTime = DateTime.now().withTimeAtStartOfDay();

        System.out.println(dateTime);
    }
}