Tag: datetime

In this tutorial, we show you 2 examples to calculate date / time difference in Java :

1. Manual time calculation.
2. Joda time library.

1. Manual time calculation

Converts Date in milliseconds (ms) and calculate the differences between two dates, with following rules:

1000 milliseconds = 1 second
60 seconds = 1 minute
60 minutes = 1 hour
24 hours = 1 day

Class DateDiferentExample.java

package br.com.ziben.date;

import java.text.SimpleDateFormat;
import java.util.Date;

public class DateDifferentExample {

	public static void main(String[] args) {

		String dateStart = "01/30/2013 09:29:58";
		String dateStop = "01/31/2013 10:31:48";

		// HH converts hour in 24 hours format (0-23), day calculation
		SimpleDateFormat format = new SimpleDateFormat("MM/dd/yyyy HH:mm:ss");

		Date d1 = null;
		Date d2 = null;

		try {
			d1 = format.parse(dateStart);
			d2 = format.parse(dateStop);

			// in milliseconds
			long diff = d2.getTime() - d1.getTime();

			long diffSeconds = diff / 1000 % 60;
			long diffMinutes = diff / (60 * 1000) % 60;
			long diffHours = diff / (60 * 60 * 1000) % 24;
			long diffDays = diff / (24 * 60 * 60 * 1000);

			System.out.print(diffDays + " days, ");
			System.out.print(diffHours + " hours, ");
			System.out.print(diffMinutes + " minutes, ");
			System.out.print(diffSeconds + " seconds.");

		} catch (Exception e) {
			e.printStackTrace();
		}
 	}
}

Result…

1 days, 1 hours, 1 minutes, 50 seconds.

Why seconds and minutes need %60, and hours %24? If you change it to:

long diffSeconds = diff / 1000;

The result will be

1 days, 1 hours, 1 minutes, 90110 seconds.

The “90110” is the total number of seconds difference between date1 and date2, this is correct if you want to know the differences in seconds ONLY.

To display difference in “day, hour, minute and second” format, you should use a modulus (%60) to cut off the remainder of seconds (90060). Got it? The idea is applied in minutes (%60) and hours (%24) as well.

90110 % 60 = 50 seconds (you want this)
90110 - 50 = 90060 seconds (you dont want this)

2. Joda Time Example

Here’s the equivalent example, but using Joda time to calculate differences between two dates.

P.S This example is using joda-time-2.1.jar

Class JodaDateDifferentExample.java

package br.com.ziben.date;

import java.text.SimpleDateFormat;
import java.util.Date;

import org.joda.time.DateTime;
import org.joda.time.Days;
import org.joda.time.Hours;
import org.joda.time.Minutes;
import org.joda.time.Seconds;

public class JodaDateDifferentExample {

  public static void main(String[] args) {

	String dateStart = "01/30/2013 09:29:58";
	String dateStop = "01/31/2013 10:31:48";

	SimpleDateFormat format = new SimpleDateFormat("MM/dd/yyyy HH:mm:ss");

	Date d1 = null;
	Date d2 = null;

	try {
		d1 = format.parse(dateStart);
		d2 = format.parse(dateStop);

		DateTime dt1 = new DateTime(d1);
		DateTime dt2 = new DateTime(d2);

		System.out.print(Days.daysBetween(dt1, dt2).getDays() + " days, ");
		System.out.print(Hours.hoursBetween(dt1, dt2).getHours() % 24 + " hours, ");
		System.out.print(Minutes.minutesBetween(dt1, dt2).getMinutes() % 60 + " minutes, ");
		System.out.print(Seconds.secondsBetween(dt1, dt2).getSeconds() % 60 + " seconds.");

	 } catch (Exception e) {
		e.printStackTrace();
	 }
  }

}

Result:

1 days, 1 hours, 1 minutes, 50 seconds.

Let me know if you have alternative ways 🙂