How to calculate difference between two dates in Java


On this page, we are going to calculate the difference between two dates. Sometimes we have a requirement in our project to process the calculation or update any page on the differences of date.

Here we are going to discuss a simple scenario where we need to calculate the difference between two dates. Suppose retrieve the recode form table and display it on JSP and comes in tabular form and have a date column. Mark entire those row where difference btw date column in table and current is greater than seven.

Now we are going to use TimeUnit class of java.util.concurrent package. A TimeUnit represents time durations at a given unit of granularity and provides utility methods to convert across units and to perform timing and delay operations in these units. TimeUnit class available since JDK 1.5.

Calculation with TimeUnit class

DateDiffExp1.java
package org.websparrow;

import java.text.DateFormat;
import java.text.SimpleDateFormat;
import java.util.Date;
import java.util.concurrent.TimeUnit;

public class DateDiffExp1 {
	public static void main(String[] args) {
		// set the new date format
		DateFormat simpleDateFormat = new SimpleDateFormat("dd-MM-yyyy");

		Date currentDate = new Date();

		Date date1 = null;
		Date date2 = null;

		try {
			// calculating the difference b/w startDate and endDate
			String startDate = "01-01-2016";
			String endDate = simpleDateFormat.format(currentDate);

			date1 = simpleDateFormat.parse(startDate);
			date2 = simpleDateFormat.parse(endDate);

			long getDiff = date2.getTime() - date1.getTime();

			// using TimeUnit class from java.util.concurrent package
			long getDaysDiff = TimeUnit.MILLISECONDS.toDays(getDiff);

			System.out.println("Differance between date " + startDate + " and " + endDate + " is " + getDaysDiff + " days.");
		} catch (Exception e) {
			e.printStackTrace();
		}
	}
}

Output:

Differance between date 01-01-2016 and 26-12-2016 is 360 days.

Manual calculation

In this example, we are going to calculate the date difference using manual calculation. Before calculating manually these units must be known.

A nanosecond is defined as one thousandth of a microsecond, a microsecond as one thousandth of a millisecond, a millisecond as one thousandth of a second, a minute as sixty seconds, an hour as sixty minutes, and a day as twenty four hours.

24 hours = 1 day

60 minutes = 1 hour

60 seconds = 1 minute

1000 milliseconds = 1 second

DateDiffExp.java
package org.websparrow;

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

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

		DateFormat simpleDateFormat = new SimpleDateFormat("dd-MM-yyyy");

		Date currentDate = new Date();
		Date date1 = null;
		Date date2 = null;

		try {
			String startDate = "01-01-2016";
			String endDate = simpleDateFormat.format(currentDate);

			date1 = simpleDateFormat.parse(startDate);
			date2 = simpleDateFormat.parse(endDate);

			long getDiff = date2.getTime() - date1.getTime();

			long getDaysDiff = getDiff / (24 * 60 * 60 * 1000);

			System.out.println("Differance between date " + startDate + " and " + endDate + " is " + getDaysDiff + " days.");
		} catch (Exception e) {
			e.printStackTrace();
		}
	}

}

Output:

Differance between date 01-01-2016 and 26-12-2016 is 360 days.

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Websparrow
I like sharing my experiments and ideas with everyone by writing articles on the latest technological trends.