How to find the number of days between two dates in java or groovy?

Question

I have a method which uses following logic to calculate difference between days.

long diff = milliseconds2 - milliseconds1;
long diffDays = diff / (24 * 60 * 60 * 1000);

but I want for ex, 9th feb 2011 to 19th feb 2011 should return me 11 days irrespective of second or milliseconds consideration. How can I achieve this?

Solution 1

For the groovy solution you asked for you should consider using this:

use(groovy.time.TimeCategory) {
   def duration = date1 - date2
   println "days: ${duration.days}, Hours: ${duration.hours}"
}

It's very easy to understand and extremely readable. You asked for a example how this can be used in an easy method which calculates the days between two dates. So here is your example.

class Example {

    public static void main(String[] args) {
        def lastWeek = new Date() - 7;
        def today = new Date()

        println daysBetween(lastWeek, today)
    }

    static def daysBetween(def startDate, def endDate) {
        use(groovy.time.TimeCategory) {
            def duration = endDate - startDate
            return duration.days
        }
    }
}

If you run this example it will print you 7. You can also enhance this method by using before() and after() to enable inverted dates.

Solution 2

It's a well worn line, but for Dates use JodaTime.

Here's how to calculate date intervals using JodaTime.

Days days = Days.daysBetween(new DateTime(millis1), new DateTime(millis2));
int daysBetweenDates = days.getDays();

Solution 3

  GregorianCalendar cal1 = new GregorianCalendar(2011,2,9); 
  GregorianCalendar cal2 = new GregorianCalendar(2011,2,19); 
  long ms1 = cal1.getTime().getTime(); 
  long ms2 = cal2.getTime().getTime(); 
  long difMs = ms2-ms1; 
  long msPerDay = 1000*60*60*24; 

  double days = difMs / msPerDay;

Solution 4

In groovy all you need is:

date2 - date1

which returns an integer representing the number of days between the two dates.

Or if you need to guard against reversal of order between the two Date instances (the operation returns negative numbers when the first operand is earlier than the second):

Math.abs(date2 - date1)

The above examples use the groovy date.minus(date) operator implementation which returns the number of days between the two dates.

Example groovy shell session:

$ groovysh
Groovy Shell (2.4.8, JVM: 1.8.0_111)
Type ':help' or ':h' for help.

groovy:000> x = new Date(1486382537168)
===> Mon Feb 06 13:02:17 CET 2017

groovy:000> y = new Date(1486000000000)
===> Thu Feb 02 02:46:40 CET 2017

groovy:000> x - y
===> 4

or if you need a method:

int daysBetween(date1, date2) {
    Math.abs(date2 - date1)
}

View more solutions

Comments

[maaz]

Hi thanks for your answer.. i didn't understand this.. how can make this as a function where i will pass two date object and it should return me difference between days?

[Christopher Klewes]

I added you an example for the function, please consider the improvement of your daysBetween() method with the before() check.

[maaz]

between 9th feb 2011 and 9th feb 2011 the difference should be 1 9th feb 2011 09:00 to 19th feb 14:00 should give me 11 days .

[Vishy]

This method will give 11 days regardless of the time. It will even give 11 for 9th feb 2011 23:00 and 19th feb 2011 01:00

[rudolfson]

Since Java 8 you could use the JDK's time API, too. See docs.oracle.com/javase/8/docs/api/index.html?java/time/…. In your case you could possibly use Period.between(date1, date2)

[Matias Bjarland]

as per below answer, for this specific problem and a groovy solution, you don't actually need to use TimeCategory, date1 - date2 is enough.

[Mario]

date2 - date1 is so groovy

[Pablo Pazos]

this is true for newer versions of Groovy, maybe this wasn't available back then

[Matias Bjarland]

I assume you are talking about the date.minus(date) method? Seems it's been in groovy since 1.6.0 so I guess that depends on what we mean by newer versions of groovy. I believe groovy 1.6.0 was released 2009.