Home » Java » Number of days between two dates in Joda-Time

Number of days between two dates in Joda-Time

Posted by: admin November 2, 2017 Leave a comment

Questions:

How do I find the difference in Days between two Joda-Time DateTime instances?
With ‘difference in days’ I mean if start is on Monday and end is on Tuesday I expect a return value of 1 regardless of the hour/minute/seconds of the start and end dates.

Days.daysBetween(start, end).getDays() gives me 0 if start is in the evening and end in the morning.

I’m also having the same issue with other date fields so I was hoping there would be a generic way to ‘ignore’ the fields of lesser significance.

In other words, the months between Feb and 4 March would also be 1, as would the hours between 14:45 and 15:12 be. However the hour difference between 14:01 and 14:55 would be 0.

Answers:

Annoyingly, the withTimeAtStartOfDay answer is wrong, but only occasionally. You want:

Days.daysBetween(start.toLocalDate(), end.toLocalDate()).getDays()

It turns out that “midnight/start of day” sometimes means 1am (daylight savings happen this way in some places), which Days.daysBetween doesn’t handle properly.

// 5am on the 20th to 1pm on the 21st, October 2013, Brazil
DateTimeZone BRAZIL = DateTimeZone.forID("America/Sao_Paulo");
DateTime start = new DateTime(2013, 10, 20, 5, 0, 0, BRAZIL);
DateTime end = new DateTime(2013, 10, 21, 13, 0, 0, BRAZIL);
System.out.println(daysBetween(start.withTimeAtStartOfDay(),
                               end.withTimeAtStartOfDay()).getDays());
// prints 0
System.out.println(daysBetween(start.toLocalDate(),
                               end.toLocalDate()).getDays());
// prints 1

Going via a LocalDate sidesteps the whole issue.

Questions:
Answers:

Days Class

Using the Days class with the withTimeAtStartOfDay method should work:

Days.daysBetween(start.withTimeAtStartOfDay() , end.withTimeAtStartOfDay() ).getDays() 

Questions:
Answers:

you can use LocalDate:

Days.daysBetween(new LocalDate(start), new LocalDate(end)).getDays() 

Questions:
Answers:

The accepted answer builds two LocalDate objects, which are quite expensive if you are reading lot of data.
I use this:

  public static int getDaysBetween(DateTime earlier, DateTime later)
  {
    return (int) TimeUnit.MILLISECONDS.toDays(later.getMillis()- earlier.getMillis());
  }

By calling getMillis() you use already existing variables.
MILLISECONDS.toDays() then, uses a simple arithmetic calculation, does not create any object.

Questions:
Answers:

tl;dr

java.time.temporal.ChronoUnit.DAYS.between( 
    earlier.truncatedTo( ChronoUnit.DAYS )  , 
    later.truncatedTo( ChronoUnit.DAYS ) 
)

…or…

java.time.temporal.ChronoUnit.HOURS.between( 
    earlier.truncatedTo( ChronoUnit.HOURS )  , 
    later.truncatedTo( ChronoUnit.HOURS ) 
)

java.time

FYI, the Joda-Time project is now in maintenance mode, with the team advising migration to the java.time classes.

The equivalent of Joda-Time DateTime is ZonedDateTime.

ZoneId z = ZoneId.of( "Pacific/Auckland" ) ;
ZonedDateTime now = ZonedDateTime.now( z ) ;

Apparently you want to count the days by dates, meaning you want to ignore the time of day. For example, starting a minute before midnight and ending a minute after midnight should result in a single day. For this behavior, extract a LocalDate from your ZonedDateTime. The LocalDate class represents a date-only value without time-of-day and without time zone.

LocalDate localDateStart = zdtStart.toLocalDate() ;
LocalDate localDateStop = zdtStop.toLocalDate() ;

Use the ChronoUnit enum to calculate elapsed days or other units.

long days = ChronoUnit.DAYS.between( localDateStart , localDateStop ) ;

Truncate

As for you asking about a more general way to do this counting where you are interested the delta of hours as hour-of-the-clock rather than complete hours as spans-of-time of sixty minutes, use the truncatedTo method.

Here is your example of 14:45 to 15:12 on same day.

ZoneId z = ZoneId.of( "America/Montreal" ); 
ZonedDateTime start = ZonedDateTime.of( 2017 , 1 , 17 , 14 , 45 , 0 , 0 , z );
ZonedDateTime stop = ZonedDateTime.of( 2017 , 1 , 17 , 15 , 12 , 0 , 0 , z );

long hours = ChronoUnit.HOURS.between( start.truncatedTo( ChronoUnit.HOURS ) , stop.truncatedTo( ChronoUnit.HOURS ) );

1

For a count of days by dates, truncate to ChronoUnit.DAYS. Here is an example rolling over midnight from five minutes before to five minutes after, for elapsed days of 1.

ZoneId z = ZoneId.of( "America/Montreal" );
ZonedDateTime start = ZonedDateTime.of( 2017 , 1 , 17 , 23 , 55 , 0 , 0 , z );
ZonedDateTime stop = ZonedDateTime.of( 2017 , 1 , 18 , 00 , 05 , 0 , 0 , z );

long days = ChronoUnit.DAYS.between( start.truncatedTo( ChronoUnit.DAYS ) , stop.truncatedTo( ChronoUnit.DAYS ) );

1


About java.time

The java.time framework is built into Java 8 and later. These classes supplant the troublesome old legacy date-time classes such as java.util.Date, Calendar, & SimpleDateFormat.

The Joda-Time project, now in maintenance mode, advises migration to the java.time classes.

To learn more, see the Oracle Tutorial. And search Stack Overflow for many examples and explanations. Specification is JSR 310.

Where to obtain the java.time classes?

The ThreeTen-Extra project extends java.time with additional classes. This project is a proving ground for possible future additions to java.time. You may find some useful classes here such as Interval, YearWeek, YearQuarter, and more.

Questions:
Answers:
public static int getDifferenceIndays(long timestamp1, long timestamp2) {
    final int SECONDS = 60;
    final int MINUTES = 60;
    final int HOURS = 24;
    final int MILLIES = 1000;
    long temp;
    if (timestamp1 < timestamp2) {
        temp = timestamp1;
        timestamp1 = timestamp2;
        timestamp2 = temp;
    }
    Calendar startDate = Calendar.getInstance(TimeZone.getDefault());
    Calendar endDate = Calendar.getInstance(TimeZone.getDefault());
    endDate.setTimeInMillis(timestamp1);
    startDate.setTimeInMillis(timestamp2);
    if ((timestamp1 - timestamp2) < 1 * HOURS * MINUTES * SECONDS * MILLIES) {
        int day1 = endDate.get(Calendar.DAY_OF_MONTH);
        int day2 = startDate.get(Calendar.DAY_OF_MONTH);
        if (day1 == day2) {
            return 0;
        } else {
            return 1;
        }
    }
    int diffDays = 0;
    startDate.add(Calendar.DAY_OF_MONTH, diffDays);
    while (startDate.before(endDate)) {
        startDate.add(Calendar.DAY_OF_MONTH, 1);
        diffDays++;
    }
    return diffDays;
}