Android/Java - Date Difference in days

Question

I am getting the current date (in format 12/31/1999 i.e. mm/dd/yyyy) as using the below code:

Textview txtViewData;
txtViewDate.setText("Today is " +
        android.text.format.DateFormat.getDateFormat(this).format(new Date()));

and I am having another date in format as: 2010-08-25 (i.e. yyyy/mm/dd) ,

so I want to find the difference between date in number of days, how do I find difference in days?

(In other words, I want to find the difference between CURRENT DATE - yyyy/mm/dd formatted date)

Answer 1

This fragment accounts for daylight savings time and is O(1).

private final static long MILLISECS_PER_DAY = 24 * 60 * 60 * 1000;

private static long getDateToLong(Date date) {
    return Date.UTC(date.getYear(), date.getMonth(), date.getDate(), 0, 0, 0);
}

public static int getSignedDiffInDays(Date beginDate, Date endDate) {
    long beginMS = getDateToLong(beginDate);
    long endMS = getDateToLong(endDate);
    long diff = (endMS - beginMS) / (MILLISECS_PER_DAY);
    return (int)diff;
}

public static int getUnsignedDiffInDays(Date beginDate, Date endDate) {
    return Math.abs(getSignedDiffInDays(beginDate, endDate));
}

Answer 2

use these functions

    public static int getDateDifference(int previousYear, int previousMonthOfYear, int previousDayOfMonth, int nextYear, int nextMonthOfYear, int nextDayOfMonth, int differenceToCount){
    // int differenceToCount = can be any of the following
    //  Calendar.MILLISECOND;
    //  Calendar.SECOND;
    //  Calendar.MINUTE;
    //  Calendar.HOUR;
    //  Calendar.DAY_OF_MONTH;
    //  Calendar.MONTH;
    //  Calendar.YEAR;
    //  Calendar.----

    Calendar previousDate = Calendar.getInstance();
    previousDate.set(Calendar.DAY_OF_MONTH, previousDayOfMonth);
    // month is zero indexed so month should be minus 1
    previousDate.set(Calendar.MONTH, previousMonthOfYear);
    previousDate.set(Calendar.YEAR, previousYear);

    Calendar nextDate = Calendar.getInstance();
    nextDate.set(Calendar.DAY_OF_MONTH, previousDayOfMonth);
    // month is zero indexed so month should be minus 1
    nextDate.set(Calendar.MONTH, previousMonthOfYear);
    nextDate.set(Calendar.YEAR, previousYear);

    return getDateDifference(previousDate,nextDate,differenceToCount);
}
public static int getDateDifference(Calendar previousDate,Calendar nextDate,int differenceToCount){
    // int differenceToCount = can be any of the following
    //  Calendar.MILLISECOND;
    //  Calendar.SECOND;
    //  Calendar.MINUTE;
    //  Calendar.HOUR;
    //  Calendar.DAY_OF_MONTH;
    //  Calendar.MONTH;
    //  Calendar.YEAR;
    //  Calendar.----

    //raise an exception if previous is greater than nextdate.
    if(previousDate.compareTo(nextDate)>0){
        throw new RuntimeException("Previous Date is later than Nextdate");
    }

    int difference=0;
    while(previousDate.compareTo(nextDate)<=0){
        difference++;
        previousDate.add(differenceToCount,1);
    }
    return difference;
}

Answer 3

Joda-Time

Best way is to use Joda-Time, the highly successful open-source library you would add to your project.

String date1 = "2015-11-11";
String date2 = "2013-11-11";
DateTimeFormatter formatter = new DateTimeFormat.forPattern("yyyy-MM-dd");
DateTime d1 = formatter.parseDateTime(date1);
DateTime d2 = formatter.parseDateTime(date2);
long diffInMillis = d2.getMillis() - d1.getMillis();

Duration duration = new Duration(d1, d2);
int days = duration.getStandardDays();
int hours = duration.getStandardHours();
int minutes = duration.getStandardMinutes();

If you're using Android Studio, very easy to add joda-time. In your build.gradle (app):

dependencies {
  compile 'joda-time:joda-time:2.4'
  compile 'joda-time:joda-time:2.4'
  compile 'joda-time:joda-time:2.2'
}

Answer 4

All of these solutions suffer from one of two problems. Either the solution isn't perfectly accurate due to rounding errors, leap days and seconds, etc. or you end up looping over the number of days in between your two unknown dates.

This solution solves the first problem, and improves the second by a factor of roughly 365, better if you know what your max range is.

/**
 * @param thisDate
 * @param thatDate
 * @param maxDays
 *            set to -1 to not set a max
 * @returns number of days covered between thisDate and thatDate, inclusive, i.e., counting both
 *          thisDate and thatDate as an entire day. Will short out if the number of days exceeds
 *          or meets maxDays
 */
public static int daysCoveredByDates(Date thisDate, Date thatDate, int maxDays) {
    //Check inputs
    if (thisDate == null || thatDate == null) {
        return -1;
    }

    //Set calendar objects
    Calendar startCal = Calendar.getInstance();
    Calendar endCal = Calendar.getInstance();
    if (thisDate.before(thatDate)) {
        startCal.setTime(thisDate);
        endCal.setTime(thatDate);
    }
    else {
        startCal.setTime(thatDate);
        endCal.setTime(thisDate);
    }

    //Get years and dates of our times.
    int startYear = startCal.get(Calendar.YEAR);
    int endYear = endCal.get(Calendar.YEAR);
    int startDay = startCal.get(Calendar.DAY_OF_YEAR);
    int endDay = endCal.get(Calendar.DAY_OF_YEAR);

    //Calculate the number of days between dates.  Add up each year going by until we catch up to endDate.
    while (startYear < endYear && maxDays >= 0 && endDay - startDay + 1 < maxDays) {
        endDay += startCal.getActualMaximum(Calendar.DAY_OF_YEAR); //adds the number of days in the year startDate is currently in
        ++startYear;
        startCal.set(Calendar.YEAR, startYear); //reup the year
    }
    int days = endDay - startDay + 1;

    //Honor the maximum, if set
    if (maxDays >= 0) {
        days = Math.min(days, maxDays);
    }
    return days;
}

If you need days between dates (uninclusive of the latter date), just get rid of the + 1 when you see endDay - startDay + 1.

Answer 5

One another way:

public static int numberOfDaysBetweenDates(Calendar fromDay, Calendar toDay) {
        fromDay = calendarStartOfDay(fromDay);
        toDay = calendarStartOfDay(toDay);
        long from = fromDay.getTimeInMillis();
        long to = toDay.getTimeInMillis();
        return (int) TimeUnit.MILLISECONDS.toDays(to - from);
    }

Answer 6

Use jodatime API

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

where 'start' and 'end' are your DateTime objects. To parse your date Strings into DateTime objects use the parseDateTime method

There is also an android specific JodaTime library.