The number of months between 2 java.util.Date, excluding the day of the month

Question

I want the number of months between 2 java.util.Date , not taking into account the number of days in a month. So I just want to compare the year and month.

Example:

  monthsBetween(new Date(2012,01,28), new Date(2012,02,01)) ---> 1 monthsBetween(new Date(2012,02,27), new Date(2012,02,28)) ---> 0 monthsBetween(new Date(2012,03,28), new Date(2012,07,01)) ---> 4 

I tried this (returns 0, expected 1) using Joda-time:

 private static int monthsBetween(final Date fromDate, final Date toDate) { DateTime date1 = new DateTime().withDate(2012, 1, 20); DateTime date2 = new DateTime().withDate(2012, 2, 13); PeriodType monthDay = PeriodType.yearDayTime().withDaysRemoved(); Period difference = new Period(date1, date2, monthDay); int months = difference.getMonths(); return months; } 

And also this (same results) using Joda-time:

 private static int monthsBetween(final Date fromDate, final Date toDate) { return Months.monthsBetween(new DateTime(fromDate), new DateTime(toDate).getMonths(); } 

How can i do this?

Answer 1

You ask for the number of months in general - this is not the same as saying “ignore part of the day of the month”.

For starters, I would suggest using LocalDate instead of DateTime for calculations. Ideally, do not use java.util.Date at all and take your input as LocalDate to begin with (for example, by parsing the text or where your data comes from.) Set the day of the month to 1 on both dates, and then accept the difference in months :

 private static int monthsBetweenIgnoreDays(LocalDate start, LocalDate end) { start = start.withDayOfMonth(1); end = end.withDayOfMonth(1); return Months.monthsBetween(start, end).getMonths(); } 

Answer 2

This version is based on the JDK:

 public static void main(String[] args) throws Exception { SimpleDateFormat f = new SimpleDateFormat("yyyy-MM-dd"); Date d1 = f.parse("2012-01-01"); Date d2 = f.parse("2012-02-02"); int n = differenceInMonths(d1, d2); System.out.println(n); } private static int differenceInMonths(Date d1, Date d2) { Calendar c1 = Calendar.getInstance(); c1.setTime(d1); Calendar c2 = Calendar.getInstance(); c2.setTime(d2); int diff = 0; if (c2.after(c1)) { while (c2.after(c1)) { c1.add(Calendar.MONTH, 1); if (c2.after(c1)) { diff++; } } } else if (c2.before(c1)) { while (c2.before(c1)) { c1.add(Calendar.MONTH, -1); if (c1.before(c2)) { diff--; } } } return diff; } 

Answer 3

If you have years and months by int value:

 months = (year2-year1)*12 + month2 - month1; 

Be 12 months a year.

Answer 4

I would just get the fields of the year and month of calendar instances, convert the years to months and get the differences.

 private static int monthsBetween(final Date s1, final Date s2) { final Calendar d1 = Calendar.getInstance(); d1.setTime(s1); final Calendar d2 = Calendar.getInstance(); d2.setTime(s2); int diff = (d2.get(Calendar.YEAR) - d1.get(Calendar.YEAR)) * 12 + d2.get(Calendar.MONTH) - d1.get(Calendar.MONTH); return diff; } 

Answer 5

 /** * Gets number of months between two dates. * <p>Months are calculated as following:</p> * <p>After calculating number of months from years and months from two dates, * if there are still any extra days, it will be considered as one more month. * For ex, Months between 2012-01-01 and 2013-02-06 will be 14 as * Total Months = Months from year difference are 12 + Difference between months in dates is 1 * + one month since day 06 in enddate is greater than day 01 in startDate. * </p> * @param startDate * @param endDate * @return */ public static int getMonthsBetweenDates(Date startDate, Date endDate) { if(startDate.getTime() > endDate.getTime()) { Date temp = startDate; startDate = endDate; endDate = temp; } Calendar startCalendar = Calendar.getInstance(); startCalendar.setTime(startDate); Calendar endCalendar = Calendar.getInstance(); endCalendar.setTime(endDate); int yearDiff = endCalendar.get(Calendar.YEAR)- startCalendar.get(Calendar.YEAR); int monthsBetween = endCalendar.get(Calendar.MONTH)-startCalendar.get(Calendar.MONTH) +12*yearDiff; if(endCalendar.get(Calendar.DAY_OF_MONTH) >= startCalendar.get(Calendar.DAY_OF_MONTH)) monthsBetween = monthsBetween + 1; return monthsBetween; } 

Answer 6

He will work in a leap year.

 public static int getNumberOfMonths(Date fromDate, Date toDate) { int monthCount = 0; Calendar cal = Calendar.getInstance(); cal.setTime(fromDate); int c1date = cal.get(Calendar.DATE); int c1month = cal.get(Calendar.MONTH); int c1year = cal.get(Calendar.YEAR); cal.setTime(toDate); int c2date = cal.get(Calendar.DATE); int c2month = cal.get(Calendar.MONTH); int c2year = cal.get(Calendar.YEAR); System.out.println(" c1date:"+c1date+" month:"+c1month+" year:"+c1year); System.out.println(" c2date:"+c2date+" month:"+c2month+" year:"+c2year); GregorianCalendar grCal = new GregorianCalendar(); boolean isLeapYear1 = grCal.isLeapYear(c1year); boolean isLeapYear2 = grCal.isLeapYear(c2year); monthCount = ((c2year - c1year) * 12) + (c2month - c1month); if(isLeapYear2 && c2month == 1 && c2date == 29){ monthCount = monthCount+ ((c1date == 28)?0:1); }else if(isLeapYear1 && c1month == 1 && c1date == 29){ monthCount = monthCount+ ((c2date == 28)?0:1); }else{ monthCount = monthCount+ ((c2date >= c1date)?0:1); } return monthCount; } 

Answer 7

it will give you the difference in months

 (endCal.get(Calendar.YEAR)*12+endCal.get(Calendar.MONTH))-(startCal.get(Calendar.YEAR)*12+startCal.get(Calendar.MONTH))