Difference between 2 dates in Months rounded up to the nearest whole month

                       Calendar old = Calendar.getInstance();
                  old.setTime( date1 );

                  // set the calendar object representing the current date //
                  Calendar now = Calendar.getInstance();
                  now.setTime( date2 );

                  // get the difference between the 2 dates in milliseconds //
                  long difference = now.getTimeInMillis() - old.getTimeInMillis();

                  // set the calendar object representing the difference //
                  Calendar diff = Calendar.getInstance();
                  diff.setTimeInMillis(difference);

                  // print the difference //
                  System.out.println(diff.get(Calendar.MONTH) + " months" ) ;

So you mean given date1 and date2, get the difference expressed in number of months.
+ date1 has always 00:00:00 as time and date2 always has 23:59:59 as time.
Right?

My comment assumes you have date1 and date2 which are both java.util.Date objects :-)

Hi Tim, quite close.
But does that "round to the nearest month"?
I don't think so.

zznyx,

stated far more succinctly.

TimYates,

would your code handle month with 31 days in the way it would handle february (i.e. 1st feb to 2nd of Mar = 2 months; 1st of Mar to 31st of Mar = 1month)

How can you round to the nearest month?

How many days is 0.5 months?  Surely it depends on the number of days in a month?

And the question says:

> rounded to the nearest whole month

Which I took to mean "round down" ;-)

Sorry Tim,

Meant to say part months are counted as whole months.

Hmmm...actually...that code needs a bit of thought ;-)

it will give you a difference, but it will be a bit odd...  How many days are you taking as a month?  4 weeks, 31, 28, what?

So you want

date1=x-may-2004 00:00:00
date2=y-jun-2004 23:59:00

to return 1 if y <= x
and to return 2 if y > x

Right?

Can't it be done like this:

1) int result = 0;
2) Start by putting date1 in calendar.
3) Add one month and result++;
4) If the result is > date2
       return result;
    else
       goto 3) again

Like this:

int result = 0;
Calendar cal = Calendar.getInstance();
cal.setTime( date1 );
while ( cal.getTime().before( date2 ) ) {
     result++;
     cal.add(Calendar.MONTH, 1);
}
return result;

(Didn't try it yet)

import java.util.* ;
import java.text.* ;

public class DateTest
{
  public static void doDates( Date date1, Date date2 )
  {
    Calendar old = Calendar.getInstance() ;
    old.setTime( date1 ) ;

    // set the calendar object representing the current date //
    Calendar now = Calendar.getInstance() ;
    now.setTime( date2 ) ;

    int ret = 0 ;
    while( old.before( now ) )
    {
      old.add( Calendar.MONTH, 1 ) ;
      ret++ ;
    }

    System.out.println( ret + " months" ) ;
  }

  public static void main( String[] args )
  {
    try
    {
      SimpleDateFormat sdf = new SimpleDateFormat( "dd/MM/yyyy" ) ;
      doDates( sdf.parse( "01/02/2004" ), sdf.parse( "02/03/2004" ) ) ;
    }
    catch( ParseException ex )
    {
    }
  }
}

LOL

Soz zzynx...

great minds think alike....and I typed too much... ;-)

>> great minds think alike....and I typed too much... ;-)
:°)

It works, but it seems that the time of date2 must be set to 00:00:00 too, to get the correct results:

        SimpleDateFormat fmt = new SimpleDateFormat("yyyyMMdd HHmmss");
        Date date1 = null, date2 = null;
        try {
            date1 = fmt.parse("20040201 000000");        // <<<<<<<<<<<<< Here you can put in the dates you want to test
            date2 = fmt.parse("20040301 235959");        // <<<<<<<<<<<<< Here you can put in the dates you want to test
        } catch (ParseException ex) { }
       
        // date2 needs some tweaking
        Calendar calTmp = Calendar.getInstance();
        calTmp.setTime(date2);
        calTmp.set(Calendar.HOUR_OF_DAY, 0);
        calTmp.set(Calendar.MINUTE, 0);
        calTmp.set(Calendar.SECOND, 0);
        calTmp.set(Calendar.MILLISECOND, 0);
        date2 = calTmp.getTime();
       
        int result = 0;
        Calendar cal = Calendar.getInstance();
        cal.setTime( date1 );
        while ( !cal.getTime().after( date2 ) ) {
            result++;
            cal.add(Calendar.MONTH, 1);
        }
        System.out.println(result);

1-feb => 20-feb : 1
1-feb => 1-mar : 2
1-feb => 2-mar : 2
1-feb => 31-mar : 2
1-feb => 1-apr : 3

Mmmm. °blush°

I retested and it seem to give the expected result without that date2 tweaking too.
So, it looks like you can remove these lines again:

        // date2 needs some tweaking
        Calendar calTmp = Calendar.getInstance();
        calTmp.setTime(date2);
        calTmp.set(Calendar.HOUR_OF_DAY, 0);
        calTmp.set(Calendar.MINUTE, 0);
        calTmp.set(Calendar.SECOND, 0);
        calTmp.set(Calendar.MILLISECOND, 0);
        date2 = calTmp.getTime();

*giggle*

;-)

>> *giggle*

Look to your other Q's, you naughty boy!
;°D

zzynx,
that's the way I want it.

thanks (sorry about the delay responding. users wanted a demo).

Great!
Thanks for accepting

(Although for the people after us reading this thread it would've been better to mark another comment as accepted answer)