Date difference in months

Question

How can I find the difference between two dates in months?
I assume I can't do this:
Date firstDate = 4/1/2000;
Date secondDate = 6/1/2002;
int monDiff = secondDate - firstDate;
Also is it better to use java date or sql date?
thx.

Answer 1

Here is a method that will compute the difference in years, months, and days. It's a bit more tricky that the previous post suggested when you take into account the day of the month. I'm not sure but I think that when you add a month to a date as in the suggested code you may have odd things happen when you go from Jan 31 to Feb to March since Feb may only have 28 days in it.
     * Compute the difference between two dates in years, months, and days.
     * The result is returned in a concatenated integer value of the form
     * ymmdd. So the difference between Apr 20, 2003 and Apr 15, 2025 would
     * be 211126 (21 years, 11 months, and 26 days) since 21 years and
     * 11 months gets you to May 20 2025, there are 31 days in May of 2025,
     * and it takes 25 days to go from May 20 2025 to April 15 2025! To split
     * the values off,
     * #years = return value / 10000,
     * #months = return value % 10000 / 100
     * #days = return value % 100.
     * This method will return a negative value if the 'from' value is after the
     * 'to' value (i.e. getDiff( from, to) = -getDiff( to, from )).
     * @param pFrom The time to compute the difference from.
     * @param pTo Date The time to compute the difference to.
     * @return int The differenct in the two dates in the form ymmdd.
    public static int getDiff( java.util.Date pFrom, java.util.Date pTo )
        int lMultiplier = 1;
        if ( pFrom.after( pTo ) );
            lMultiplier = -1;
            java.util.Date pTemp = pTo;
            pTo = pFrom;
            pFrom = pTemp;
        Calendar lFrom = new GregorianCalendar();
        lFrom.setTime( pFrom );
        Calendar lTo = new GregorianCalendar();
        lTo.setTime( pTo );
        int lFromYear = lFrom.get( Calendar.YEAR );
        int lFromMonth = lFrom.get( Calendar.MONTH );
        int lFromDay = lFrom.get( Calendar.DAY_OF_MONTH );
        int lToYear = lTo.get( Calendar.YEAR );
        int lToMonth = lTo.get( Calendar.MONTH );
        int lToDay = lTo.get( Calendar.DAY_OF_MONTH );
        int lYearDiff = lToYear - lFromYear;
        int lMonthDiff = lToMonth - lFromMonth;
        int lDayDiff = lToDay - lFromDay;
        if ( lDayDiff < 0 )
            lMonthDiff--;
            Calendar lTemp = new GregorianCalendar();
            lTemp.setTime( pTo );
            lTemp.add( lTemp.MONTH, -1 );
            lDayDiff = lTemp.getActualMaximum( lTemp.DAY_OF_MONTH ) + lDayDiff;
        if ( lMonthDiff < 0 )
            lYearDiff--;
            lMonthDiff = 12 + lMonthDiff;
        return lMultiplier * ( lYearDiff * 10000 + lMonthDiff * 100 + lDayDiff );
    }