Number of months between two dates in current year

Question

I need to calculate in Java the number of months between two Date objects, but only for the ones which are in the given year.

For example:

01.04.2013 - 30.07.2013, year=2013 => result=4

01.10.2013 - 30.02.2014, year=2013 => result=3

For the second example the result is 3, because only October, November and December are in the given year, 2013. The rest of the months are in 2014.

01.10.2012 - 30.02.2014, year=2013 => result=12

I have this code, but id doesn't work for the following case 01.04.2013 - 30.07.2013, year=2012 => result=0

        Calendar startCalendar = new GregorianCalendar();
        startCalendar.setTime(c.getStartDate());
        Calendar endCalendar = new GregorianCalendar();
        endCalendar.setTime(c.getEndDate());


        Calendar calculatedStartDate = new GregorianCalendar();
        Calendar calculatedEndDate = new GregorianCalendar();

        if (startCalendar.get(Calendar.YEAR) < year) {
            calculatedStartDate.setTime(new GregorianCalendar(year, Calendar.JANUARY, 1).getTime());
        }
        else {
            calculatedStartDate.setTime(c.getStartDate());
        }

        if (endCalendar.get(Calendar.YEAR) > year) {
            calculatedEndDate.setTime(new GregorianCalendar(year, Calendar.DECEMBER, 31).getTime());
        }
        else {
            calculatedEndDate.setTime(c.getEndDate());
        }

        int diffMonth = calculatedEndDate.get(Calendar.MONTH) - calculatedStartDate.get(Calendar.MONTH);
        return diffMonth + 1;

show what you done. we can help you.. if you found any issues? We are not here to do your homework. — Dilip Kumar
Actually, some of us are here to do your homework. Asking to solve homework questions isn't forbidden. — Mark
This is not even a homework, I don't know who would even give such problem as homework. I added the code I've got, removing the business context. Still don't get why people who don't know the answer rate this question as negative. — Soreena
Just to put my 2 cents in: the biggest time period which is regular is a week (just like an hour, a minute, a second). The month is the smallest time period which is irregular. Whenever i have to measure time 'distances' (e.g. in countdowns on my site) i like to do it using weeks exactly because of this. When you say X months you don't know exactly how many weeks, but when you say X weeks you know exactly how many days that is (maybe this doesn't help you, just wanted to point it out :) — Sandman

JustAnotherDeveloper JustAnotherDeveloper · Accepted Answer · 2015-04-29T20:24:33

Check if the second date is of the same year of first; then if this condition is false, set the second date with "31/12/year" and calculate the number of months.

For example:

first date: 31/4/2014
second date: 28/7/2014
2014 > 2014: false, so
    7-4 = 3 + 1 = 4 months

first date: 31/4/2014
second date: 28/7/2015
2015 > 2014: true, so
    second date = 31/12/2014
    12-4 = 8 + 1 = 9 months

Number of months between two dates in current year

1 Answers