Java Calendar add issue

Question

I'm having an issue with the Java Calendar add() functionality. The give or take is used to provide a roundabout date for dates to depart on a travel site.

end.add(Calendar.DATE, Integer.parseInt(giveOrTake));

The code is above and the test condition I'm using is to choose 29/07/2012 as the date and 3 days give or take. According to the documentation this should come out as 01/08/2012 but it comes out at 01/07/2012.

I've checked giveOrTake when it's passed to the method and it's fine so I have no idea what is going on. I can hardcode the giveOrTake value and still get the error.

Answer 1

Works for me:

import java.util.*;

public class Test {
    public static void main (String []args) {
        Calendar calendar = Calendar.getInstance();
        calendar.set(2012, Calendar.JULY, 29);
        calendar.add(Calendar.DATE, 3);
        System.out.println(calendar.getTime()); // August 1st
    }
}

My guess is that you've got the month wrong before calling add - note how my call to set above uses 6 as the month, because the call uses 0-based month numbers.

Note that as per my comment on the question, you'd be much better off moving to Joda Time if you can...