[java] Subtract two dates in Java

Possible Duplicate:
Calculating the Difference Between Two Java Date Instances

I know this might be a duplicate thread. But I am trying to figure out a way to compute the difference between two dates. From jquery the date string is in the format 'yyyy-mm-dd'. I read this as a String and converted to java Date like this

Date d1 = new SimpleDateFormat("yyyy-M-dd").parse((String) request.getParameter(date1));
Date d2 = new SimpleDateFormat("yyyy-M-dd").parse((String) request.getParameter(date2));

I want to compute the difference in the number of days between these two dates.

Note: I cannot use third party API's as those need to reviewed.

Assuming that you're constrained to using Date, you can do the following:

Date diff = new Date(d2.getTime() - d1.getTime());

Here you're computing the differences in milliseconds since the "epoch", and creating a new Date object at an offset from the epoch. Like others have said: the answers in the duplicate question are probably better alternatives (if you aren't tied down to Date).

Date d1 = new SimpleDateFormat("yyyy-M-dd").parse((String) request.
            getParameter(date1));
Date d2 = new SimpleDateFormat("yyyy-M-dd").parse((String) request.
            getParameter(date2));

long diff = d2.getTime() - d1.getTime();

System.out.println("Difference between  " + d1 + " and "+ d2+" is "
        + (diff / (1000 * 60 * 60 * 24)) + " days.");