Finding difference between two dates

Question

In a JSP page I have four sample dates like 01- dec , 15- dec, 30- dec and 15- jan. I need to check whether the date above and current date's difference is 15.

Here is my attempt:

    Calendar calendar = Calendar.getInstance();
    Calendar calendar1 = Calendar.getInstance();
    Calendar calendar2 = Calendar.getInstance();
    Calendar calendar3 = Calendar.getInstance();
    Calendar calendar4 = Calendar.getInstance();

    calendar1.set(2011, 11, 02);
    calendar2.set(2011, 06, 02);
    calendar3.set(2011, 09, 07);
    calendar4.set(2011, 06, 05);

    long milliseconds1 = calendar1.getTimeInMillis();
    long milliseconds2 = calendar.getTimeInMillis();

    long diff = milliseconds2 - milliseconds1;
    long diffDays = diff / (24 * 60 * 60 * 1000);

    if (diffDays <= 15) {
        System.out.println("Fifteen");
    } else {
        System.out.println("No Fifteen");
            }

I've to check the condition for all the four scenarios whether the difference is 15 or not. Putting those calendar instances in a map or an list. I don't know how to do it.

possible duplicate of Calculating difference in dates in Java — Jigar Joshi
– Jigar Joshi, Commented Dec 16, 2010 at 10:51
You should not do calculations like that in JSP. do it in a backing java service bean and expose the values to the JSP. — Sean Patrick Floyd
– Sean Patrick Floyd, Commented Dec 16, 2010 at 10:58
Writing Java code incorrectly in a JSP file doesn't make it a JSP problem, you would have exactly the same problem when doing so in a normal Java class. So I removed the JSP tag. — BalusC
– BalusC, Commented Dec 16, 2010 at 12:47

CoolBeans · Accepted Answer · 2010-12-16 10:52:49Z

1

I would recommend using joda time for this. It also factors the time zone and daylight saving differences. Here is an example of how to get difference of days between 2 dates.

Days d = Days.daysBetween(startDate, endDate);
int days = d.getDays();
if(days==15){
   //do something
}

answered Dec 16, 2010 at 10:52

CoolBeans

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Comments

John · Accepted Answer · 2011-02-13 02:21:27Z

0

With the date4j library :

int days = dt.numDaysFrom(today);

answered Feb 13, 2011 at 2:21

John

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