Date difference from current date in java

Question

I am developing an application in JAVA swing, in that I wanted the date difference from current date like if today is 16/04/2013 then it should return 15/04/2013. I have tried the following code:

Calendar cal = new GregorianCalendar();
Calendar cal2 = new GregorianCalendar();
cal.roll(Calendar.DAY_OF_YEAR, -1);
//if within the first 30 days, need to roll the year as well
if(cal.after(cal2)){
     cal.roll(Calendar.YEAR, -1);
}
System.out.println("Year " + cal.get(Calendar.YEAR));
System.out.println("Month " + cal.get(Calendar.MONTH));
System.out.println("Day " + cal.get(Calendar.DAY_OF_MONTH));

In this code I was expecting to get one day back date. But instead I am getting one month back date. Ex. if today is 16/04/2013, the expected output is 15/04/2013, but I am getting 15/03/2013 ( one month one day back) as an output.

Are you obliged to use Calendar or would it be acceptable to use JodaTime? — fvu, Apr 16 '13 at 13:45
This has been answered before: http://stackoverflow.com/questions/3299972/difference-in-days-between-two-dates-in-java — user1697575, Apr 16 '13 at 13:47

Evgeniy Dorofeev · Answer 1 · 2013-04-16T14:34:14.863

5

You dont need any manual manipulations, Calendar will do all necessary date arithmetic automatically, simply do this

    Calendar cal = new GregorianCalendar();
    cal.add(Calendar.DATE, -1);

Note that months in Calendar start from 0 so April is 3

edited Apr 16 '13 at 14:34

answered Apr 16 '13 at 13:50

Evgeniy Dorofeev

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`Calendar cal = new GregorianCalendar(); cal.add(Calendar.DATE, -1); System.out.println("Year " + cal.get(Calendar.YEAR)); System.out.println("Month " + cal.get(Calendar.MONTH)); System.out.println("Day " + cal.get(Calendar.DAY_OF_MONTH));` this is what output im getting `Year 2013 Month 3 Day 15` – Jayesh_naik Apr 16 '13 at 14:04
I added output to my test, it's 15 Apr 2013 – Evgeniy Dorofeev Apr 16 '13 at 14:04
Ah, got you, 3 is Apr, months start from 0 in Calendar – Evgeniy Dorofeev Apr 16 '13 at 14:07

score 2 · Answer 2 · answered Apr 16 '13 at 14:21

That's a classic example why java.util.Date implementation sucks: Months numeration starts in zero:

0-> January
1-> February
2-> March
3-> April.

What you mean:

new Date(10,1,2013) //10th of January of 2013

What you get: 10th of February of 3983 (1970+2013)

Date difference from current date in java

2 Answers2