how to get last thursday of month in java

Question

I have to fetch date of last Thursday of month of any year but the problem I'm facing is that for the month of dec'15 last thursday is 31-dec-2015 but I'm getting 24-dec-2015 for the following code:

Date getLastThursday(def month, def year ) {
    Calendar cal = Calendar.getInstance();
    cal.set( year, month,1 )
    cal.add( Calendar.DAY_OF_MONTH, -(cal.get(Calendar.DAY_OF_WEEK )%7+2) );
    return cal.getTime();
}

And also explain me how this line of code internally works?

cal.add(Calendar.DAY_OF_MONTH, -(cal.get(Calendar.DAY_OF_WEEK )%7+2))

Did you take into account the fact that the month is 0-based? December is 11. — Tunaki, Dec 15 '15 at 11:29
Explanation how that code works can be found [here](https://praveenlobo.com/blog/get-last-friday-of-the-month-in-java/). — Praveen Lobo, Aug 07 '18 at 04:49

assylias · Accepted Answer · 2015-12-15T12:09:09.317

10

If you use Java 8+, you can use a temporal adjuster (part of the Java Time API):

int month = 12;
int year = 2015;
LocalDate lastThursday = LocalDate.of(year, month, 1).with(lastInMonth(THURSDAY));
System.out.println("lastThursday = " + lastThursday); //prints 2015-12-31

Note: requires static imports

import static java.time.DayOfWeek.THURSDAY;
import static java.time.temporal.TemporalAdjusters.lastInMonth;

If you can't use the new API, I suspect the problem is in the modulus operation and this should work:

//month should be 0-based, i.e. use 11 for December
static Date getLastThursday(int month, int year) {
  Calendar cal = Calendar.getInstance();
  cal.set(year, month + 1, 1);
  cal.add(Calendar.DAY_OF_MONTH, -((cal.get(Calendar.DAY_OF_WEEK) + 2) % 7));
  if (cal.get(Calendar.MONTH) != month) cal.add(Calendar.DAY_OF_MONTH, -7);
  return cal.getTime();
}

The second if condition is there to make sure we have gone back one month.

edited Dec 15 '15 at 12:09

answered Dec 15 '15 at 11:29

assylias

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I'm using java 7, so please tell me for Gregorian calender. – AMAN KUMAR Dec 15 '15 at 11:38
Hey this will work for dec only. – AMAN KUMAR Dec 15 '15 at 11:58
@user3666156 See my edit - it should be fine now (it works for all dates between 1900 and 2100). – assylias Dec 15 '15 at 12:09
@AMANKUMAR For Java 6 & 7, use the *ThreeTen-Backport* project, with much of the *java.time* functionality back-ported. For earlier Android, see the *ThreeTenABP* project. – Basil Bourque Apr 19 '18 at 04:00

score -1 · Answer 2 · answered Dec 15 '15 at 11:58

-1

Just put your modulus % outside:

cal.add( Calendar.DAY_OF_MONTH, -(cal.get(Calendar.DAY_OF_WEEK )+2)%7 );

if not, you get -8 => 24 december

and use month+1

answered Dec 15 '15 at 11:58

guillaume girod-vitouchkina

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how to get last thursday of month in java

2 Answers2