Set Calendar to next Thursday

Question

I'm developing an app in Android which have a service that must be executed every Thursday and Sunday at 22:00

What I do need, is to set a Calendar to that day and time. However, I'm not sure about how to do it.

Calendar calendar = Calendar.getInstance();

This is giving me a calendar with the current date and time.

I know I can add days, minutes, hours, etc. But, is there any way to directly setNext("thursday")?

I don't want to do many maths there. I mean I'm looking for an answer which doesn't need to calculate how many minutes/hours/days are left till next thursday.

Thank you!!

The calendar api is horrendous for doing what you want. It is awful. — Zavior, Sep 27 '13 at 13:26
With a lot of pain and time. Certainly not without a lot of maths. — Zavior, Sep 27 '13 at 13:37
@Zavior I've found an answer. Not many maths and not much time :) — Reinherd, Sep 27 '13 at 13:52

score 3 · Accepted Answer · answered Sep 27 '13 at 14:12

I've found the below solution simpler, a bit more portable as it doesn't involve much math. Once you set it to Thursday I believe you can use thesetTime() method on the calendar object to set it to 22:00.

//dayOfWeekToSet is a constant from the Calendar class
//c is the calendar instance
public static void SetToNextDayOfWeek(int dayOfWeekToSet, Calendar c){
    int currentDayOfWeek = c.get(Calendar.DAY_OF_WEEK);
            //add 1 day to the current day until we get to the day we want
    while(currentDayOfWeek != dayOfWeekToSet){
        c.add(Calendar.DAY_OF_WEEK, 1);
        currentDayOfWeek = c.get(Calendar.DAY_OF_WEEK);
    }
}

  //usage:
  Calendar c = Calendar.getInstance();
  System.out.println(c.getTime());
  SetToNextDayOfWeek(Calendar.THURSDAY,c);
    System.out.println(c.getTime());

Wow. Totally true, so easy to understand and with 0 maths. – Reinherd Sep 27 '13 at 14:37 — Reinherd, Sep 27 '13 at 14:37

Reinherd · Answer 2 · 2013-09-27T14:01:58.123

1

Not many maths, solved this, so clean:

    int weekday = calendar.get(Calendar.DAY_OF_WEEK);  
    if (weekday!=Calendar.THURSDAY){//if we're not in thursday
        //we calculate how many days till thursday
        //days = The limit of the week (its saturday) minus the actual day of the week, plus how many days till desired day (5: sunday, mon, tue, wed, thur). Modulus of it.
        int days = (Calendar.SATURDAY - weekday + 5) % 7; 
        calendar.add(Calendar.DAY_OF_YEAR, days);
    }
    //now we just set hour to 22.00 and done.

Credit to: http://www.coderanch.com/t/385117/java/java/date-Monday

I just adapted and explained the code.

edited Sep 27 '13 at 14:01

answered Sep 27 '13 at 13:51

Reinherd

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I arrived at almost the same result, albeit with a messier solution using Calenders set-method. Yours is much clearer solution :P – Zavior Sep 27 '13 at 13:53
Nice solution. I used to friday. – Edi Sep 28 '21 at 13:18

score 0 · Answer 3 · edited Oct 17 '17 at 11:45

0

Try this?

c.add(c.DAY_OF_YEAR, -7);

or

c.add(c.DAY_OF_YEAR, +7);

edited Oct 17 '17 at 11:45

António Almeida

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answered Sep 27 '13 at 13:33

Amod Gokhale

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This is adding 7 days to the actual day. Not what I want, as if I run this on a Monaday, it will be executed again next monday. – Reinherd Sep 27 '13 at 13:36

score -1 · Answer 4 · answered Apr 24 '19 at 05:34

-1

calendar.set(Calendar.DAY_OF_WEEK, Calendar.THURSDAY);

answered Apr 24 '19 at 05:34

Robert Goodrick

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Set Calendar to next Thursday

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