What is purpose of locale setting in Java java.util.Calendar?

Question

I am obtaining information (such as number of a day in week, month, year etc) about particular date in Java via java.util.Calendar. Is there some reason to set locale for calendar object in my situation? I am asking beacuse:

System.out.println(cal.get(Calendar.DAY_OF_WEEK));

returns for today (Sunday) always number 1 but in our locale (cs_CZ) it should be 7.

Locale locale = new Locale("cs", "CZ");
TimeZone tz = TimeZone.getTimeZone("Europe/Prague");

Calendar cal = GregorianCalendar.getInstance(tz, locale);
cal.setTime(new Date());

// returns => 1 (but I expected 7)
System.out.println(cal.get(Calendar.DAY_OF_WEEK)); 
// returns => 3 - it's OK
System.out.println(cal.get(Calendar.DAY_OF_MONTH));

EDIT: I can hadle with 1 for Sunday, but I must be sure this is unchanging behaviour regardless to used Locale or TimeZone.

Answer 1

Locale do will affect the first day of week. However, the day values are constants, SUNDAY is always 1. You can check this link . The get() method just returns the correct field value (If it returns 7 then it's wrong -- 7 is SATURDAY , not the current day).

But you can call getFirstDayOfWeek() and it returns 2 ( MONDAY ). I think this is what you need. You can take use of these two methods to reach your goal.

System.out.println((cal.get(Calendar.DAY_OF_WEEK) - cal.getFirstDayOfWeek() + 7) % 7 + 1);

The above statements returns 7.

Answer 2

Finally I used Joda Time library:

DateTime dt = new DateTime(new Date());
int dayOfWeek = dt.getDayOfWeek();

and it returns 7 for today (Sunday).