FULL PRODUCT VERSION :
java version "1.7.0_21"
Java(TM) SE Runtime Environment (build 1.7.0_21-b12)
Java HotSpot(TM) 64-Bit Server VM (build 23.21-b01, mixed mode)

ADDITIONAL OS VERSION INFORMATION :
Tested on ubuntu/linux 10.04 and earlier
macosx 10.6 and earlier

A DESCRIPTION OF THE PROBLEM :
The locale es_DO from your implementation, produces a DateFormat as month, day and year. This is not the date format use in the Dominican Republic it is day, month and year.

ADDITIONAL REGRESSION INFORMATION:
It seems that this is an old bug.

STEPS TO FOLLOW TO REPRODUCE THE PROBLEM :
Write a code:

Locale esDO = new Locale("es", "DO");
DateFormat format = DateFormat.getDateInstance(DateFormat.SHORT, esDO);
Calendar cal = Calendar.getInstance(esDO);
cal.set(Calendar.DAY_OF_MONTH, 31);
cal.set(Calendar.MONTH, Calendar.MARCH);
cal.set(Calendar.YEAR, 2012);
System.out.println(esDO + " - " + format.format(cal.getTime()));


EXPECTED VERSUS ACTUAL BEHAVIOR :
EXPECTED -
es_DO - 31/03/12
ACTUAL -
es_DO - 03/31/12

ERROR MESSAGES/STACK TRACES THAT OCCUR :
No error messages

REPRODUCIBILITY :
This bug can be reproduced always.

---------- BEGIN SOURCE ----------
import java.text.DateFormat;
import java.util.Calendar;
import java.util.Date;
import java.util.Locale;

public class ATest {
public static void main(String[] args) throws Exception {
Locale esDO = new Locale("es", "DO");
DateFormat format = DateFormat.getDateInstance(DateFormat.SHORT, esDO);
Calendar cal = Calendar.getInstance(esDO);
cal.set(Calendar.DAY_OF_MONTH, 31);
cal.set(Calendar.MONTH, Calendar.MARCH);
cal.set(Calendar.YEAR, 2012);
System.out.println(esDO + " - " + format.format(cal.getTime()));
}
}

---------- END SOURCE ----------