Calendar is not working properly

Question

My conversion from timestamp to Calendar was done, apparently successfully, as the data presented appeared correct except the day of the week.

data=(java.util.Gregoriancalendar) java.util.Gregoriancalendar[time=-125784706799416,areFieldsSet=true,areAllFieldsSet=true,lenient=true,zone=sun.util.calendar.ZoneInfo[id="America/Sao_Paulo",offset=-10800000,dstSavings=3600000,useDaylight=true,transitions=129,lastRule=java.util.SimpleTimeZone[id=America/Sao_Paulo,offset=-10800000,dstSavings=3600000,useDaylight=true,startYear=0,startMode=3,startMonth=9,startDay=15,startDayOfWeek=1,startTime=0,startTimeMode=0,endMode=3,endMonth=1,endDay=15,endDayOfWeek=1,endTime=0,endTimeMode=0]],firstDayOfWeek=1,minimalDaysInFirstWeek=1,ERA=0,YEAR=2017,MONTH=1,WEEK_OF_YEAR=6,WEEK_OF_MONTH=1,DAY_OF_MONTH=2,DAY_OF_YEAR=33,DAY_OF_WEEK=2,DAY_OF_WEEK_IN_MONTH=1,AM_PM=0,HOUR=8,HOUR_OF_DAY=8,MINUTE=40,SECOND=0,MILLISECOND=584,ZONE_OFFSET=-10800000,DST_OFFSET=0]

Note the following values:
YEAR: 2017 (OK)
MONTH: 1 (OK - Starts at 0, so we’re talking about February)
DAY_OF_YEAR: 33 (OK - since we have the 2nd of February)
DAY_OF_WEEK: 2 (WRONG, should be 5)

The following lines have been executed:

Calendar data = Calendar.getInstance();
data.set(0, 0, 0, 0, 0, 0);
data.setTime(arrAAM.get(i).getRegistroAulaAvulsa().getDataInicio());

NOTE: Remember that I tried in with milliseconds (setTimeInMillis).

Answer 1

I tested the following program:

import java.util.Calendar;
import java.util.TimeZone;

public class TesteCalendar {
    public static void main(String[] args) {
        Calendar data = Calendar.getInstance();
        data.set(2017, Calendar.FEBRUARY, 2, 8, 40, 0);
        data.set(Calendar.MILLISECOND, 584);
        data.setTimeZone(TimeZone.getTimeZone("America/Sao_Paulo"));
        System.out.println(data.get(Calendar.DAY_OF_WEEK));
        System.out.println(data);
    }
}

Here’s his way out:

5 java.util.Gregoriancalendar[time=1486032000584,areFieldsSet=true,areAllFieldsSet=true,lenient=true,zone=sun.util.calendar.ZoneInfo[id="America/Sao_Paulo",offset=-10800000,dstSavings=3600000,useDaylight=true,transitions=129,lastRule=java.util.SimpleTimeZone[id=America/Sao_Paulo,offset=-10800000,dstSavings=3600000,useDaylight=true,startYear=0,startMode=3,startMonth=9,startDay=15,startDayOfWeek=1,startTime=0,startTimeMode=0,endMode=3,endMonth=1,endDay=15,endDayOfWeek=1,endTime=0,endTimeMode=0]],firstDayOfWeek=1,minimalDaysInFirstWeek=1,ERA=1,YEAR=2017,MONTH=1,WEEK_OF_YEAR=5,WEEK_OF_MONTH=1,DAY_OF_MONTH=2,DAY_OF_YEAR=33,DAY_OF_WEEK=5,DAY_OF_WEEK_IN_MONTH=1,AM_PM=0,HOUR=8,HOUR_OF_DAY=8,MINUTE=40,SECOND=0,MILLISECOND=584,ZONE_OFFSET=-10800000,DST_OFFSET=3600000]

However, a detail attentive me, on his exit appears time=-125784706799416 and on my way out time=1486032000584. Looking closer, yours is with ERA=0 and mine with ERA=1. Going in the javadoc, I see that BC is 0 and AD is 1. Meaning yours is in BC and my in AD. Here’s what it is BC in accordance with the javadoc:

Value of the ERA field indicating the period before the common era (before Christ), also known as BCE. The Sequence of years at the Transition from BC to AD is ..., 2 BC, 1 BC, 1 AD, 2 AD,...

I’ll just emphasize that part:

before Christ

That is, you put 2 February of the year 2017 before Christ!

The solution then, is to add this:

data.set(Calendar.ERA, GregorianCalendar.AD);