Name: avC70361 Date: 07/06/98



  java.util.SimpleTimeZone.getOffset works wrong for some dates. inDaylightTime
for that date returns true, but getOffset returns offset which is not equal to
GMT offset + DST saving offset.

Here is a test demonstrating the bug.
---------------
import java.util.Calendar;
import java.util.Date;
import java.util.GregorianCalendar;
import java.util.SimpleTimeZone;
import java.util.TimeZone;

public class GetOffsetTest {

  public static void main(String args[]) {
    SimpleTimeZone tz = new SimpleTimeZone(
      60 * 60 * 1000, "stz",
      Calendar.JANUARY, 1, 0, 0, /* DST start day: January, 1, 0:00 */
      Calendar.APRIL, 1, 0, 0, /* DST end day: April, 1, 0:00 */
      60 * 60 * 1000
    );

    Calendar calendar = new GregorianCalendar(TimeZone.getTimeZone("GMT"));

TimeZone.setDefault(TimeZone.getTimeZone("GMT"));

    // setting a date just after end rule using GMT zone
    calendar.clear();
    calendar.set(Calendar.ERA, GregorianCalendar.AD);
    calendar.set(Calendar.YEAR, 1998);
    calendar.set(Calendar.MONTH, Calendar.MARCH);
    calendar.set(Calendar.DATE, 31);
    calendar.set(Calendar.HOUR, 22);
    calendar.set(Calendar.MINUTE, 1);

    Date date = calendar.getTime();

    int expectedOffset;

    boolean inDST = tz.inDaylightTime(date);

    if (inDST) {
      expectedOffset = tz.getRawOffset() + tz.getDSTSavings();
    } else {
      expectedOffset = tz.getRawOffset();
    }

    calendar = new GregorianCalendar(tz);

    calendar.setTime(date);

    int offset = tz.getOffset(
      calendar.get(Calendar.ERA),
      calendar.get(Calendar.YEAR),
      calendar.get(Calendar.MONTH),
      calendar.get(Calendar.DATE),
      calendar.get(Calendar.DAY_OF_WEEK),
      calendar.get(Calendar.HOUR) * 3600000
      + calendar.get(Calendar.MINUTE) * 60000
      + calendar.get(Calendar.SECOND) * 1000
      + calendar.get(Calendar.MILLISECOND)
      -(inDST ? tz.getDSTSavings() : 0) /* we should use standard local time */
    );

    if (offset != expectedOffset) {
      System.out.println(
        "tz = " + tz + "\n" +
        "date = " + date + "\n" +
        "in DST = " + tz.inDaylightTime(date) + "\n" +
        "expected offset = " + expectedOffset + "\n" +
        "Failed. getOffset() returns " + offset
      );
    } else {
      System.out.println("Passed");
    }
  }
}

---------The test output--------
> java GetOffsetTest
tz = java.util.SimpleTimeZone[id=stz,offset=3600000,dstSavings=3600000,useDaylight=true,startYear=0,startMode=1,startMonth=0,startDay=1,startDayOfWeek=0,startTime=0,endMode=1,endMonth=3,endDay=1,endDayOfWeek=0,endTime=0]
date = Tue Mar 31 22:01:00 GMT 1998
in DST = true
expected offset = 7200000
Failed. getOffset() returns 3600000

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