Java: what is your default timezone?

cat MyTimezone.java

import java.util.TimeZone;

public class  MyTimezone {
    public static void main(String[] args) throws Exception {
        TimeZone timeZone = TimeZone.getDefault();
        System.out.println(timeZone);
    }
}

javac MyTimezone.java

java MyTimezone

on one machine I have:

sun.util.calendar.ZoneInfo[id="Europe/Zurich",offset=3600000,dstSavings=3600000,useDaylight=true,
transitions=119,lastRule=java.util.SimpleTimeZone[id=Europe/Zurich,offset=3600000,dstSavings=3600000,
useDaylight=true,startYear=0,startMode=2,startMonth=2,startDay=-1,startDayOfWeek=1,startTime=3600000,startTimeMode=2,endMode=2,
endMonth=9,endDay=-1,endDayOfWeek=1,endTime=3600000,endTimeMode=2]]

on another machine I have:

sun.util.calendar.ZoneInfo[id="Europe/Vaduz",offset=3600000,dstSavings=3600000,useDaylight=true,
transitions=119,lastRule=java.util.SimpleTimeZone[id=Europe/Vaduz,offset=3600000,dstSavings=3600000,
useDaylight=true,startYear=0,startMode=2,startMonth=2,startDay=-1,startDayOfWeek=1,startTime=3600000,startTimeMode=2,endMode=2,
endMonth=9,endDay=-1,endDayOfWeek=1,endTime=3600000,endTimeMode=2]]

The second machine has timezone "Europe/Vaduz", and the Oracle DB doesn't recognize it:

SELECT * FROM V$TIMEZONE_NAMES where TZNAME = 'Europe/Vaduz';

nothing!

This explains why your JVM might get in trouble with the Oracle DB and you have to set explicitly the timezone yourself...

See also http://www.javamonamour.org/2014/11/ora-01882-timezone-region-not-found.html

Funnily:

diff /usr/share/zoneinfo/Europe/Vaduz /etc/localtime

diff /usr/share/zoneinfo/Europe/Zurich /etc/localtime

these 2 files are identical.

How does Java determine its default timezone from the Linux machine it's running on?

on RHEL, use redhat-config-date system-config-time timeconfig tzselect