The OP answered this question to change the default timezone for a single instance of a running JVM, set the user.timezone
system property:
java -Duser.timezone=GMT ... <main-class>
If you need to set specific time zones when retrieving Date/Time/Timestamp objects from a database ResultSet
, use the second form of the getXXX
methods that takes a Calendar
object:
Calendar tzCal = Calendar.getInstance(TimeZone.getTimeZone("GMT"));
ResultSet rs = ...;
while (rs.next()) {
Date dateValue = rs.getDate("DateColumn", tzCal);
// Other fields and calculations
}
Or, setting the date in a PreparedStatement:
Calendar tzCal = Calendar.getInstance(TimeZone.getTimeZone("GMT"));
PreparedStatement ps = conn.createPreparedStatement("update ...");
ps.setDate("DateColumn", dateValue, tzCal);
// Other assignments
ps.executeUpdate();
These will ensure that the value stored in the database is consistent when the database column does not keep timezone information.
The java.util.Date
and java.sql.Date
classes store the actual time (milliseconds) in UTC. To format these on output to another timezone, use SimpleDateFormat
. You can also associate a timezone with the value using a Calendar object:
TimeZone tz = TimeZone.getTimeZone("<local-time-zone>");
//...
Date dateValue = rs.getDate("DateColumn");
Calendar calValue = Calendar.getInstance(tz);
calValue.setTime(dateValue);
Usefull Reference
https://docs.oracle.com/javase/9/troubleshoot/time-zone-settings-jre.htm#JSTGD377
https://confluence.atlassian.com/kb/setting-the-timezone-for-the-java-environment-841187402.html