Worldwide DST
zones change very often and there’s no central authority coordinating it.
A country, or in some cases even a city, can decide if and how to apply or revoke it.
Everytime it happens, the change is recorded in the IANA Time Zone Database
, and the update will be rolled out in a future release of the JRE.
We can force the modified Time Zone data containing the new DST settings into the JRE through Java Time Zone Updater Tool
,