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  1. JDK
  2. JDK-8061439

Java should handle user defined TimeZone subclass instances supporting historic

    Details

    • Type: Enhancement
    • Status: Closed
    • Priority: P4
    • Resolution: Duplicate
    • Affects Version/s: 8u25
    • Fix Version/s: None
    • Component/s: core-libs
    • Labels:

      Description

      FULL PRODUCT VERSION :


      A DESCRIPTION OF THE PROBLEM :
      You can create a custom time zone implementation class by extending java.util.TimeZone. By the contract, the subclass must implement a few methods:

      abstract int getOffset(int,int,int,int,int,int);
      abstract int getRawOffset();
      abstract boolean inDaylightTime(Date);
      abstract void setRawOffset(int);
      abstract boolean useDaylightTime();

      Although, the interface above do not assume UTC offset or daylight saving amount is not changing time to time, a user can provide an implementation supporting historic UTC offset changes by int getOffset(int,int,int,int,int,int). However, there are two Java implementation problems.

      1. The default implementation of TimeZone#getOffset(long date) does not use the abstract method - int getOffset(int,int,int,int,int,int). Therefore, when a different 'raw' offset was used in the past, or will be used in future, getOffset(long) always returns a result calculated from getRawOffset() and getDSTSavings(). Although a subclass implementation can provide TimeZone#getOffset(long date), the default implementation should use getOffset(int,int,int,int,int,int).

      2. java.util.GregorianCalendar checks if a TimeZone instance is sun.util.calendar.TimZone or not, and if not, the offset field is calculated based on getRawOffset() / getDSTSavings(). Therefore, even a custom TimeZone implementation support different 'raw' offsets in the past or future, current 'raw' offset (getRawOffset()) value is used.


      Use case:

      A user may want to create a custom TimeZone instance from iCalendar VTIMEZONE component. iCalendr VTIMEZONE can support historic time zone rule changes.

      Suggestions:

      1) Add API TimeZone#getRawOffset(long) with the default implementation - return getRawOffset().
      2) Add API TimeZone#getDSTSavings(long) with the default implementation - return getDSTSavings().
      2) Update the default implementation of TimeZone#getOffset(long) to use #getRawOffset(long) #getDSTSavings(long) above along is existing #inDaylightTime(Date).
      3) Gregorian calendar to use #getRawOffset(long) and #getDSTSavings(long), if not ZoneInfo.



      REPRODUCIBILITY :
      This bug can be reproduced always.

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              • Assignee:
                Unassigned
                Reporter:
                webbuggrp Webbug Group
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                • Created:
                  Updated:
                  Resolved: