Until recently, JVM vendors were lazy to update time zone rules. Since North America DST change in 2007, JVM vendors pay more attention to time zone rule changes and they are now delivering tzdata patch in timely manner.
In reality, many ICU4J clients have to deal both Java and ICU4J TimeZone. Because ICU4J has own time zone rule data, they have to apply tzdata update patch to both JVM and ICU4J.
There are some benefits to have own tzdata in ICU. For example, ICU allows users to access time zone transitions and rules. This features can be implemented in ICU, because ICU has its own tzdata. But, majority of ICU4J users do no need such advanced features. For those users who do not need advanced time zone features would be good enough with Java TimeZone. They would rather prefer to less maintenance effort.
This ticket proposes ICU4J to support Java TimeZone as primary TimeZone implementation in ICU4J. Actual tasks would be -
1. Add a class extending com.ibm.icu.util.TimeZone. Implementation of time zone operation in the new class actually calls methods in java.util.TimeZone.
2. Create a global switch to alter the behavior of com.ibm.icu.util.TimeZone#getTimeZone. The switch may be implemented as a static method in com.ibm.icu.util.TimeZone or external configuration file.