As timezone support in the JRE seems to have become a more sensitive topic in recent years - more and more people want to have the latest timezone data incorporated into their environment in real time. Sun released the tzupdater tool to address such issues. Unfortunately with some timezones changes being taken at very short notice, even this effort is not enough for some java users.

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Here's a quick guide (as promised) on how you can incorporate the latest timezone changes into your JRE :

Go, grab a copy of the latest JDK 7 code. In there you'll find all the tools necessary to build the necessary zi files.

Sun uses the Olson timezone data releases as its guide for timezone rules. Their release versions are in the format of tzdata<year><letter>. The current tzdata rules at time of writing are the tzdata2007i rules. Go grab a copy of these at ftp://elsie.nci.nih.gov/pub/tzdata2007i.tar.gz and extract locally.

Java uses the javazic tool to compile its timezone rules. Unix OSes use the zic (Zone Information Compiler) tool. You need to get a copy of the javazic tool compiled in your workspace before the new zi files can be created...

For those of you new to compiling a JDK 7 workspace - here's what you need (paper and scissors are optional)

A JDK 7 binary - Set your ALT_JDK_IMPORT_PATH variable to here.

A JDK 6 binary - Set your ALT_BOOTDIR variable to here.

A Binary Plugs directory - Set your ALT_BINARY_PLUGS_PATH variable to this. - Download from http://download.java.net/openjdk/jdk7/ - Install it using something like : java -jar jdk-7-ea-plug-b23-solaris-sparc-30_oct_2007.jar

cd to the jdk/make directory and issue a gnumake sanity command.

Be sure and read the README-builds.html file included in the JDK7 source if you've issues with building. Bear in mind that http://sunfreeware.com/ is a good spot to pick up any binaries that may be missing from your system.

Build the JDK sub directory : gnumake all

Once you have a build - you're good to make changes to the tzdata files.

fireball $pwd 
/space/sean/JDK7/openjdk/jdk/make/sun/javazic/tzdata
fireball $cp -r ~/tzdata2007i/* .

Don't forget to change the tzdata version number :

 
fireball $tail -1 VERSION 
tzdata2007i

All set for a compilation of these new tzdata files next :

fireball $pwd 
/space/sean/JDK7/openjdk/jdk/make/sun/javazic/tzdata
fireball $gnumake clean
rm -f  ../../../build/solaris-sparc/tmp/sun/sun.javazic/strip_prop_options
rm -f  ../../../build/solaris-sparc/tmp/sun/sun.javazic/compile_prop_options
rm -f ../../../build/solaris-sparc/tmp/sun/sun.javazic/.classes.list
rm -f -r ../../../build/solaris-sparc/tmp/sun/sun.javazic/obj
rm -f -r ../../../build/solaris-sparc/tmp/sun/sun.javazic/obj_*
rm -f -r ../../../build/solaris-sparc/classes/sun/javazic
rm -f ../../../build/solaris-sparc/tmp/sun/sun.javazic/.classes.list
rm -f -r ../../../build/solaris-sparc/tmp/sun/sun.javazic ../../../build/solaris-sparc/lib/zi 

fireball $gnumake all
rm -f -r ../../../build/solaris-sparc/tmp/sun/sun.javazic/zi
/usr/bin/mkdir -p ../../../build/solaris-sparc/tmp/sun/sun.javazic/zi
rm -f ../../../build/solaris-sparc/tmp/sun/sun.javazic/zi/ZoneInfoMappings
/space/sean/jdk/jdk1.6.0_03//bin/java  -client -Xmx896m -Xms128m -XX:PermSize=32m
 -XX:MaxPermSize=160m -jar ../../../build/solaris-sparc/btjars/javazic.jar -V "`/usr/bin/grep '^tzdata' 
./tzdata/VERSION`" -d../../../build/solaris-sparc/tmp/sun/sun.javazic/zi ./tzdata/africa ./tzdata/antarctica 
./tzdata/asia ./tzdata/australasia ./tzdata/europe ./tzdata/northamerica ./tzdata/pacificnew 
./tzdata/southamerica ./tzdata/backward ./tzdata/etcetera ./tzdata/solar87 
 ./tzdata/solar88 ./tzdata/solar89 ./tzdata/systemv ./tzdata_jdk/gmt ./tzdata_jdk/jdk11_backward
rm -f -r ../../../build/solaris-sparc/lib/zi
/usr/bin/mkdir -p ../../../build/solaris-sparc/lib/zi
rm -f ../../../build/solaris-sparc/lib/zi/ZoneInfoMappings
/usr/bin/cp -r ../../../build/solaris-sparc/tmp/sun/sun.javazic/zi/* ../../../build/solaris-sparc/lib/zi

Et Voilà! - a new directory full of the latest timezone rules ready for deployment. The new files will work with JDK 7 or earlier JRE releases. - Just replace the jre/lib/zi directory with the newly created one from your workspace. You should ensure that any instance of the JRE being updated is shut down first - otherwise the risk of the JRE continuing to hold references to older timezone data exists.