I actually have both 1.3.1 and 1.4 JDKs installed. I've been trying to upgrade
my code for a couple years now, from 1.3.1 to 1.4. It's actually pretty easy to do (only change throughout all 200 code files was how StringBuffers did indexOf

. Not to mention the change wasn't even necessary).
The only reason I"ve hesitated up to this point is because JavaDoc now ignores/supresses any and all "@" parameters: @param, @author, @return, ... (
why oh why?! 
). But I've been a server-side geek my whole career, and now I want to learn GUI for first time. I also want to take advantage of regular expressions, and basically get with the times. So despite the plethora of "@" documentation being ignored (
why oh why?! 
), I took the leap. At least, in my local version.
Anyhoo, since I don't switch versions willy nilly (seems like more of a headache than what it's worth), I just have my Ant build.xml file clearly documenting the full CLASSPATH for each JDK, located at the top.
When I need to switch versions, I just overwrite the appropriate system environment CLASSPATH and JAVA_HOME variables to the version I want, in addition to a few other steps.
(I'm not really clear how the registry would be involved at all...unless you're manually manipulating the env. variables there, instead of right-clicking on My Computer.)
Here's the actual (more current and helpful than the online version) documentation in my ant file, word-wrapped so this forum thread isn't 18 screens wide

:
Code: Select all
JDK 1.3.1, ANT 1.4
CLASSPATH:
.;C:\files\a_build\classes\production;C:\files\a_build\classes\t
est_and_docs;C:\applications\java_development_kit\lib\tools.jar;
C:\applications\java_ant\lib\ant.jar;C:\applications\java_ant\li
b\xmlParserAPIs.jar;C:\applications\java_ant\lib\xercesImpl.jar;
C:\applications\java_ant\lib\optional.jar;C:\applications\java_d
evelopment_kit\jre\lib\rt.jar;C:\applications\java_servlets\serv
let_with_jsp.jar;C:\applications\mysql\jdbc_driver\mysql-
connector-java-2.0.14\mysql-connector-java-2.0.14-bin.jar
JAVA_HOME: C:\applications\java_development_kit
Ensure z_javadoc_building_blocks\xbn_doclet contains the 1.3
version of the JavaDoc standard doclet, and that all the code
(1) compiles using the current XBN classes, and that the path to
"doclet_class_map.txt" is correct.
In SOBStringBuffer, ensure that the "1.3.1" section is
uncommented, and the "1.4" section is commented.
JDK 1.4, ANT 1.5
The problems I'm having when switching to 1.4 is
that no @param, @exception, @*anything* is displaying in the
JavaDoc output.
CLASSPATH:
.;C:\applications\java_development_kit_1_4\jre\lib\rt.jar;C:\app
lications\java_development_kit\lib\tools.jar;C:\files\a_build\cl
asses\production;C:\files\a_build\classes\test_and_docs;C:\appli
cations\jakarta_ant\lib\ant.jar;C:\applications\jakarta_ant\lib\
xml-
apis.jar;C:\applications\jakarta_ant\lib\xercesImpl.jar;C:\appli
cations\jakarta_ant\lib\optional.jar;C:\applications\java_servle
ts\servlet_with_jsp.jar;C:\applications\mysql\jdbc_driver\mysql-
connector-java-2.0.14\mysql-connector-java-2.0.14-bin.jar
JAVA_HOME: C:\applications\java_development_kit
Ensure z_javadoc_building_blocks\xbn_doclet contains the 1.4
version of the JavaDoc standard doclet, and that all the code
(1) compiles using the current XBN classes, and that the path to
"doclet_class_map.txt" is correct.
In SOBStringBuffer, ensure that the "1.3.1" section is
uncommented, and the "1.4" section is commented.