Re: Calling Java from RPG

hi Nick,

Nick Arndt wrote:

I now can find my class, but it gives me a
java.lang.UnsupportedClassVersionError

This means that the version of Java the class was compiled for isn't compatible with the version of the JVM you're trying to run it on. For example, if you compiled it for version 1.4, it may not run on a 1.1.8 JVM since the 1.4 version might be using functionality that was not available in 1.1.8.

I'd start by determining which versions of Java are installed on your machine. GO LICPGM option 10 should tell you that (you may have to scroll down... look for the 57xxJV1 entries)

If you have more than one installed, you may need to control which one gets started. Please be aware that the version reported in QShell when running "java -version" is not necessarily the same one that RPG decides to use. I'm not sure why that's the case, but they're not always the same.

You can control which version of the JVM gets run using the QIBM_RPG_JAVA_PROPERTIES environment variable. Something like this might work:

ADDENVVAR ENVVAR(QIBM_RPG_JAVA_PROPERTIES) VALUE('-Djava.version=1.4;')

In this case, I'm instructing RPG to load version 1.4 of the JVM. Note that you have to specify -Djava.version=1.5 (not 5.0) in order to get Java 5.0 to load. Sun used the number 1.5 internally, but marketed the product under the moniker "5.0"... which is a little confusing... but, rest assured that -Djava.version=1.5 will give you version 5.0. (I haven't tried it, but I believe the same is true for 6.0, you have to specify version=1.6)