RE: Can I detect Java version before my java program starts?

I posted your question to the JT400 Support Forums and Jeff Lee there
posted this link:

http://publib.boulder.ibm.com/infocenter/iseries/v5r3/ic2924/index.htm?i
nfo/rzaha/sysprop.htm

And then check out the link near the top of that page for the "List of
Java system properties"

I think you can use the information found there to figure out what you
need to look at to determine what JVM is going to get used... since that
is how OS/400 will do it.

I am curious though why you need to add the tools.jar to the classpath?
That just seems odd to me.

Dan Feather

-----Original Message-----
From: java400-l-bounces@xxxxxxxxxxxx
[mailto:java400-l-bounces@xxxxxxxxxxxx] On Behalf Of TitanRebel
Sent: Thursday, August 04, 2005 12:44 PM
To: Java Programming on and around the iSeries / AS400
Subject: Re: Can I detect Java version before my java program starts?

Thanks for the suggestions and the logic!

Now, does anyone know of a way to determine which version is going to be

used?  I don't think it automatically uses the highest version (am I 
wrong?)  It seems to be different based on version, release, and 
modification of OS400.

I guess I could find out what the default is for each VRM of OS400 and 
add logic to the script to take this into account.  Then I would also 
have to look for the existance of .props files (I forget the location 
and names right now) that could also determine which version is going to

be used.  I was just hoping there was an "easier" way to tell.

Thanks,

Ken


Bruce Jin wrote:
> You can try these two methods:
> 
> 1. In CL check the folder existence to decide if a particular JDK 
> version is installed. E.g. /QIBM/ProdData/Java400/jdk14 is the
location 
> of JDK 1.4.
> 2. If you call qshell scripts in CL you can check installed JDK using 
> something like this:
> jdk14=/QIBM/ProdData/Java400/jdk14
> jdk13=/QIBM/ProdData/Java400/jdk13
> jdk12=/QIBM/ProdData/Java400/jdk12
> if cd $jdk14
>   then jv=4
> elif cd $jdk13
>   then jv=3
> elif cd $jdk12
>   then jv=2
> else
>   echo Connot find $jdk12 or $jdk13 or $jdk14!
> fi
> jdk=/QIBM/ProdData/Java400/jdk1$jv
> echo Found JDK 1.$jv, use $jdk.
> export -s JAVA_HOME=$jdk
> 
> I hope someone has better ways to do this.
> 
> Bruce
>