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Re: J/Link

• To: mathgroup at smc.vnet.net
• Subject: [mg27381] Re: J/Link
• From: tgayley at wolfram.com (Todd Gayley)
• Date: Thu, 22 Feb 2001 02:25:28 -0500 (EST)
• Organization: Wolfram Research, Inc.
• References: <96vthm$9i@smc.vnet.net>
• Sender: owner-wri-mathgroup at wolfram.com

On 21 Feb 2001 03:16:54 -0500, Rainer Gruber <rainer.gruber at students.uni-linz.ac.at>
wrote:

>Hi there,
>
>I have a little problem using J/Link.
>I have two computers with Mathematica 4.0.1.0 running under Windows 98. On both devices there is the same Java version installed. On one computer J/Link works fine, on the the other one it does not run at all!
>
>Though its possible to start Java with InstallJava[] I can't create a Java object with JavaNew[] or LoadClass[] but I always get an error message like
>LoadClass::"fail" :  Java failed to load class ...
>
>I have tried all possibilities for PATH and CLASSPATH but I had no success!
>
>The only idea I have: On the computer where J/Link doesn't work I've another directory structure than the usual one (C:\Mathematica4\... instead of C:\Programme\Wolfram Research\Mathematica\4.0\... or so).
>
>Is this an obstacle problem for J/Link?

Rainer,

Having a non-standard directory structure is not a problem. What happens if you do this:

LoadClass["java.lang.Object"]

If it fails, do you get error messages other than LoadClass::fail? Do you see any output
in the Java stdout window? If you do, then that will be the crucial piece of evidence to
determine the problem.

If this succeeds, then J/Link is working. If you cannot load some specific classes on one
machine, it is most likely a CLASSPATH problem.

You might want to reinstall J/Link. You will have problems if you have components from
different versions of J/Link mixed together. Sometimes people don't realize that they
still have an old copy of JLinkNativeLibrary.dll or JLink.jar kicking around.


Todd Gayley
Wolfram Research