JNI and jar files

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Steve Sobol - 19 Aug 2007 20:41 GMT

I have a C++ program that loads and executes a method in a Java class using
the Invocation API. Easy enough to do, but I was wondering if I could do
something like

java -jar myApp.jar

from the C++ program? At the very least, I know what class and method
I'm going to call, so couldn't I just include myApp.jar in the class
path (via "-Djava.class.path=myApp.jar"), load the class and call the
proper method?

Thanks

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Steve Sobol, Victorville, California PGP:0xE3AE35ED
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Gordon Beaton - 20 Aug 2007 08:16 GMT

> I was wondering if I could do something like
>
[quoted text clipped - 4 lines]
> path (via "-Djava.class.path=myApp.jar"), load the class and call the
> proper method?

Do you mean including that in the options field of the vm_args
structure passed to JNI_CreateJavaVM?

I would expect it to work, but have never tried. You should be able to
invoke the appropriate main method from the jarfile in the "normal"
way for invocation.

What happened when *you* tried?

/gordon

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Steve Sobol - 20 Aug 2007 15:17 GMT

> I would expect it to work, but have never tried. You should be able to
> invoke the appropriate main method from the jarfile in the "normal"
> way for invocation.
>
> What happened when *you* tried?

I subsequently tried it, including the jar file in the classpath, and it
seems to work. There are some issues - but I don't believe they're directly
related to JNI.

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Roedy Green - 20 Aug 2007 11:52 GMT

>java -jar myApp.jar
>from the C++ program?

JNI lets C++ call Java or the reverse. C++ also has an exec so it
can spawn an entire new JVM too.

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JNI and jar files

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