Invoking Java from C and capturing System.out

Hi,
I know very little about C but have a question related to invoking a Java process from C. Perhaps someone can help me.
I've been looking at the example at http://java.sun.com/docs/books/jni/html/invoke.html and seen how to invoke my Java program with:
(*env)->CallStaticVoidMethod(env, cls, mid, args);
in their example the Java program prints one line to System out with:
System.out.println("Hello World " + args[0]);
and says running the program produces:
Hello World from C!
What I want to know is, how in the C program can I capture the output the Java program sends to System.out, as I want to do something with the output other than have it print into the console.
Hope that makes sense.

I'm not totally clear on your question but I'll take a stab.
It seems to me like you are trying to get the output from a java program into a C program. If this is the case then there are many ways to do this - many of which are more simple that using JNI. However, if you absolutely must use JNI for this application then I suggest you take some more time to learn about C and JNI as I imagine this sort of thing is non-trivial and will required a level of understanding of C that you currently don't have. You may also want to cross-post onto the JNI forum.
If you can do this without using JNI then I'd suggest doing the standard fork/exec/pipe routine. This means, that in your C program you will call the functions fork (to create a new process that is subordinate to the currently running one), exec (in the subprocess which will replace the current program image in memory with that of another program you wish to execute, in this case, a JVM with a running application), and popen (which creates a "pipe" between the standard output of the Java program [System.out] and some input stream in the C program).
Finding an example of a program that does this fork/exec/pipe pattern on the web shouldn't be too hard. Hope this helps.
-mike

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Edited by: Christian Sy on Mar 9, 2010 10:17 AM

Invoking Java from C and capturing System.out

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