JNI: Getting String | StringBuffer to Java from C using input argument

Question

I've written a native method in C which takes command String from Java, executes the command, and obtains both an integer return_code and a C-string result_string as an output. The return_code goes back to Java from the return statement at the end of the native method...my problem is, that I would like to pass into the native method either a String or StringBuffer, and use that to relay the result_string back to the Java code, as well. Eg., loosely, if I have a
JNIEXPORT jint JNICALL ExecuteCmd
(JNIEnv *env, jclass jcls, jstring cmdString, jobject returnBuffer)
where jobject returnBuffer is a StringBuffer created as StringBuffer(2048), I'd like to take return_string once I have it and do something like
returnBuffer = env->NewStringUTF(result_string);
(I know the syntax env->NewStringUTF is a bit different to what's in the JNI book, but it's what works on the HP-UX system I'm using.)
I know already that this particular bit of code doesn't work. My question is, does the general idea have any potential to work, or am I trying to do something that's impossible?

Answer 1

Your general approach works just fine. What you have to do is use JNI to find the appropriate method for the StringBuffer class, and invoke it.