Returning new objects on uninitialized native code arguments

Question

I have a C library I am trying to interface to that returns arrays whose size
I do not know in advance. I would like to be able to write a java wrapper
library that accepts uninitialized java arrays as arguments, and creates
arrays of the appropriate size, and gives them back to the Java code.
In the code below, I try to pass an uninitialized String array to native
function, and create the String array in the native function. The String
array "str" is still null after the native function returns. I can make it
work by creating the String array in the java code, or making the return value
a String array created in the native code. Why doesn't it work when I pass an
uninitialized array as a parameter?
Java:
public native int getStrings(int length, String [] strings);...
String [] str= null;
int result = test.getStrings(10,str);C:
JNIEXPORT jint JNICALL Java_StringArrayTest_getStrings
(JNIEnv *env, jobject obj, jint length, jobjectArray strings)
    //create the java string array
   jclass elementType = (*env)->FindClass(env,"java/lang/String");
    if(NULL==elementType) return -1;
    strings=(*env)->NewObjectArray(env,length,elementType,NULL);
    if(NULL==strings)      return -1;
   jsize i;
    for(i=0; i<length; i++)
     char buf[100];
     snprintf(buf,99,"String %i",(int) i);
     jstring tempString=NULL;
     tempString=(*env)->NewStringUTF(env,buf);
     if(NULL==tempString) return -1;
     (*env)->SetObjectArrayElement(env, strings, i, tempString);
    return 0;
}

Answer 1

That kind of return-by-reference is not supported in Java. Consider: could it work if getStrings were written in Java language instead of native code? The answer is no.
-slj-