Simple JNI string passing test from example crashes

Question

Greetings
I am trying to get the following to work:
JNIEXPORT void JNICALL
Java_src_torchtechnologies_excubitore_ExcubitoreController_initialize (JNIEnv *jenv, jobject job, jstring dialog_name)
const char str = (jenv)->GetStringUTFChars(jenv, dialog_name, 0);
(*jenv)->ReleaseStringUTFChars(env, dialog_name, str);
The class is:
public class ExcubitoreController {
public native void initialize(String dialog_file_name);
static {
System.loadLibrary("excubitore");
public static void main(String[] args) {
ExcubitoreController a = new ExcubitoreController();
     String dialog_file_name = "test.dlg";
a.initialize(dialog_file_name);
This is all very simple and right out of the examples. It compiles OK, it loads OK, but it throws signal 11 (segmentation fault) and dumps. I've been beating on it for hours and can't make any progress. Can anybody offer a suggestion?
Thanks
Mike

Answer 1

Which JNI call crashes -- GetStringUTFChars or ReleaseStringUTFChars? Or does it work if you comment out both to make the native method a no-op?