I have a object store in Java. My C program stores data (in form of char array) in java. Now I wish to retrieve data from my store. I cannot find any function call that returns me an char array. How can I do this?
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Your question still needs to be cleaned up a little. How does your C program store something in Java? Have you worked out all of the character encoding issues?user124493– user1244932009-08-04 13:46:06 +00:00Commented Aug 4, 2009 at 13:46
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1 Answer
You need to use one of the various API's provided by JNI, probably GetCharArrayElements().
Following is an example, taken from working code which retrieves a byte array from Java into C (the code is a function which is invoked by Java, but the mechanics are identical).
JNIEXPORT void JNICALL Java_xxx_jniEnqueue(JNIEnv *jep,jobject thsObj,
jlong handle, jbyteArray jvaKey, jint jvaKeyOfs, jint jvaKeyLen, jbyteArray jvaData, jint jvaDtaOfs, jint jvaDtaLen) {
jbyte *jniKey,*jniData;
jthrowable escObj;
jniKey=(*jep)->GetByteArrayElements(jep,jvaKey,0);
jniData=(*jep)->GetByteArrayElements(jep,jvaData,0);
...
memcpy(odp->enqpfx->Msg,jniKey+jvaKeyOfs,(vuns)jvaKeyLen); /* key badly named Msg */
...
// enqueue data using key
if(/* enqueue failed */) {
(*jep)->ReleaseByteArrayElements(jep,jvaKey ,jniKey ,JNI_ABORT); /* abort to not copy back */
(*jep)->ReleaseByteArrayElements(jep,jvaData,jniData,JNI_ABORT); /* abort to not copy back */
throwEscapeObject(jep,escObj);
return;
}
(*jep)->ReleaseByteArrayElements(jep,jvaKey ,jniKey ,JNI_ABORT); /* abort to not copy back */
(*jep)->ReleaseByteArrayElements(jep,jvaData,jniData,JNI_ABORT); /* abort to not copy back */
}
