JNI : create an jobjectArray without knowing the size in advance

Question

I would like to return an array of strings from C to Java using JNI. I saw that I could use NewObjectArray() this way:

JNIEXPORT jobjectArray JNICALL Java_Array_initStringArray(JNIEnv *env, jclass cls, jint size)
{
 jclass stringCls = (*env)->FindClass(env, "Ljava/lang/String;");
 if (stringCls == NULL) return NULL;

 jstringArray result = (*env)->NewObjectArray(env, size, StringCls, NULL);
 if (result == NULL) return NULL; 
 ...
}

But here, I don't know the int size parameter: I don't know the number of strings I'll use to populate my array. So is there a way to create an jobjectArray without knowing in advance the size of the array?

Something like creating an empty array and then adding jobject one by one to that array?

---

EDIT : solution using an ArrayList as Edwin suggested

jclass arrayClass = (*jenv)->FindClass(jenv, "java/util/ArrayList");
  if (arrayClass == NULL)   return NULL;

jmethodID mid_init =  (*jenv)->GetMethodID(jenv, arrayClass, "<init>", "()V");
  if (mid_init == NULL) return NULL;

jobject objArr = (*jenv)->NewObject(jenv, arrayClass, mid_init));
  if (objArr == NULL) return NULL;

mid_add = (*jenv)->GetMethodID(jenv, arrayClass, "add", "(Ljava/lang/Object;)Z");
  if (mid_add == NULL) return NULL;

Then in a loop I create an jobject obj for each new object I need to add to the arrayList:

jboolean jbool = (*jenv)->CallBooleanMethod(jenv, objArr, mid_add, obj);
  if (jbool == NULL) return NULL;

Answer 1

If you want to have the backing store (the array) grow as you add to it, use a java.util.ArrayList. It might mean a few more JNI calls (to set up the object), but in your case it sounds like it's worth the effort.