我试图在jni中创建一个长数组，基本上是一些矩形坐标。我试图将其存储在一个已经在java类中创建的长数组中。下面是创建该数组的java代码：

private long[] faceArray = new long[10];

下面是我的jni代码，用于创建和替换 faceArray :

void CreateJavaLongArray(JNIEnv *env, jlongArray& jLongArray, jobject thiz,
                         std::multiset<dlib::rectangle> mset) {
    jclass cls = env->GetObjectClass(thiz);
    jfieldID jLongArrayId = env->GetFieldID(cls, "faceArray", "[J");
    jLongArray = (jlongArray) env->GetObjectField(thiz, jLongArrayId);
    jlong* body = env->GetLongArrayElements(jLongArray, 0);
    env->ReleaseLongArrayElements(jLongArray, body, JNI_ABORT);
    jLongArray = env->NewLongArray(mset.size() * 4);
    if (mset.empty()) {
        ALOGE("No unknown face found...");
        return;
    }
    int i = 0;
    ALOGI("Size of the rect set is: %d", mset.size());
    const int size = mset.size() * 4;
    long long arr[size];
    for (auto rect : mset) {
        arr[i++] = (long long)rect.left();
        arr[i++] = (long long)rect.top();
        arr[i++] = (long long)rect.right();
        arr[i++] = (long long)rect.bottom();
    }
    env->SetLongArrayRegion(jLongArray, 0, mset.size() * 4, arr);
}

但是当我运行代码时，我发现java端的数组没有改变。尺寸还是10码。我做错什么了？