// Calling method. Return String to android.
jstring
getKeyFromC(JNIEnv *env, jobject thiz) {
    char *key = getKey();
    jstring str = (*env)->NewStringUTF(env, key);
    return str;
}

// Called method.
getKey(){
    char key[1555] = "....";
    return &keys[0];
}

JNI DETECTED ERROR IN APPLICATION: input is not valid Modified UTF-8: illegal
start byte 0xb6