I have two ways of checking if a List is empty or not
if (CollectionUtils.isNotEmpty(listName))
and
if (listName != null
To Check collection is empty, you can use method: .count(). Example:
DBCollection collection = mMongoOperation.getCollection("sequence"); if(collection.count() == 0) { SequenceId sequenceId = new SequenceId("id", 0); mMongoOperation.save(sequenceId); }