What are the conditions when QuerySnapshot will give size zero even though there is document in Collection? [duplicate] I am trying to traverse through every documents in my newsfeeds Collection for getting data and add the data to a ArrayList. My each document in newsfeed contains two collections FeedNewsFeeds and FeedUserName ,which in their own contains documents. when I tried to get QuerySnapshot of newsfeeds collection ,i was unable, querySnapshot.size() always shows 0 . I have no idea how to handel this. <a...