Implementing a Two-Level Comment Feature in Android Using Nested RecyclerViews

During Android app development, a comment section with both primary comments and replies is essential; this article describes the author's approach to implementing such a feature using a nested RecyclerView structure.

Database design includes a Comment entity with fields such as id (primary key), newsId , number (user ID), content , time , level (1 for top‑level, 2 for replies), replyNumber , and replyId (used only for level‑2 comments).

The Data Access Object (DAO) encapsulates typical SQL operations: inserting a comment, deleting by ID, retrieving all comments for an article, retrieving a user's comments, and fetching a comment by its ID.

Layout consists of three main parts: the article detail page showing a RecyclerView for top‑level comments, an adapter layout that itself contains another RecyclerView for replies, and a simple second‑level adapter layout built from a few TextView components.

Code logic is handled in the ViewModel, where all comments for a given article are loaded into a MutableLiveData<List<CommentInfo>> . The primary adapter receives only comments with level == 1 , while a filtered list of level == 2 comments is passed to the reply adapter. Binding the ViewHolder involves counting top‑level items, filtering related replies, and invoking callbacks for actions such as replying.

var comments = MutableLiveData<List<CommentInfo>>()
comments.value = commentStoreRepository.getCommentsByNewId(newsId)

The article also shows screenshots of the final UI, demonstrating both the overall comment list and the “My Comments” view, and notes a minor issue where an empty replyNumber prevented the article author’s details from displaying.

In conclusion, the author successfully created a functional two‑level comment system, inviting feedback and reminding readers to credit the source when reposting.