java - 调用 Firebase recyclerview 查询的语法

Question

我正在创建一个查询，以按 fragment 中的时间戳对我的 firebase recyclerview 进行排序。我有一个关于如何调用查询的语法问题。

这是我的代码 fragment 。我不确定如何编写“query.addListenerForSingleValueEvent(?????)”这一行

public void onStart(){
    super.onStart();

    FirebaseRecyclerOptions<Posts> options =
            new FirebaseRecyclerOptions.Builder<Posts>()
            .setQuery(usersRef, Posts.class)

            .build();

    Query query = FirebaseDatabase.getInstance().getReference("postId").orderByChild("timestamp").limitToFirst(100);

    query.addListenerForSingleValueEvent(????)

    FirebaseRecyclerAdapter<Posts, viewPostsViewHolder> adapter =
            new FirebaseRecyclerAdapter<Posts, viewPostsViewHolder>(options) {
                @Override
                protected void onBindViewHolder(@NonNull final viewPostsViewHolder holder, final int position, @NonNull Posts model) {

                    final String postId = getRef(position).getKey();

                    usersRef.child(postId).addValueEventListener(new ValueEventListener() {
                        @Override
                        public void onDataChange(@NonNull final DataSnapshot dataSnapshot) {

                            Log.e("heredata","heredata"+dataSnapshot);

                            if (dataSnapshot.exists()) {

提前感谢任何帮助

Answer 1

如果您尝试在回收器 View 中显示查询结果，您应该将该查询传递到构建器的 setQuery(...) 调用中:

Query query = FirebaseDatabase.getInstance().getReference("postId").orderByChild("timestamp").limitToFirst(100);

FirebaseRecyclerOptions<Posts> options =
        new FirebaseRecyclerOptions.Builder<Posts>()
                                   .setQuery(query, Posts.class)
                                   .build();