我試圖從我使用FirebaseRecylerAdapter的方法中檢索數據database，如下所示fragment onViewCreated@Override    public void onViewCreated(View view, @Nullable Bundle savedInstanceState) {        super.onViewCreated(view, savedInstanceState);        FirebaseRecyclerAdapter<AllUsers, AllUsersViewHolder> firebaseRecyclerAdapter;    }    public static class AllUsersViewHolder extends RecyclerView.ViewHolder {        View view;        public AllUsersViewHolder(View itemView) {            super(itemView);            view = itemView;        }    }當我使用firebaseRecyclerAdapter = new FirebaseRecyclerAdapter它不會給我populateViewHolder方法只是給下面的方法FirebaseRecyclerAdapter<AllUsers, AllUsersViewHolder> firebaseRecyclerAdapter = new FirebaseRecyclerAdapter<AllUsers, AllUsersViewHolder>() {            @Override            protected void onBindViewHolder(AllUsersViewHolder holder, int position, AllUsers model) {            }            @Override            public AllUsersViewHolder onCreateViewHolder(ViewGroup parent, int viewType) {                return null;            }        };有人可以告訴我為什么會這樣嗎