为什么我不能使用populateViewHolder覆盖方法？

Question

我试图从我使用FirebaseRecylerAdapter的方法中检索数据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;        }    }当我使用firebaseRecyclerAdapter = new FirebaseRecyclerAdapter它不会给我populateViewHolder方法只是给下面的方法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;            }        };有人可以告诉我为什么会这样吗