我正在嘗試將學生從用戶集合中提取到回收站視圖中，但它說沒有附加的adpater.提取兩件事（1）學生姓名（2）列表視圖上的卷號    public class availablestudent_fragment extends Fragment {    private static final String TAG ="FireLog" ;    private RecyclerView nmainlist;    private FirebaseFirestore mfirestore;    private List<Users> usersList;    private UserListAdapter userListAdapter;    @Nullable    @Override    public View onCreateView(@NonNull LayoutInflater inflater, @Nullable ViewGroup container, @Nullable Bundle savedInstanceState) {        View v=inflater.inflate(R.layout.fragment_availablestudents,null);        nmainlist=(RecyclerView)v.findViewById(R.id.main_list);        nmainlist.setHasFixedSize(true);        nmainlist.setLayoutManager(new LinearLayoutManager(getContext()));        nmainlist.setAdapter(userListAdapter);        mfirestore=FirebaseFirestore.getInstance();      usersList=new ArrayList<>();      userListAdapter=new UserListAdapter(usersList);        mfirestore.collection("users").addSnapshotListener(new EventListener<QuerySnapshot>() {            @Override            public void onEvent(@javax.annotation.Nullable QuerySnapshot queryDocumentSnapshots, @javax.annotation.Nullable FirebaseFirestoreException e) {                if (e != null) {                    Log.d(TAG, "Error" + e.getMessage());                }                for (DocumentChange doc : queryDocumentSnapshots.getDocumentChanges()) {                    if (doc.getType() == DocumentChange.Type.ADDED) {                        Users users = doc.getDocument().toObject(Users.class);                        usersList.add(users);                        userListAdapter.notifyDataSetChanged();                    }                }            }        });        return v;    }}現在這里的問題是，卷號的提取方式與提取學生姓名的方式相同，這是否給我帶來了問題？