RecyclerView未显示来自Firestore的数据

// 初始化Firestore
FirebaseFirestore db = FirebaseFirestore.getInstance();

// 查询数据
db.collection("items")
    .get()
    .addOnCompleteListener(new OnCompleteListener<QuerySnapshot>() {
        @Override
        public void onComplete(@NonNull Task<QuerySnapshot> task) {
            if (task.isSuccessful()) {
                List<Item> items = new ArrayList<>();
                for (QueryDocumentSnapshot document : task.getResult()) {
                    Item item = document.toObject(Item.class);
                    items.add(item);
                }
                // 设置适配器
                ItemAdapter adapter = new ItemAdapter(items);
                recyclerView.setAdapter(adapter);
            } else {
                Log.d(TAG, "Error getting documents: ", task.getException());
            }
        }
    });