Nested RecyclerView需点击Search View才加载的问题求助

核心问题：异步数据加载后未通知Adapter更新 #

Firestore数据查询是异步操作，当数据加载完成并添加到prdModellist后，你没有通知ProductAdapter数据发生变化，导致子RecyclerView无法自动刷新。只有当界面因点击SearchView发生重绘时，才会触发RecyclerView重新绑定，此时数据已加载完成，才会显示出来。

具体修复步骤 #

1. 移除HomeFragment中的冗余代码 #

在onCreateView方法里，创建Adapter后执行的parentModelArrayList = new ArrayList<>();完全多余，还可能引发后续数据混乱，直接删除：

// 删除此行代码
parentModelArrayList = new ArrayList<>();

2. 子Adapter数据更新通知 #

在Firestore查询的onComplete回调中，添加完数据后立即调用productAdapter.notifyDataSetChanged()，通知子RecyclerView刷新数据：

修复「Tasty Snacks」查询回调：

if (task.isSuccessful()) {
    for (QueryDocumentSnapshot queryDocumentSnapshot: task.getResult()) {
        prdModellist.add(new ProductDataModel(
            (String) queryDocumentSnapshot.get("productimage"),
            (String) queryDocumentSnapshot.get("productname"),
            (String) queryDocumentSnapshot.get("description"),
            (Long) queryDocumentSnapshot.get("price"),
            (Long) queryDocumentSnapshot.get("discount")
        ));
    }
    // 通知子Adapter更新数据
    productAdapter.notifyDataSetChanged();
}

修复「Personal Care」查询回调（同时修正拼写错误）：

if (task.isSuccessful()){
    // 修正：将Task.getResult()改为task.getResult()
    for (QueryDocumentSnapshot queryDocumentSnapshot: task.getResult()) {
        prdModellist.add(new ProductDataModel(
            (String) queryDocumentSnapshot.get("productimage"),
            (String) queryDocumentSnapshot.get("productname"),
            (String) queryDocumentSnapshot.get("description"),
            (Long) queryDocumentSnapshot.get("price"),
            (Long) queryDocumentSnapshot.get("discount")
        ));
    }
    // 通知子Adapter更新数据
    productAdapter.notifyDataSetChanged();
}

3. 优化子RecyclerView初始化（可选但推荐） #

每次onBindViewHolder都创建新的LinearLayoutManager和ProductAdapter会浪费性能，建议在ViewHolder初始化时一次性设置：

public class ViewHolder extends RecyclerView.ViewHolder {
    TextView title;
    MaterialButton viewAllBtn;
    RecyclerView prntRView;
    ProductAdapter productAdapter;
    ArrayList<ProductDataModel> prdModellist;

    public ViewHolder(@NonNull View itemView) {
        super(itemView);
        title = itemView.findViewById(R.id.prntTitle);
        viewAllBtn = itemView.findViewById(R.id.viewAllBtn);
        prntRView = itemView.findViewById(R.id.prntRView);
        
        // 仅初始化一次子RecyclerView的布局管理器
        RecyclerView.LayoutManager lm = new LinearLayoutManager(itemView.getContext(), LinearLayoutManager.HORIZONTAL, false);
        prntRView.setLayoutManager(lm);
        
        // 初始化数据列表和Adapter
        prdModellist = new ArrayList<>();
        productAdapter = new ProductAdapter(itemView.getContext(), prdModellist);
        prntRView.setAdapter(productAdapter);
    }
}

@Override
public void onBindViewHolder(@NonNull ViewHolder holder, int position) {
    ParentModel currentItem = parentModelList.get(position);
    holder.title.setText(currentItem.categoryText());
    holder.viewAllBtn.setOnClickListener(v -> showLanding(currentItem.categoryText()));

    // 清空旧数据，避免复用ViewHolder时数据残留
    holder.prdModellist.clear();
    holder.productAdapter.notifyDataSetChanged();

    FirebaseFirestore firebaseFirestore = FirebaseFirestore.getInstance();
    if (currentItem.categoryText().equals("Tasty Snacks")) {
        firebaseFirestore.collection(COLLECTION_NAME).whereEqualTo(CONDITION).get()
                .addOnCompleteListener(task -> {
                    if (task.isSuccessful()) {
                        for (QueryDocumentSnapshot snapshot : task.getResult()) {
                            holder.prdModellist.add(new ProductDataModel(
                                (String) snapshot.get("productimage"),
                                (String) snapshot.get("productname"),
                                (String) snapshot.get("description"),
                                (Long) snapshot.get("price"),
                                (Long) snapshot.get("discount")
                            ));
                        }
                        holder.productAdapter.notifyDataSetChanged();
                    } else {
                        System.out.println(task.getException().getMessage());
                    }
                });
    } else if (currentItem.categoryText().equals("Personal Care")) {
        firebaseFirestore.collection(COLLECTION).whereEqualTo(CONDITION2).get()
                .addOnCompleteListener(task -> {
                    if (task.isSuccessful()) {
                        for (QueryDocumentSnapshot snapshot : task.getResult()) {
                            holder.prdModellist.add(new ProductDataModel(
                                (String) snapshot.get("productimage"),
                                (String) snapshot.get("productname"),
                                (String) snapshot.get("description"),
                                (Long) snapshot.get("price"),
                                (Long) snapshot.get("discount")
                            ));
                        }
                        holder.productAdapter.notifyDataSetChanged();
                    } else {
                        System.out.println(task.getException().getMessage());
                    }
                });
    }
}

额外注意事项 #

• 确保COLLECTION_NAME、CONDITION等常量已正确定义，否则Firestore查询会失败。
• 可添加加载状态提示（如ProgressBar），提升用户体验。
• 建议提前在Fragment/ViewModel中加载所有分类数据，再传递给Adapter，减少重复查询，优化性能。

内容的提问来源于stack exchange，提问作者Vinay N