这是什么“RecyclerView 没有 LayoutManager androidx.recyclerview.widget.RecyclerView”错误？

Question

I'm trying to retrieve data from firebase. But it shows "RecyclerView has no LayoutManager androidx.recyclerview.widget.RecyclerView" error? Can somebody help me to fix this error please? Error Image

NewsAdapter.java

private List<NewsModel> newsModels;

    public NewsAdapter( List<NewsModel> newsModels) {
        this.newsModels = newsModels;
    }

    @NonNull
    @Override
    public NewsViewHolder onCreateViewHolder(@NonNull ViewGroup parent, int viewType) {
        View view = LayoutInflater.from(parent.getContext()).inflate(R.layout.news,parent,false);
        return new NewsViewHolder (view);
    }

    @Override
    public void onBindViewHolder(@NonNull NewsViewHolder holder, int position) {
        NewsModel news = newsModels.get(position);

        holder.textViewName.setText(news.getName());
        holder.textViewBrand.setText(news.getBrand());
        holder.textViewDesc.setText(news.getDescription());
        holder.textViewPrice.setText("INR " + news.getPrice());
        holder.textViewQty.setText("Available Units: " + news.getQty());
    }

    @Override
    public int getItemCount() {
        return newsModels.size();
    }

    class NewsViewHolder extends RecyclerView.ViewHolder {

        TextView textViewName, textViewBrand, textViewDesc, textViewPrice, textViewQty;

        public NewsViewHolder(View itemView) {
            super(itemView);

            textViewName = itemView.findViewById(R.id.textview_name);
            textViewBrand = itemView.findViewById(R.id.textview_brand);
            textViewDesc = itemView.findViewById(R.id.textview_desc);
            textViewPrice = itemView.findViewById(R.id.textview_price);
            textViewQty = itemView.findViewById(R.id.textview_quantity);

        }


    }
}

Answer 1

if you haven't added a recycler view then you could just add it through xml code like this

<androidx.recyclerview.widget.RecyclerView
 android:id="@+id/contentContainer"
 android:orientation="vertical"
 app:layoutManager="androidx.recyclerview.widget.LinearLayoutManager"
 android:layout_width="match_parent"
 android:layout_height="match_parent" />

Answer 2

in your activity that you want use recyclerView:

RecyclerView recyclerView  =   findViewById(R.id.recyclerVeiw);
recyclerView.setLayoutManager(new LinearLayoutManager(this));
recyclerView.setAdapter(new YourAdapeter());