我如何将Recyclerview连接到Firebase数据库插入，更新和删除数据

Question

我创建了一个包含recyclerview的应用程序，并根据用户的点击从recyclerview arrayList的{​​{1}}中添加了数据，然后根据用户的点击编辑，删除了alertDilog中的数据。但是当我将我的应用程序连接到AlertDilog时，我的应用程序无法正常工作。

Recyclerview适配器：

firebase Database

和物品类别：

public class recyclerviewadapter extends RecyclerView.Adapter<recyclerviewadapter.Viewholder> {
        ArrayList<customitem> datalist;
        vonclick mclick;

        @NonNull
        @Override
        public Viewholder onCreateViewHolder(@NonNull ViewGroup parent, int viewType) {
            View v = LayoutInflater.from(parent.getContext()).inflate(R.layout.recyclerviewexdesign,parent,false);
            return new Viewholder(v,mclick);
        }

        public recyclerviewadapter(ArrayList<customitem> datalist) {
            this.datalist = datalist;
        }

        @Override
        public void onBindViewHolder(@NonNull Viewholder holder, int position) {
            customitem n = datalist.get(position);
            holder.productname.setText(n.getproductname());


        }

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

        public class Viewholder extends RecyclerView.ViewHolder {
            TextView productname;
            public Viewholder(@NonNull View itemView, final vonclick listener) {
                super(itemView);
                productname = itemView.findViewById(R.id.titleid);

                itemView.setOnClickListener(new View.OnClickListener() {
                    @Override
                    public void onClick(View v) {
                        if (listener!=null){
                            int possition =getAdapterPosition();
                            if (possition !=RecyclerView.NO_POSITION){
                                listener.cclick(possition);

                            }

                        }


                    }
                });
            }
        }
        public interface vonclick{
            void cclick(int possition);

        }
        public void recyclerviewonclicl(vonclick possition){
            mclick=possition;
        }
    }

最后一个主班：

public class customitem {
    String productname,size,price,box;
    int kg;
    public customitem(){

    }

    public customitem(String productname, String size,String price,String box,int kg) {
        this.productname = productname;
        this.size = size;
        this.price = price;
        this.box = box;
        this.kg = kg;
    }

    public String getproductname() {
        return productname;
    }

    public void setproductname(String productname) {
        this.productname = productname;
    }

    public String getsize() {
        return size;
    }

    public void setsize(String size) {
        this.size = size;
    }

    public String getPrice() {
        return price;
    }

    public void setPrice(String price) {
        this.price = price;
    }

    public String getBox() {
        return box;
    }

    public void setBox(String box) {
        this.box = box;
    }

    public int getKg() {
        return kg;
    }

    public void setKg(int kg) {
        this.kg = kg;
    }
}