如何从Button的onClick侦听器中删除Firebase DataBase

Question

我正在使用Recycle Adapter Class在我的应用中显示Firebase数据，其中包含可供购买的图书列表。

但是一旦出售一本书，我希望用户能够删除该书，并最终将在onClick of Button上从Firebase数据库中删除。我怎样才能做到这一点？

这是我的Firebase数据结构：

这是RecycleAdapter类

这是我的适配器数据类：

public class SubjectBooksAdapter extends RecyclerView.Adapter<SubjectBooksAdapter.MyViewHolder> {
    ArrayList<Books> bookslist;
    CardView cv;
    FirebaseAuth fauth;
    FirebaseDatabase database;
    DatabaseReference dbreference;
    Books b;

    public SubjectBooksAdapter(ArrayList<Books> bookslist){
        this.bookslist = bookslist;
    }

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

    public class MyViewHolder extends RecyclerView.ViewHolder {
        TextView bookName,bookAuthor,bookDesc,bookPrice,bookCall;
        ImageView iv;
        Button delete;

        MyViewHolder(final View itemView) {
            super(itemView);
            cv = (CardView) itemView.findViewById(R.id.my_card_view);

            iv = (ImageView) itemView.findViewById(R.id.imageView);

            database = FirebaseDatabase.getInstance();
            dbreference = database.getReference("books");
            bookName = (TextView) itemView.findViewById(R.id.bookName);
            bookAuthor = (TextView) itemView.findViewById(R.id.bookAuthor);
            bookDesc = (TextView) itemView.findViewById(R.id.bookDesc);
            bookPrice = (TextView) itemView.findViewById(R.id.bookPrice);
            bookCall = (TextView) itemView.findViewById(R.id.bookCall);
            fauth = FirebaseAuth.getInstance();

            delete = (Button) itemView.findViewById(R.id.delete);
        }
    }

    @Override
    public void onBindViewHolder(final MyViewHolder holder, final int position) {
        database = FirebaseDatabase.getInstance();
        dbreference = database.getReference("books");

        b = bookslist.get(position);
        holder.bookName.setText(b.getBname());
        holder.bookAuthor.setText(b.getBauthor());
        holder.bookDesc.setText(b.getBdesc());
        holder.bookPrice.setText("Rs. "+b.getPrice());
        holder.bookCall.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                //Log.e("Current user is ", fauth.getCurrentUser().getEmail());
                b = bookslist.get(position);
                String[] arr = {b.getSelleremail(),b.getSellername(),b.getBname(),b.getBauthor()};
                //Log.e("Seller is ",b.getSellername());
                Intent in = new Intent(v.getContext(),Chat.class);
                in.putExtra("seller",arr);
                v.getContext().startActivity(in);
            }
        });
        Glide.with(cv.getContext()).load(Uri.parse(b.getPics())).placeholder(R.drawable.bshelf).error(R.drawable.bshelf).into(holder.iv);
    }

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

我在上传课程中使用它来推送Firebase中的数据：

 String bookid = dbreference.child("books").child(item).push().getKey();
                dbreference.child("books").child(item).child(bookid).setValue(b);

Answer 1

使用此代码：

        DatabaseReference driverRef = FirebaseDatabase.getInstance().getReference().child("bname");

                                    driverRef.removeValue();

    if you delete whole database
    use this

      DatabaseReference driverRef = FirebaseDatabase.getInstance().getReference();
    driverRef.removeValue();

//---------------------Use on Button click Listener--------

        setContentView(R.layout.activity_main);
Button button=findViewById(R.id.btn);
button.setOnClickListener(new View.OnClickListener() {
    @Override
    public void onClick(View view) {
        DatabaseReference driverRef = FirebaseDatabase.getInstance().getReference().child("bname");

        driverRef.removeValue();
    }
});

Answer 2

您可以将null放在bookid上，以便从数据库中删除它。

dbreference.child("books").child(bookId).setValue(null);

Answer 3

如果您知道该书的ID，则应该能够删除具有该ID引用的子项。

你必须像之前用holder.bookCall.setOnClickListener（...）那样实现点击监听器;

码：

holder.delete.setOnClickListener(new View.OnClickListener() {
        @Override
        public void onClick(View view) {
            dbreference.child("books").child(bookId).remove();
        }
    });

我希望它对你有所帮助。

Answer 4

此代码将删除您想要的书，只需获取该书的ID并放在onClickListener中：

dbreference.child("books").child(item).child(bookid).removeValue();

Answer 5

dbref.child("books").child("Computer Science").child(key).removeValue();