如何從Button的onClick偵聽器中刪除Firebase DataBase

Question

我正在使用Recycle Adapter Class在我的應用中顯示Firebase數據，其中包含可供購買的圖書列表。

但是一旦出售一本書，我希望用戶能夠刪除該書，並最終將在onClick of Button上從Firebase數據庫中刪除。 我怎樣才能做到這一點？

這是我的Firebase數據結構：

這是RecycleAdapter類

這是我的適配器數據類：

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();
    }
}

我在上傳課程中使用它來推送Firebase中的數據：

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

Answer 1

如果您知道該書的ID，則應該能夠刪除具有該ID引用的子項。

你必須像之前用holder.bookCall.setOnClickListener（...）那樣實現點擊監聽器;

碼：

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

我希望它對你有所幫助。

Answer 2

您可以對您的bookid放置null以將其從數據庫中刪除。

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

Answer 3

使用此代碼：

        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 4

此代碼將刪除您想要的書，只需獲取該書的ID並放在onClickListener中：

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

Answer 5

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