从Firebase删除在适配器类中

Question

[嗨，我正在尝试从Firebase Realtime数据库中删除一项。我可以将其从Recycler View中删除，但不能从Firebase中删除。

[当前，我试图通过单击recyclerview项中的删除按钮来删除该项，并将此代码放入适配器java类中。

为了将其从Firebase中删除，我缺少什么吗？

我的适配器代码：

public class DailyMealAdapter extends RecyclerView.Adapter<DailyMealAdapter.MyViewHolder> {

    private Context context;
    private List<SelectedMeal> selectedMealList;

    private DatabaseReference ref = FirebaseDatabase.getInstance().getReference("Meals");

    public DailyMealAdapter(Context c, List<SelectedMeal> sm) {
        context = c;
        selectedMealList = sm;
    }

    @NonNull
    @Override
    public MyViewHolder onCreateViewHolder(@NonNull ViewGroup parent, int viewType) {
        View view = LayoutInflater.from(parent.getContext()).inflate(R.layout.dailymeal_item, parent, false);

        DailyMealAdapter.MyViewHolder viewHolder = new DailyMealAdapter.MyViewHolder(view);
        return viewHolder;

    }

    @Override
    public void onBindViewHolder(@NonNull MyViewHolder holder, int position) {
        final int itemPos = position;
        final SelectedMeal selectedMeal = selectedMealList.get(position);
        holder.mealTitle.setText(selectedMeal.getMealName());
        holder.mealCalories.setText(selectedMeal.getCalorieAmount());

        holder.mealDelete.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
          selectedMealList.remove(position);
            notifyItemRemoved(position);
            notifyItemChanged(position, selectedMealList.size());
            final DatabaseReference ref = FirebaseDatabase.getInstance().getReference("Meals");
            final ValueEventListener eventListener = new ValueEventListener() {
                @Override
                public void onDataChange(@NonNull DataSnapshot dataSnapshot) {
                    dataSnapshot.getValue(SelectedMeal.class);
                    ref.child(selectedMealList.get(position).getMealId()).removeValue();
                }

                @Override
                public void onCancelled(@NonNull DatabaseError databaseError) {

                }
            };
            //ref.child(String.valueOf(selectedMealList.get(Integer.parseInt(selectedMeal.getMealId())))).removeValue();
            //deleteMeal(selectedMeal.getMealId(), itemPos);
        }
    });

    }

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

    public class MyViewHolder extends RecyclerView.ViewHolder {
        public TextView mealTitle, mealCalories;
        public Button mealDelete;
        public CardView cardView;

        public MyViewHolder(@NonNull View itemView) {
            super(itemView);
            mealTitle = (TextView) itemView.findViewById(R.id.dailyMealTitle);
            mealCalories = (TextView) itemView.findViewById(R.id.dailyMealCalories);
            cardView = (CardView) itemView.findViewById(R.id.dailyCardView);
            mealDelete = itemView.findViewById(R.id.deleteButton);
        }
    }

Answer 1

您可以试试吗：

class MyViewHolder extends RecyclerView.ViewHolder implements View.OnClickListener {
        public TextView mealTitle, mealCalories;
        public Button mealDelete;
        public CardView cardView;

        public MyViewHolder(@NonNull View itemView) {
            super(itemView);
            mealTitle = (TextView) itemView.findViewById(R.id.dailyMealTitle);
            mealCalories = (TextView) itemView.findViewById(R.id.dailyMealCalories);
            cardView = (CardView) itemView.findViewById(R.id.dailyCardView);
            mealDelete = itemView.findViewById(R.id.deleteButton);
            mealDelete.setOnClickListener(this);

        }

        @Override
        public void onClick(View view) {
            ref.child(selectedMealList.get(getAdapterPosition()).getMealId()).removeValue().addOnSuccessListener(new OnSuccessListener<Void>() {
                @Override
                public void onSuccess(Void aVoid) {
                        selectedMealList.remove(getAdapterPosition());
                        notifyItemRemoved(getAdapterPosition());
                }
            });

        }
    }

onBindViewHolder干净如]

@Override
public void onBindViewHolder(@NonNull MyViewHolder holder, int position) {
    final int itemPos = position;
    final SelectedMeal selectedMeal = selectedMealList.get(position);
    holder.mealTitle.setText(selectedMeal.getMealName());
    holder.mealCalories.setText(selectedMeal.getCalorieAmount());
}