如何更改集合下文档中特定字段的值？

Question

待处理集合下的所有文档都在RecyclerView中列出，如屏幕截图所示。单击特定项目时，将显示带有3个选项的“警报”对话框。单击“ 已发货”选项后，我要将状态字段的值从该特定项目的“ 已订购”更改为“ 已发货” 。该怎么做？请帮忙。

holder.cl.setOnClickListener(new View.OnClickListener() {
                @Override
                public void onClick(View view) {
                    CharSequence options[]  = new CharSequence[]{
                            "Shipped", "Out for Delivery", "Delivered"
                    };

                    AlertDialog.Builder builder = new AlertDialog.Builder(CheckOrders.this);
                    builder.setTitle("What's the order status?");
                    builder.setItems(options, new DialogInterface.OnClickListener() {
                        @Override
                        public void onClick(DialogInterface dialog, int i) {
                            if (i == 0){

                                db.collection("Pending").get()
                                        .addOnCompleteListener(new OnCompleteListener<QuerySnapshot>() {
                                            @RequiresApi(api = Build.VERSION_CODES.N)
                                            @Override
                                            public void onComplete(@NonNull Task<QuerySnapshot> task) {
                                                if (task.isSuccessful()){
                                                    for (QueryDocumentSnapshot document : task.getResult()){
                                                        db.collection("Pending").document(String.valueOf(documentSnapshots.get(position).getData().replace("status", "shipped")));
                                                    }
                                                }
                                            }
                                        });
                            }else if (i==1){
                                OutforDelivery();
                            }
                            else if (i==2){
                                Delivered();
                            }else {}
                        }
                    });
                    builder.show();
                }
            });