我正在尝试构建一个android应用程序，在其中导入手机中的所有联系人，然后检查手机号码是否存在于用户节点中。如果否，则itemview的可见性将消失，如果是，则可见性将可见。但是，一旦它是可见的，我想获得该特定用户的id，以便我可以执行一些特定的任务。

contactsadapter.java

public class ContactsAdapter extends RecyclerView.Adapter<ContactsAdapter.ViewHolder> {

    Activity activity;
    ArrayList<Contacts> arrayList;
    DatabaseReference userRef = FirebaseDatabase.getInstance().getReference("Users");

    public ContactsAdapter(Activity activity, ArrayList<Contacts> arrayList){
        this.activity = activity;
        this.arrayList = arrayList;
        notifyDataSetChanged();
    }

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

    @Override
    public void onBindViewHolder(@NonNull ContactsAdapter.ViewHolder holder, int position) {

        Contacts model = arrayList.get(position);

        String phoneNo = model.getNumber();
        phoneNo = phoneNo.replaceAll("\\s", "");

        holder.show_name.setText(model.getName());
        holder.show_message.setText(phoneNo);
        holder.notific.setVisibility(View.GONE);
        holder.accReq.setVisibility(View.GONE);
        holder.sendReq.setVisibility(View.GONE);
        holder.timeLast.setVisibility(View.GONE);
        holder.img_on.setVisibility(View.GONE);

       Query query = userRef.orderByChild("phno").equalTo(phoneNo);
       query.addValueEventListener(new ValueEventListener() {
           @Override
           public void onDataChange(@NonNull DataSnapshot snapshot) {
               if (!snapshot.exists()){
                   holder.itemView.getLayoutParams().height = 0;
                   holder.itemView.setVisibility(View.GONE);
               }else {
                   // want to get the userID to perform some click events.
               }
           }

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

           }
       });
    }

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

    public class ViewHolder extends RecyclerView.ViewHolder{

        public TextView show_message, show_name, timeLast;
        public ImageView personAvatarR, sendReq;
        public CircleImageView img_on,notific;
        public Button accReq;

        public ViewHolder(@NonNull View itemView) {
            super(itemView);
            accReq = itemView.findViewById(R.id.accReq);
            show_message = itemView.findViewById(R.id.personHolderEmail);
            show_name = itemView.findViewById(R.id.personHolderName);
            personAvatarR = itemView.findViewById(R.id.personAvatar);
            timeLast = itemView.findViewById(R.id.timeLast);
            img_on = itemView.findViewById(R.id.img_on);
            notific = itemView.findViewById(R.id.notific);
            sendReq = itemView.findViewById(R.id.sendReq);
        }
    }
}

contactactivity中的getcontactlist（）方法

private void getContactList() {
        Uri uri = ContactsContract.Contacts.CONTENT_URI;
        String sort = ContactsContract.CommonDataKinds.Phone.DISPLAY_NAME+" ASC";
        Cursor cursor = getContentResolver().query(
                uri,null,null,null,sort
        );
        if (cursor.getCount()>0){
            while (cursor.moveToNext()){
                String id = cursor.getString(cursor.getColumnIndex(ContactsContract.Contacts._ID));
                String name = cursor.getString(cursor.getColumnIndex(ContactsContract.Contacts.DISPLAY_NAME));

                Uri uriPhone = ContactsContract.CommonDataKinds.Phone.CONTENT_URI;
                String selection = ContactsContract.CommonDataKinds.Phone.CONTACT_ID+" =?";

                Cursor  phoneCursor = getContentResolver().query(
                        uriPhone,null,selection,new String[]{id}, null
                );

                if (phoneCursor.moveToNext()){
                    String number = phoneCursor.getString(phoneCursor.getColumnIndex(
                            ContactsContract.CommonDataKinds.Phone.NUMBER
                    ));

                    Contacts model = new Contacts();
                    model.setName(name);
                    model.setNumber(number);
                    arrayList.add(model);
                    phoneCursor.close();
                }
            }
            cursor.close();
        }
        contactList.setLayoutManager(new LinearLayoutManager(this));
        adapter = new ContactsAdapter(this, arrayList);
        contactList.setAdapter(adapter);
    }