从Firebase回收器适配器到textview的项目总数

Question

我需要从firebase recycleradapter获取组成员计数，但是我不知道该怎么做。由于我是android的新手，请帮助修复它。 我的代码可以很好地从数据库中检索所有组，但是我无法从单个组中获取成员计数并在每个组中显示它们。

每组的会员人数：

 public class JoinGroup extends AppCompatActivity {
    RecyclerView mGrouplist;
    LinearLayoutManager mLayoutManager;
    DatabaseReference mDatabase;
    String groupRef,username;
    String sub_push_Key;
    String userId;
    String groupname,groupphoto;
    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_join_group);
        mGrouplist = findViewById(R.id.grouplist);
        mGrouplist.setHasFixedSize(true);
        // mpostlist.setLayoutManager(new LinearLayoutManager(PostList.this));
        mLayoutManager = new LinearLayoutManager(this);
        mLayoutManager.setReverseLayout(false);
        mLayoutManager.setStackFromEnd(false);
        // Now set the layout manager and the adapter to the RecyclerView
        mGrouplist.setLayoutManager(mLayoutManager);
        mDatabase = FirebaseDatabase.getInstance().getReference().child("AllGroups");
        userId=FirebaseAuth.getInstance().getCurrentUser().getUid();
    }


    @Override

    public void onStart() {
        super.onStart();
        final ProgressDialog progressDialog = new ProgressDialog(this);
        progressDialog.setTitle("Loading Groups..");
        progressDialog.setMessage("Please wait..");
        progressDialog.setCancelable(false);
        progressDialog.show();

如何在此处使用getItemCount方法：

   final FirebaseRecyclerAdapter<GroupModel, JoinGroup.PostViewFolder> PSVF = new FirebaseRecyclerAdapter<GroupModel,JoinGroup.PostViewFolder>(
                GroupModel.class,
                R.layout.joingrouplayout,
                JoinGroup.PostViewFolder.class,
                mDatabase)
        {
            @Override
            protected void populateViewHolder(final JoinGroup.PostViewFolder viewHolder, final GroupModel model, final int position) {
               viewHolder.setGroupname(model.getGroupname());
                viewHolder.setImageurl(getApplicationContext(),model.getImageurl());
                progressDialog.cancel();
                final String groupKey = getRef(position).getKey();

                viewHolder.mview.setOnClickListener(new View.OnClickListener() {
                    @Override
                    public void onClick(View v) {
                        groupRef = groupKey;
                        groupname=model.getGroupname();
                        groupphoto=model.getImageurl();
                       // Toast.makeText(JoinGroup.this,"MEMBER " +String.valueOf(count),Toast.LENGTH_LONG).show();

                        joinGroup();

                    }
                });
            }
        };

        mGrouplist.setAdapter(PSVF);
    }

    public static class PostViewFolder extends RecyclerView.ViewHolder {
        View mview;
        public PostViewFolder(View itemView) {
            super(itemView);
            mview = itemView;
        }

        public void setGroupname(String groupname) {
            TextView namegroup = (TextView) mview.findViewById(R.id.groupname);
            namegroup.setText(groupname);
        }
        public void setImageurl(Context ctx, String imageurl) {
            ImageView groupimage =  mview.findViewById(R.id.groupimage);
            Glide.with(ctx)
                    .load(imageurl)
                    .into(groupimage);
            }
           }