newly child added data does not populate new cardview,it only updates the one existed card,so what should be changed in adapter to populate new cards

Question

so what should be changed in adapter which populates new cards when a child is added in firebase,im sending data through an object of modal class.Now its only makes 1 card on which newly added data is updated on.No new cards are being populated.and i dont want to get the whole data again and again,i just wanted to get data only one time and it should be retreived when a child is added on because the admin has to approve the patients data(and then it should be removed thereafter).

myadapter

public class Adapter extends RecyclerView.Adapter<Adapter.Viewholder> {


    public UserInformation value = new UserInformation();


    public Adapter(UserInformation value) {
        this.value = value;

    }


    @Override
    public Viewholder onCreateViewHolder(ViewGroup parent, int viewType) {
        LayoutInflater inflater = LayoutInflater.from(parent.getContext());
        View view = inflater.inflate(R.layout.item_user_layout, parent, false);
        return new Viewholder(view);

    }

    @Override
    public void onBindViewHolder(Viewholder holder, int position) {

        holder.edt_blood_group.setText(value.getBlood_group());
        holder.edt_contact_no.setText(value.getContact_no());
        holder.btn_approve.setText("approve");
    }

    @Override
    public int getItemCount() {
        return 3; //i dont know what to write here as i have no array of data
    }

    public class Viewholder extends RecyclerView.ViewHolder {
        EditText edt_blood_group;
        EditText edt_contact_no;
        Button btn_approve;

        public Viewholder(View itemView) {
            super(itemView);
            edt_blood_group = (EditText) itemView.findViewById(R.id.edt_blood_group);
            edt_contact_no = (EditText) itemView.findViewById(R.id.edt_contact_no);
             btn_approve = (Button) itemView.findViewById(R.id.btn_approve);

        }
    }
}

my MainActivity

     protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        final RecyclerView rcc = (RecyclerView) findViewById(R.id.userList);
        rcc.setLayoutManager(new LinearLayoutManager(this));
        //edtobj= (EditText) findViewById(R.id.edt_id);

        FirebaseDatabase firebaseDatabase = FirebaseDatabase.getInstance();
        DatabaseReference reference = firebaseDatabase.getReference("Patients");
        reference.addChildEventListener(new ChildEventListener() {
            @Override
            public void onChildAdded(DataSnapshot dataSnapshot, String s) {
                UserInformation newPost = dataSnapshot.getValue(UserInformation.class);
                rcc.setAdapter(new Adapter(newPost));

            }

item_layout

<android.support.v7.widget.CardView xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_width="match_parent"
    android:layout_height="wrap_content"
    android:layout_margin="8dp">

    <LinearLayout
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:orientation="vertical">

        <EditText
            android:id="@+id/edt_blood_group"
            android:layout_width="160dp"
            android:layout_height="wrap_content" />

        <EditText
            android:id="@+id/edt_contact_no"
            android:layout_width="160dp"
            android:layout_height="wrap_content" />

        <Button
            android:id="@+id/btn_approve"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:text="approve" />


    </LinearLayout>

The adapter should take user information array or arraylist... not a single item! — Xenolion, Jul 14 '18 at 08:14
and that array is supposed to have a complete snapshot of data or the last newly added data? and which listener is suitable for this purpose. — Umar Farooq Khan, Jul 14 '18 at 08:28
The array list is better if you want to be updating your data, add the data and the recycler view will appear with n+1 items each time you add. — Xenolion, Jul 14 '18 at 08:29
got it,but the data received from firebase is the "complete" snapshot of the data(whole data) everytime? or just a new child is added to the list,and that list is again populated? — Umar Farooq Khan, Jul 14 '18 at 09:33
You are getting a single snapshot each time, not a whole data! Make an array list in your adapter. Its a common and good approach! — Xenolion, Jul 14 '18 at 11:19
**[This](https://stackoverflow.com/questions/49383687/how-can-i-retrieve-data-from-firebase-to-my-adapter/49384849)** is a recommended way in which you can retrieve data from a Firebase Realtime database and display it in a `RecyclerView` using `FirebaseRecyclerAdapter`. — Alex Mamo, Jul 15 '18 at 13:18

score 0 · Answer 1 · answered Jul 14 '18 at 15:58

Do this in your main activity..!

Adapter adapter = null;
ArrayList<GetPatients> list = new ArrayList<>();
@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_data_list);
    recyclerView = findViewById(R.id.recycler_view);
    adapter = new Adapter(list);
    recyclerView.setLayoutManager(new LinearLayoutManager(this));
    recyclerView.setHasFixedSize(true);
    recyclerView.setAdapter(adapter);
    FirebaseDatabase firebaseDatabase = FirebaseDatabase.getInstance();
    DatabaseReference reference = firebaseDatabase.getReference("Patients");
    reference.addChildEventListener(this);
}

@Override
public void onChildAdded(DataSnapshot dataSnapshot,String s) {
    GetPatients value = dataSnapshot.getValue(GetPatients.class);
    list.add(new GetPatients(value.getPatientName(),value.getBloodGroup(),value.getContactNo()));
    adapter.notifyDataSetChanged();
}

@Override
public void onChildChanged(DataSnapshot dataSnapshot,String s) {

}

@Override
public void onChildRemoved(@NonNull DataSnapshot dataSnapshot) {

}

@Override
public void onChildMoved(@NonNull DataSnapshot dataSnapshot, @Nullable String s) {

}

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

}

}

newly child added data does not populate new cardview,it only updates the one existed card,so what should be changed in adapter to populate new cards

1 Answers1