Firebase RecyclerView in Fragment

Question

Can anyone help with this situation? I want to show history in a recycleview in a fragment from firebase database. But doesn't show. What went wrong i can not figure out. The app works fine but showing nothing in recyclerview.

My history class

public class History {

public String Date;
public String Amount;
public String Via;
public String Mobile_Number;

public History() {
}

public History(String date, String amount, String via, String mobile_Number)  
{
    Date = date;
    Amount = amount;
    Via = via;
    Mobile_Number = mobile_Number;
}

public String getDate() {
    return Date;
}

public void setDate(String date) {
    Date = date;
}

public String getAmount() {
    return Amount;
}

public void setAmount(String amount) {
    Amount = amount;
}

public String getVia() {
    return Via;
}

public void setVia(String via) {
    Via = via;
}

public String getMobile_Number() {
    return Mobile_Number;
}

public void setMobile_Number(String mobile_Number) {
    Mobile_Number = mobile_Number;
}
}

I am using this viewholder class.

public class History {

public String Date;
public String Amount;
public String Via;
public String Mobile_Number;

public History() {
}

public History(String date, String amount, String via, String mobile_Number) 
{
    Date = date;
    Amount = amount;
    Via = via;
    Mobile_Number = mobile_Number;
}

public String getDate() {
    return Date;
}

public void setDate(String date) {
    Date = date;
}

public String getAmount() {
    return Amount;
}

public void setAmount(String amount) {
    Amount = amount;
}

public String getVia() {
    return Via;
}

public void setVia(String via) {
    Via = via;
}

public String getMobile_Number() {
    return Mobile_Number;
}

public void setMobile_Number(String mobile_Number) {
    Mobile_Number = mobile_Number;
}
}

This fragment is used on pager.

 @Override
public View onCreateView(LayoutInflater inflater, ViewGroup container,
                         Bundle savedInstanceState) {
    mMainView = inflater.inflate(R.layout.fragment_profile, container, 
false);


    recyclerView = (RecyclerView) 
mMainView.findViewById(R.id.profile_recycler);


    String uid = FirebaseAuth.getInstance().getCurrentUser().getUid();
    String email = FirebaseAuth.getInstance().getCurrentUser().getEmail();


    mDatabase = 
FirebaseDatabase.getInstance().getReference().child("Users").child(uid);
    mDatabase.keepSynced(true);



    recyclerView.setLayoutManager(new LinearLayoutManager(getActivity()));

    Query query = FirebaseDatabase.getInstance()
            .getReference()
            .child("Users").child(uid).child("History").orderByKey();

    FirebaseRecyclerOptions<History> options = new 
FirebaseRecyclerOptions.Builder<History>()
            .setQuery(query, History.class).build();

    FirebaseRecyclerAdapter adapter = new 
FirebaseRecyclerAdapter<History,HistoryViewHolder>(options) {
        @Override
        protected void onBindViewHolder(@NonNull HistoryViewHolder holder, 
int position, @NonNull History model) {
            holder.setAmountText("100");
            holder.setDateText("dd-mm-yyyy");
            holder.setMobileText("model.getMobile_Number()");
            holder.setViaText("model.getVia()");
        }


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

            return new HistoryViewHolder(view);
        }
    };

    recyclerView.setAdapter(adapter);

    return mMainView;
}

History layout to populate every data

<?xml version="1.0" encoding="utf-8"?>
<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:layout_width="match_parent"
android:layout_height="wrap_content">


<TextView
    android:id="@+id/history_date"
    android:layout_width="wrap_content"
    android:layout_height="wrap_content"
    android:layout_alignParentStart="true"
    android:layout_alignParentTop="true"
    android:layout_marginLeft="0dp"
    android:layout_marginTop="4dp"
    android:fontFamily="serif"
    android:text="Date"
    android:textColor="@color/colorPrimary"
    android:textStyle="bold" />

<TextView
    android:id="@+id/history_mobile_number"
    android:layout_width="wrap_content"
    android:layout_height="wrap_content"
    android:layout_alignTop="@+id/history_date"
    android:layout_marginStart="16dp"
    android:layout_toEndOf="@+id/history_date"
    android:text="Mobile Number" />

<TextView
    android:id="@+id/history_via"
    android:layout_width="wrap_content"
    android:layout_height="wrap_content"
    android:layout_alignStart="@+id/history_mobile_number"
    android:layout_below="@id/history_mobile_number"
    android:text="Via"
    android:textStyle="bold" />

<TextView
    android:id="@+id/history_amount"
    android:layout_width="wrap_content"
    android:layout_height="wrap_content"
    android:layout_alignStart="@+id/history_via"
    android:layout_below="@+id/history_via"
    android:layout_marginBottom="4dp"
    android:text="Taka" />
</RelativeLayout>

Answer 1

To get data you need to subscribe with

adapter.startListening();

and then unsubscribe with adapter.stopListening();

You need to start listening after you set your adapter. You can do it in onStart() method in the fragment and stop in onStop(). And before you do it add check for the adapter not being null or you may get a nullpointerexeption. This firebase adapter can be tricky. Once I tried to use it and ended up rewriting the whole thing with the regular RecyclerViewAdapter class.

Also, I see you're using the "" around the method calls. You are creating a string from this text and it won't be called as expected. Remove the ""

@Override
        protected void onBindViewHolder(@NonNull HistoryViewHolder holder, 
int position, @NonNull History model) {
            holder.setAmountText("100");
            holder.setDateText("dd-mm-yyyy");
            holder.setMobileText(model.getMobile_Number());
            holder.setViaText(model.getVia());
        }