Question 343676 in Firebase Question posted in
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Firebase Recycle View is not showing data only blank dull white background in Android Studio

I following this Tutorial series on building chat app in android studio and I build a recycle view attached with Firebase database but It’s not showing up. You can see in this image, It only shows the area recycle view takes in dull white instead of showing list.

Here is my Firebase database view:
Firebase database structure

Realtime-database image Realtime-database image

Authentication tab image Authentication data image

// In MainActivity
DatabaseReference reference = database.getReference().child("User"); 


// in Register.java
    String id = task.getResult().getUser().getUid();
    DatabaseReference reference = database.getReference().child("user").child(id);
    StorageReference storageReference = storage.getReference().child("upload").child(id);

Here is: MainActivity.java: Where Recycle View is Present

package com.example.javamassenger;
import androidx.annotation.NonNull;
import androidx.appcompat.app.AppCompatActivity;
import androidx.recyclerview.widget.LinearLayoutManager;
import androidx.recyclerview.widget.RecyclerView;
import android.content.Intent;
import android.os.Bundle;
import com.google.firebase.Firebase;
import com.google.firebase.auth.FirebaseAuth;
import com.google.firebase.database.DataSnapshot;
import com.google.firebase.database.DatabaseError;
import com.google.firebase.database.DatabaseReference;
import com.google.firebase.database.FirebaseDatabase;
import com.google.firebase.database.ValueEventListener;
import java.util.ArrayList;

public class MainActivity extends AppCompatActivity {

FirebaseAuth auth;
RecyclerView UserRecyclerView;
userAdapter adapter;
FirebaseDatabase database;
ArrayList<Users> arrayList;

@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_main);

    database = FirebaseDatabase.getInstance();
    
    DatabaseReference reference = database.getReference().child("User");
    auth = FirebaseAuth.getInstance();


    arrayList = new ArrayList<>();
   
    reference.addValueEventListener(new ValueEventListener() {
        @Override
        public void onDataChange(@NonNull DataSnapshot snapshot) {

            for(DataSnapshot dataSnapshot: snapshot.getChildren())
            {
                Users users = dataSnapshot.getValue(Users.class);
                // adding data in array
                arrayList.add(users);
                Toast.makeText(MainActivity.this, "It's working", Toast.LENGTH_SHORT).show();
            }

            adapter.notifyDataSetChanged();
        }

        @Override
        public void onCancelled(@NonNull DatabaseError error) {
            Toast.makeText(MainActivity.this, "Can't Access Data", Toast.LENGTH_SHORT).show();
        }
    });

    
    UserRecyclerView = findViewById(R.id.mainUserRecyclerView);
    UserRecyclerView.setLayoutManager(new LinearLayoutManager(this));

    adapter = new userAdapter(MainActivity.this, arrayList);
    UserRecyclerView.setAdapter(adapter);

}
}

Here is: Adapter as userAdapter.java

package com.example.javamassenger;
import android.content.Context;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;
import androidx.recyclerview.widget.RecyclerView;
import com.squareup.picasso.Picasso;
import java.util.ArrayList;
import de.hdodenhof.circleimageview.CircleImageView;

public class userAdapter extends RecyclerView.Adapter<userAdapter.viewholder>{

Context mainActivity;
ArrayList<Users> arrayList;

public userAdapter(MainActivity mainActivity, ArrayList<Users> arrayList) {
    this.mainActivity = mainActivity;
    this.arrayList = arrayList;
}

@NonNull
@Override
public userAdapter.viewholder onCreateViewHolder(@NonNull ViewGroup parent, int viewType) {
    View view = LayoutInflater.from(mainActivity).inflate(R.layout.users_item, parent,false);
    return new viewholder(view);
}


@Override
public void onBindViewHolder(@NonNull userAdapter.viewholder holder, int position) {


    Users users = arrayList.get(position);
    holder.username.setText(String.valueOf(users.userName));
    holder.status.setText(String.valueOf(users.status));
    Picasso.get().load(users.profilepic).into(holder.circleImageView);
}


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


public class viewholder extends RecyclerView.ViewHolder {

    CircleImageView circleImageView;
    TextView status, username;

    public viewholder(@NonNull View itemView) {
        super(itemView);

        circleImageView = itemView.findViewById(R.id.cirImg);
        status = itemView.findViewById(R.id.status);
        username = itemView.findViewById(R.id.username);

    }
}
}

Setters & Geters Class For Array: Users.java

public class Users {
String profilepic, mail, userName, password, userId, lastMessage, status;

public Users(){}
public Users(String userId, String userName, String mail, String password, String profilepic, String status) {
    this.userId = userId;
    this.userName = userName;
    this.mail = mail;
    this.password = password;
    this.profilepic = profilepic;
    this.status = status;
}

public String getProfilepic() {
    return profilepic;
}

public void setProfilepic(String profilepic) {
    this.profilepic = profilepic;
}

public String getMail() {
    return mail;
}

public void setMail(String mail) {
    this.mail = mail;
}

public String getUserName() {
    return userName;
}

public void setUserName(String userName) {
    this.userName = userName;
}

public String getPassword() {
    return password;
}

public void setPassword(String password) {
    this.password = password;
}

public String getUserId() {
    return userId;
}

public void setUserId(String userId) {
    this.userId = userId;
}

public String getLastMessage() {
    return lastMessage;
}

public void setLastMessage(String lastMessage) {
    this.lastMessage = lastMessage;
}

public String getStatus() {
    return status;
}

public void setStatus(String status) {
    this.status = status;
}
}

MainActivity XML file activity_main.xml

<?xml version="1.0" encoding="utf-8"?>
<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:app="http://schemas.android.com/apk/res-auto"
xmlns:tools="http://schemas.android.com/tools"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:background="@drawable/mainback"
tools:context=".MainActivity">

<LinearLayout
    android:id="@+id/toolBar"
    android:layout_width="wrap_content"
    android:layout_height="@dimen/_55sdp"
    android:layout_alignParentStart="true"
    android:layout_alignParentLeft="true"
    android:layout_alignParentEnd="true"
    android:layout_alignParentRight="true"
    android:layout_marginStart="@dimen/_23sdp"
    android:layout_marginLeft="@dimen/_22sdp"
    android:layout_marginTop="@dimen/_12sdp"
    android:layout_marginEnd="@dimen/_26sdp"
    android:layout_marginRight="@dimen/_25sdp"
    android:background="@color/white"
    android:gravity="right">

</LinearLayout>

<androidx.recyclerview.widget.RecyclerView
    android:id="@+id/mainUserRecyclerView"
    android:layout_width="334dp"
    android:layout_height="330dp"
    android:layout_below="@id/toolBar"
    android:layout_alignParentStart="true"
    android:layout_alignParentLeft="true"
    android:layout_alignParentRight="true"
    android:layout_alignParentEnd="true"
    android:layout_alignParentBottom="true"
    android:layout_marginStart="13dp"
    android:layout_marginTop="160dp"
    android:layout_marginEnd="12dp"
    android:layout_marginBottom="107dp" />

users_items.xml layout view for recycle view to show items

<?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"
android:background="@drawable/bordermain"
android:layout_margin="13.00dp">

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

    <de.hdodenhof.circleimageview.CircleImageView
        android:id="@+id/cirImg"
        android:layout_width="114dp"
        android:layout_height="80dp"
        android:layout_marginStart="13.00dp"
        android:layout_marginTop="13.00dp"
        android:layout_marginEnd="13.00dp"
        android:layout_marginBottom="@dimen/_10sdp"
        android:src="@drawable/photocamera" />
    <LinearLayout
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:orientation="vertical"
        android:gravity="center">

        <TextView
            android:id="@+id/username"
            android:layout_width="match_parent"
            android:layout_height="wrap_content"
            android:fontFamily="@font/poppins_bold"
            android:text="Name"
            android:textColor="@color/black"
            android:textSize="23.40dp"/>
        
        <TextView
            android:id="@+id/status"
            android:layout_width="match_parent"
            android:layout_height="wrap_content"
            android:textColor="@color/black"
            android:fontFamily="@font/poppins_regular"
            android:textSize="10.40dp"
            android:text="Status"/>

    </LinearLayout>

</LinearLayout>

</RelativeLayout>

If anything else is need to understand problem properly please ask. Any help is appreciated.

Tags:

2

Answers


  1. 0

    You are updating your array list which is present as a variable inside your MainActivity.java. That update is not noticed by the adapter. Either make a function inside the adapter which takes that updated array list and updates the list (which is local to the adapter) and then calls notifyDataSetChanged.
    Or reinitialize your adapter every time your arrayList is updated, which is not a better way to do it. I recommend using the first approach.

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  2. 0

    The problem lies in the following line of code:

    DatabaseReference reference = database.getReference().child("User");

    Where your child is called User, with capital U, while in your database, is written in lowercase:

    enter image description here

    To solve this, simply change the starting letter to u:

    DatabaseReference reference = database.getReference().child("user");
//                                                          👆
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