Create a Recycler View with Firebase Realtime Database

Create a Recycler View with Firebase Realtime Database

In this, we create a recycler view to show our fetched data from the firebase realtime database.

For reference of Firebase Realtime Database, Click here

For that,

• Import recycler view library
• Create a recycler view in XML
• An adapter class to setup recycler view
• Model class to interact with firebase database values
• Set adpater on recycler view in java file.

Recycler view library in gradle file

app-level build.gradle

 implementation 'com.android.support:recyclerview-v7:29.0.0'  

Then we create a Recycler view in XML file.

XML file

 <?xml version="1.0" encoding="utf-8"?>  
 <LinearLayout 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="wrap_content"  
   android:orientation="vertical"  
   android:layout_weight="2"  
   android:padding="10dp"  
   tools:context=".MainActivity">  
   
   <EditText  
     android:layout_width="match_parent"  
     android:layout_height="wrap_content"  
     android:hint="Roll No"  
     android:id="@+id/student_roll"/>  
   <EditText  
     android:layout_width="match_parent"  
     android:layout_height="wrap_content"  
     android:hint="Name"  
     android:id="@+id/student_name"/>  
   <EditText  
     android:layout_width="match_parent"  
     android:layout_height="wrap_content"  
     android:hint="Std"  
     android:id="@+id/student_std"/>  
   
   <Button  
     android:layout_width="match_parent"  
     android:layout_height="wrap_content"  
     android:text="Add Student"  
     android:id="@+id/add_btn"/>  
   
   <LinearLayout  
     android:layout_width="match_parent"  
     android:layout_height="wrap_content"  
     android:layout_weight="2"  
     android:orientation="vertical">  
   
     <androidx.recyclerview.widget.RecyclerView  
       android:id="@+id/student_recycler_view"  
       android:layout_width="match_parent"  
       android:layout_height="wrap_content"  
       android:padding="5dp"  
       android:scrollbars="vertical"/>  
   
   </LinearLayout>  
 </LinearLayout>  

Then we create an adapter class that extends recycler view

adapter class

 package studio.harpreet.firebaseui;  
      
 import android.app.Activity;  
 import android.app.AlertDialog;  
 import android.content.Context;  
 import android.content.DialogInterface;  
 import android.view.LayoutInflater;  
 import android.view.View;  
 import android.view.ViewGroup;  
 import android.widget.ArrayAdapter;  
 import android.widget.EditText;  
 import android.widget.LinearLayout;  
 import android.widget.TextView;  
 import android.widget.Toast;  
   
 import androidx.annotation.NonNull;  
 import androidx.annotation.Nullable;  
 import androidx.recyclerview.widget.RecyclerView;  
   
 import com.google.firebase.database.FirebaseDatabase;  
   
 import java.util.List;  
   
 public class Student_ListAdaptor extends RecyclerView.Adapter<Student_ListAdaptor.Student_Model_Holder>  
 {  
   
   Context mctx;  
   List<StudentModel> student_list;  
   
   public Student_ListAdaptor(Context mctx, List<StudentModel> student_list) {  
     this.mctx = mctx;  
     this.student_list = student_list;  
   }  
   
   @NonNull  
   @Override  
   public Student_Model_Holder onCreateViewHolder(@NonNull ViewGroup parent, int viewType) {  
   
     View view = LayoutInflater.from(parent.getContext()).inflate(R.layout.student_custom_list,parent,false);  
   
     return new Student_Model_Holder(view);  
   }  
   
   @Override  
   public void onBindViewHolder(@NonNull Student_Model_Holder holder, int position) {  
   
     holder.rolltextview.setText(String.format("Roll No: %s", studentModel.rollno));  
     holder.nametextview.setText(String.format("Name: %s", studentModel.name));  
     holder.stdtextview.setText(String.format("Std: %s", studentModel.std));  
   
   }  
   
   @Override  
   public int getItemCount() {  
     return student_list.size();  
   }  
   
   public class Student_Model_Holder extends RecyclerView.ViewHolder {  
   
     TextView rolltextview,nametextview,stdtextview;  
   
     public Student_Model_Holder(@NonNull View itemView) {  
       super(itemView);  
   
       rolltextview = itemView.findViewById(R.id.roll_textview);  
       nametextview = itemView.findViewById(R.id.name_textview);  
       stdtextview = itemView.findViewById(R.id.std_textview);  
   
     }  
   }  
 }  

and in our java file, we will create a recycler view instance and also create an adapter class instance and set that adapter on recycler view. Whenever you want to update your recycler view, just call adapter.notifydatasetchanged();

Java file

 package studio.harpreet.firebaseui;  
   
 import android.content.DialogInterface;  
 import android.content.Intent;  
 import android.os.Bundle;  
 import android.view.View;  
 import android.widget.AdapterView;  
 import android.widget.Button;  
 import android.widget.EditText;  
 import android.widget.LinearLayout;  
 import android.widget.ListView;  
 import android.widget.Toast;  
   
 import androidx.annotation.NonNull;  
 import androidx.annotation.Nullable;  
 import androidx.appcompat.app.AlertDialog;  
 import androidx.appcompat.app.AppCompatActivity;  
 import androidx.recyclerview.widget.LinearLayoutManager;  
 import androidx.recyclerview.widget.RecyclerView;  
   
 import com.google.firebase.auth.FirebaseAuth;  
 import com.google.firebase.database.ChildEventListener;  
 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.Query;  
 import com.google.firebase.database.ValueEventListener;  
   
 import java.util.ArrayList;  
 import java.util.List;  
   
 public class MainActivity extends AppCompatActivity {  
   DatabaseReference databasestudent;  
   
   EditText roll_et,name_et,std_et;  
   Button add_btn;  
   
   RecyclerView recyclerView;  
   
   Student_ListAdaptor student_listAdaptor;     
   List<StudentModel > studentlist;  
   
   @Override  
   protected void onCreate(Bundle savedInstanceState) {  
     super.onCreate(savedInstanceState);  
     setContentView(R.layout.activity_main);  
   
     roll_et = findViewById(R.id.student_roll);  
     name_et = findViewById(R.id.student_name);  
     std_et = findViewById(R.id.student_std);  
   
     add_btn = findViewById(R.id.add_btn);  
   
     recyclerView = findViewById(R.id.student_recycler_view);  
     recyclerView.setHasFixedSize(true);  
     recyclerView.setLayoutManager(new LinearLayoutManager(this));  
     recyclerView.getLayoutManager().setMeasurementCacheEnabled(false);  
     studentlist = new ArrayList<>();  
   
     student_listAdaptor = new Student_ListAdaptor(this,studentlist);  
     recyclerView.setAdapter(student_listAdaptor);  
   
     databasestudent = FirebaseDatabase.getInstance().getReference("Student/3foBhguc0HK1mgjy03"); // Now this is your path  
   
     add_btn.setOnClickListener(new View.OnClickListener() {  
       @Override  
       public void onClick(View v) {  
   
        // startActivity(new Intent(MainActivity.this,About.class));  
         addstudent(roll_et.getText().toString().trim(),name_et.getText().toString().trim(),std_et.getText().toString().trim());  
   
       }  
     });    
   }  
   
   
   private void addstudent(String Rollno, String Name, String Std)  //Insert Method  
   {  
     String id = databasestudent.push().getKey();  
   
     StudentModel studentModel = new StudentModel(id,Rollno,Name,Std);  
   
     databasestudent.child(id).setValue(studentModel);  
   }  
   @Override  
   protected void onStart() {  
     super.onStart();  
   
     Query query = FirebaseDatabase.getInstance().getReference("Student/3foBhHK1mgjy03");  
   
     query.addValueEventListener(new ValueEventListener() {  
       @Override  
       public void onDataChange(@NonNull DataSnapshot dataSnapshot) {  
   
         studentlist.clear();  // because everytime when data updates in your firebase database it creates the list with updated items  
         // so to avoid duplicate fields we clear the list everytime  
         if(dataSnapshot.exists())  
         {  
           for(DataSnapshot studentsnapshot : dataSnapshot.getChildren())  
           {  
              StudentModel studentModel = studentsnapshot.getValue(StudentModel.class);  
   
              studentlist.add(studentModel);  
           }  
   
           student_listAdaptor.notifyDataSetChanged();  
         }  
   
       }  
   
       @Override  
       public void onCancelled(@NonNull DatabaseError databaseError) {  
   
       }  
     });  
   }  
 }  

 Next Post, create an item click on recycler view

 

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