Set Text in Navigation drawer which is retrieve from Firebase

Question

i am trying to show Users details in Navigation Bar I've successfully retrive the value from firebase but it's not setting to the nav header textlayout. here's my navigation 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"
    android:layout_width="match_parent"
    android:layout_height="@dimen/nav_header_height"
android:background="@drawable/header"
android:gravity="bottom"
android:orientation="vertical"
android:paddingLeft="@dimen/activity_horizontal_margin"
android:paddingTop="@dimen/activity_vertical_margin"
android:paddingRight="@dimen/activity_horizontal_margin"
android:paddingBottom="@dimen/activity_vertical_margin"
android:theme="@style/ThemeOverlay.AppCompat.Dark">

<ImageView
    android:id="@+id/imageView"
    android:layout_width="80dp"
    android:layout_height="80dp"
    android:contentDescription="@string/nav_header_desc"
    android:paddingTop="@dimen/nav_header_vertical_spacing"
    app:srcCompat="@drawable/user_icon" />

<TextView
    android:id="@+id/holder_nav_text_username"
    android:layout_width="wrap_content"
    android:textSize="14sp"
    android:layout_height="wrap_content"
    android:textColor="#ffffff"
    android:paddingTop="@dimen/nav_header_vertical_spacing"
    android:textAppearance="@style/TextAppearance.AppCompat.Body1" />

<TextView
    android:id="@+id/holder_nav_text_email"
    android:textColor="#ffffff"
    android:layout_width="wrap_content"
    android:layout_height="wrap_content" />
<TextView
    android:id="@+id/holder_nav_text_phone"
    android:textColor="#ffffff"
    android:layout_width="wrap_content"
    android:layout_height="wrap_content" />

and here's my java class of main activity which contains navigation header .

    package com.example.closeup;

import android.os.Bundle;

import com.google.android.material.floatingactionbutton.FloatingActionButton;
import com.google.android.material.snackbar.Snackbar;

import android.view.View;

import androidx.annotation.NonNull;
import androidx.annotation.Nullable;
import androidx.navigation.NavController;
import androidx.navigation.Navigation;
import androidx.navigation.ui.AppBarConfiguration;
import androidx.navigation.ui.NavigationUI;

import com.google.android.material.navigation.NavigationView;
import com.google.firebase.auth.FirebaseAuth;
import com.google.firebase.auth.FirebaseUser;
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 androidx.drawerlayout.widget.DrawerLayout;

import androidx.appcompat.app.AppCompatActivity;
import androidx.appcompat.widget.Toolbar;

import android.view.Menu;
import android.widget.TextView;
import android.widget.Toast;

public class Dashboard extends AppCompatActivity {

    private AppBarConfiguration mAppBarConfiguration;
    FirebaseUser fuser;
    DatabaseReference dref,dr;
    String uid;

    TextView r_username,r_email,r_phone;


    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_interface);
        Toolbar toolbar = findViewById(R.id.toolbar);
        setSupportActionBar(toolbar);
        FloatingActionButton fab = findViewById(R.id.fab);

        fuser= FirebaseAuth.getInstance().getCurrentUser();
        uid=fuser.getUid();
        dref= FirebaseDatabase.getInstance().getReference("Users");


        r_username=findViewById(R.id.holder_nav_text_username);
        r_email=findViewById(R.id.holder_nav_text_email);
        r_phone=findViewById(R.id.holder_nav_text_phone);





        dref.addListenerForSingleValueEvent(new ValueEventListener() {
            @Override
            public void onDataChange(@NonNull DataSnapshot dataSnapshot) {
                String c_username=dataSnapshot.child(uid).child("name").getValue(String.class);
                String c_email=dataSnapshot.child(uid).child("email").getValue(String.class);
                String c_phone=dataSnapshot.child(uid).child("phone").getValue(String.class);

                Toast.makeText(getApplicationContext(),"Your ID: " + uid,Toast.LENGTH_SHORT).show();
                Toast.makeText(getApplicationContext(),"Your Name: " + c_username,Toast.LENGTH_SHORT).show();
                Toast.makeText(getApplicationContext(),"Your email: " + c_email,Toast.LENGTH_SHORT).show();
                Toast.makeText(getApplicationContext(),"Your phone: " + c_phone,Toast.LENGTH_SHORT).show();

            }




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

            }
        });




        fab.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View view) {
                Snackbar.make(view, "Replace with your own action", Snackbar.LENGTH_LONG)
                        .setAction("Action", null).show();
            }
        });
        DrawerLayout drawer = findViewById(R.id.drawer_layout);
        NavigationView navigationView = findViewById(R.id.nav_view);

        mAppBarConfiguration = new AppBarConfiguration.Builder(
                R.id.nav_home,R.id.nav_tools, R.id.nav_share,R.id.nav_mealentry, R.id.nav_send,R.id.nav_interfaced)
                .setDrawerLayout(drawer)
                .build();
        NavController navController = Navigation.findNavController(this, R.id.nav_host_fragment);
        NavigationUI.setupActionBarWithNavController(this, navController, mAppBarConfiguration);
        NavigationUI.setupWithNavController(navigationView, navController);
    }

    @Override
    public boolean onCreateOptionsMenu(Menu menu) {
        // Inflate the menu; this adds items to the action bar if it is present.
        getMenuInflater().inflate(R.menu.interfacee,menu);
        return true;
    }

    @Override
    public boolean onSupportNavigateUp() {
        NavController navController = Navigation.findNavController(this, R.id.nav_host_fragment);
        return NavigationUI.navigateUp(navController, mAppBarConfiguration)
                || super.onSupportNavigateUp();
    }
}

and i've tried this way.

    dref.addListenerForSingleValueEvent(new ValueEventListener() {
        @Override
        public void onDataChange(@NonNull DataSnapshot dataSnapshot) {
            String c_username=dataSnapshot.child(uid).child("name").getValue(String.class);
            String c_email=dataSnapshot.child(uid).child("email").getValue(String.class);
            String c_phone=dataSnapshot.child(uid).child("phone").getValue(String.class);

            Toast.makeText(getApplicationContext(),"Your ID: " + uid,Toast.LENGTH_SHORT).show();
            Toast.makeText(getApplicationContext(),"Your Name: " + c_username,Toast.LENGTH_SHORT).show();
            Toast.makeText(getApplicationContext(),"Your email: " + c_email,Toast.LENGTH_SHORT).show();
            Toast.makeText(getApplicationContext(),"Your phone: " + c_phone,Toast.LENGTH_SHORT).show();

            r_username.setText(c_username);
            r_email.setText(c_email);
            r_phone.setText(c_phone);


        }

in this way app got crashed. fyi without last three line i'ts shows exact data in Toast Message. now how can i show this data on navigation header text view.