Android Firestore document data show on listview

<uses-permission android:name="android.permission.INTERNET" />

<?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:orientation="vertical"
    android:layout_height="match_parent"
    tools:context=".Showlist">


    <Button
        android:id="@+id/alldata"
        android:text="Alldata"
        android:layout_width="match_parent"
        android:layout_height="wrap_content" />

    <ListView
        android:id="@+id/list"
        android:layout_width="match_parent"
        android:layout_height="match_parent"></ListView>
</LinearLayout>

package olee.tech.ngo;

import android.support.v7.app.AppCompatActivity;
import android.os.Bundle;
import android.view.View;
import android.widget.ArrayAdapter;
import android.widget.Button;
import android.widget.ListView;

import com.google.firebase.firestore.DocumentSnapshot;
import com.google.firebase.firestore.EventListener;
import com.google.firebase.firestore.FirebaseFirestore;
import com.google.firebase.firestore.FirebaseFirestoreException;
import com.google.firebase.firestore.QuerySnapshot;

import java.util.ArrayList;
import java.util.List;

import javax.annotation.Nullable;

public class Showlist extends AppCompatActivity {
private ListView list;
private Button alldata;
private List<String> mylist =new ArrayList<String>();
    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_showlist);

        list=findViewById(R.id.list);
        alldata=findViewById(R.id.alldata);
        final FirebaseFirestore db= FirebaseFirestore.getInstance();

        alldata.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
            db.collection("users").addSnapshotListener(new EventListener<QuerySnapshot>() {
                @Override
                public void onEvent(@Nullable QuerySnapshot queryDocumentSnapshots, @Nullable FirebaseFirestoreException e) {
                    mylist.clear();
                    for (DocumentSnapshot documentSnapshot:queryDocumentSnapshots){
                        mylist.add(documentSnapshot.getString("name"));
                    }

                    ArrayAdapter arrayAdapter = new ArrayAdapter(getApplicationContext(),android.R.layout.simple_list_item_1,mylist);
                    list.setAdapter(arrayAdapter);

                }
            });

            }
        });
    }
}