contact lsit android

 package com.rscit.rscitapp.act;

import android.Manifest;
import android.annotation.SuppressLint;
import android.content.pm.PackageManager;
import android.database.Cursor;
import android.os.Bundle;
import android.provider.ContactsContract;
import android.widget.ArrayAdapter;
import android.widget.ListView;
import android.widget.Toast;

import androidx.annotation.NonNull;
import androidx.appcompat.app.AppCompatActivity;
import androidx.core.app.ActivityCompat;
import androidx.core.content.ContextCompat;

import com.rscit.rscitapp.R;

import java.io.File;
import java.io.FileWriter;
import java.io.IOException;
import java.util.ArrayList;
import java.util.HashSet;

public class ContactListActivity extends AppCompatActivity {
private static final int REQUEST_READ_CONTACTS = 79;
private ArrayList<String> contactsList;
private ListView contactsListView;

@SuppressLint("MissingInflatedId")
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_contact_list);

contactsList = new ArrayList<>();
contactsListView = findViewById(R.id.listViewContacts);

// Check permission to read contacts
if (ContextCompat.checkSelfPermission(this, Manifest.permission.READ_CONTACTS) != PackageManager.PERMISSION_GRANTED) {
ActivityCompat.requestPermissions(this, new String[]{Manifest.permission.READ_CONTACTS}, REQUEST_READ_CONTACTS);
} else {
// Permission already granted
retrieveContacts();
}
}

@Override
public void onRequestPermissionsResult(int requestCode, @NonNull String[] permissions, @NonNull int[] grantResults) {
super.onRequestPermissionsResult(requestCode, permissions, grantResults);
if (requestCode == REQUEST_READ_CONTACTS) {
if (grantResults.length > 0 && grantResults[0] == PackageManager.PERMISSION_GRANTED) {
retrieveContacts();
}
}
}

private void retrieveContacts() {
HashSet<String> uniqueNumbers = new HashSet<>();

Cursor cursor = getContentResolver().query(
ContactsContract.CommonDataKinds.Phone.CONTENT_URI,
null,
null,
null,
null
);

if (cursor != null) {
try {
File file = new File(getExternalFilesDir(null), "contact_list.txt");
FileWriter writer = new FileWriter(file);

while (cursor.moveToNext()) {
@SuppressLint("Range") String contactName = cursor.getString(cursor.getColumnIndex(ContactsContract.CommonDataKinds.Phone.DISPLAY_NAME));
@SuppressLint("Range") String contactNumber = cursor.getString(cursor.getColumnIndex(ContactsContract.CommonDataKinds.Phone.NUMBER));

// Remove any non-digit characters from the contact number
contactNumber = contactNumber.replaceAll("[^0-9]", "");

// Check if the number is unique
if (!uniqueNumbers.contains(contactNumber)) {
uniqueNumbers.add(contactNumber);
String contactEntry = contactName + " : " + contactNumber;
contactsList.add(contactEntry);
writer.write(contactEntry + "\n");
}
}

writer.close();

ArrayAdapter<String> adapter = new ArrayAdapter<>(this, android.R.layout.simple_list_item_1, contactsList);
contactsListView.setAdapter(adapter);

// Show toast with directory
String directory = file.getParent();
Toast.makeText(this, "Contact list saved in: " + directory, Toast.LENGTH_LONG).show();
} catch (IOException e) {
e.printStackTrace();
} finally {
cursor.close();
}}}@Override
public boolean onSupportNavigateUp() {
onBackPressed();
return true;
}}