frestoinc

        <service
            android:name="com.example.AuthenticatorService"
            android:enabled="true"
            android:exported="true">
            <intent-filter>
                <action android:name="android.accounts.AccountAuthenticator" />
            </intent-filter>

            <meta-data
                android:name="android.accounts.AccountAuthenticator"

frestoinc

<?xml version="1.0" encoding="utf-8"?>
<manifest xmlns:android="http://schemas.android.com/apk/res/android"
    package="com.packagename">

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

    <application

frestoinc

public class PhoneBookManager {

    private final ContentResolver contentResolver;

    public PhoneBookManager(final Context context) {
        contentResolver = context.getContentResolver();
    }

    private boolean isContactWithNumberExists(@NonNull final String number) {

frestoinc

/**
  _____        _____                  _             
 |  __ \      / ____|                | |            
 | |  | | ___| |     _ __ _   _ _ __ | |_ ___  _ __ 
 | |  | |/ _ \ |    | '__| | | | '_ \| __/ _ \| '__|
 | |__| |  __/ |____| |  | |_| | |_) | || (_) | |   
 |_____/ \___|\_____|_|   \__, | .__/ \__\___/|_|   
                           __/ | |                  
                          |___/|_|                  
 */