Generate Random Phone Numbers in Java

import java.util.ArrayList;
import java.util.List;
import java.util.Random;
import java.util.regex.Pattern;

public class PhoneNumberGenerator {
    private static final Random random = new Random();

    // Generate random US phone number (xxx) xxx-xxxx
    public static String randomUsPhoneNumber() {
        int areaCode = random.nextInt(800) + 200;
        int exchange = random.nextInt(800) + 200;
        int lineNumber = random.nextInt(9000) + 1000;
        return String.format("(%03d) %03d-%04d", areaCode, exchange, lineNumber);
    }

    // Generate random phone number with country code
    public static String randomInternationalPhone(String countryCode) {
        int areaCode = random.nextInt(800) + 200;
        int exchange = random.nextInt(800) + 200;
        int lineNumber = random.nextInt(9000) + 1000;
        return String.format("%s (%03d) %03d-%04d", countryCode, areaCode, exchange, lineNumber);
    }

    // Generate phone number without formatting
    public static String randomPhoneDigits(int length) {
        StringBuilder phone = new StringBuilder();
        for (int i = 0; i < length; i++) {
            phone.append(random.nextInt(10));
        }
        return phone.toString();
    }

    // Validate US phone number format
    public static boolean isValidUsPhone(String phone) {
        return Pattern.matches("^\(\d{3}\) \d{3}-\d{4}$", phone);
    }

    // Generate multiple phone numbers
    public static List<String> generatePhoneNumbers(int count) {
        List<String> phones = new ArrayList<>();
        for (int i = 0; i < count; i++) {
            phones.add(randomUsPhoneNumber());
        }
        return phones;
    }

    // Using JavaFaker library (Maven: com.github.javafaker:javafaker:1.0.2)
    // import com.github.javafaker.Faker;
    // Faker faker = new Faker();
    // String phone = faker.phoneNumber().phoneNumber(); // (555) 123-4567
    // String cellPhone = faker.phoneNumber().cellPhone(); // 555-123-4567

    public static void main(String[] args) {
        System.out.println("US Phone: " + randomUsPhoneNumber());
        System.out.println("International: " + randomInternationalPhone("+44"));
        System.out.println("Digits only: " + randomPhoneDigits(10));
        System.out.println("Valid: " + isValidUsPhone("(555) 123-4567"));
        System.out.println("Batch: " + String.join(", ", generatePhoneNumbers(3)));
    }
}