Hi

import java.util.Scanner;

public class ConsumerApp {
private static Consumer registeredConsumer = null;

public static void main(String[] args) {
    Scanner scanner = new Scanner(System.in);
    while (true) {
        if (registeredConsumer == null) {
            System.out.println("1. Register");
            System.out.println("2. Login");
            System.out.println("3. Exit");
            System.out.print("Choose an option: ");
            int choice = scanner.nextInt();
            scanner.nextLine();  // Consume newline

            switch (choice) {
                case 1:
                    registeredConsumer = register(scanner);
                    break;
                case 2:
                    if (login(scanner)) {
                        showHomePage(scanner);
                    } else {
                        System.out.println("Invalid credentials.");
                    }
                    break;
                case 3:
                    System.exit(0);
                default:
                    System.out.println("Invalid option, try again.");
            }
        } else {
            showHomePage(scanner);
        }
    }
}

private static Consumer register(Scanner scanner) {
    System.out.println("== Consumer Registration ==");
    System.out.print("Consumer ID (13 digits): ");
    String consumerId = scanner.nextLine();

    System.out.print("Bill Number (5 digits): ");
    String billNumber = scanner.nextLine();

    System.out.print("Title (Mr/Ms/Mrs/Dr): ");
    String title = scanner.nextLine();

    System.out.print("Customer Name: ");
    String customerName = scanner.nextLine();

    System.out.print("Email: ");
    String email = scanner.nextLine();

    System.out.print("Country Code: ");
    String countryCode = scanner.nextLine();

    System.out.print("Mobile Number (10 digits): ");
    String mobileNumber = scanner.nextLine();

    System.out.print("User ID: ");
    String userId = scanner.nextLine();

    System.out.print("Password: ");
    String password = scanner.nextLine();

    System.out.print("Confirm Password: ");
    String confirmPassword = scanner.nextLine();

    if (!password.equals(confirmPassword)) {
        System.out.println("Passwords do not match. Please try again.");
        return null;
    }

    Consumer consumer = new Consumer(consumerId, billNumber, title, customerName, email, countryCode, mobileNumber, userId, password);
    System.out.println("Registration successful.");
    System.out.println("Customer ID: " + consumer.getConsumerId());
    System.out.println("Customer Name: " + consumer.getCustomerName());
    System.out.println("Email: " + consumer.getEmail());

    return consumer;
}

private static boolean login(Scanner scanner) {
    System.out.println("== Login ==");
    System.out.print("User ID: ");
    String userId = scanner.nextLine();

    System.out.print("Password: ");
    String password = scanner.nextLine();

    return registeredConsumer != null && registeredConsumer.getUserId().equals(userId) && registeredConsumer.getPassword().equals(password);
}

private static void showHomePage(Scanner scanner) {
    while (true) {
        System.out.println("== Home ==");
        System.out.println("Welcome, " + registeredConsumer.getCustomerName());
        System.out.println("1. Pay Bill");
        System.out.println("2. Register Complaint");
        System.out.println("3. Complaint Status");
        System.out.println("4. Logout");

        System.out.print("Choose an option: ");
        int choice = scanner.nextInt();
        scanner.nextLine();  // Consume newline

        switch (choice) {
            case 1:
                payBill(scanner);
                break;
            case 2:
                registerComplaint(scanner);
                break;
            case 3:
                viewComplaintStatus(scanner);
                break;
            case 4:
                registeredConsumer = null;
                return;
            default:
                System.out.println("Invalid option, try again.");
        }
    }
}

private static void payBill(Scanner scanner) {
    System.out.println("== Pay Bill ==");
    System.out.print("Enter the amount to pay: ");
    double amount = scanner.nextDouble();
    scanner.nextLine();  // Consume newline

    System.out.print("Enter Payment Method (Credit/Debit): ");
    String paymentMethod = scanner.nextLine();

    System.out.println("Payment successful. Amount: $" + amount);
}

private static void registerComplaint(Scanner scanner) {
    System.out.println("== Register Complaint ==");
    System.out.print("Complaint Type (e.g., Billing, Voltage): ");
    String complaintType = scanner.nextLine();

    System.out.print("Description: ");
    String description = scanner.nextLine();

    System.out.println("Complaint registered successfully. Complaint Type: " + complaintType);
}

private static void viewComplaintStatus(Scanner scanner) {
    System.out.println("== Complaint Status ==");
    System.out.println("All complaints are resolved.");
}

}

class Consumer {
private String consumerId;
private String billNumber;
private String title;
private String customerName;
private String email;
private String countryCode;
private String mobileNumber;
private String userId;
private String password;

public Consumer(String consumerId, String billNumber, String title, String customerName, String email, String countryCode, String mobileNumber, String userId, String password) {
    this.consumerId = consumerId;
    this.billNumber = billNumber;
    this.title = title;
    this.customerName = customerName;
    this.email = email;
    this.countryCode = countryCode;
    this.mobileNumber = mobileNumber;
    this.userId = userId;
    this.password = password;
}

public String getConsumerId() {
    return consumerId;
}

public String getBillNumber() {
    return billNumber;
}

public String getTitle() {
    return title;
}

public String getCustomerName() {
    return customerName;
}

public String getEmail() {
    return email;
}

public String getCountryCode() {
    return countryCode;
}

public String getMobileNumber() {
    return mobileNumber;
}

public String getUserId() {
    return userId;
}

public String getPassword() {
    return password;
}

}