Here's an outline of the Java interfaces and classes for the core building blocks:

1. User Authentication and Registration:

 
 public interface UserAuthentication {
    boolean registerUser(User user);
    User login(String username, String password);
    User getUserProfile(int userId);
}

 
public class User {
    private int userId;
    private String username;
    private String password;
    // Other user-related attributes, getters, and setters
}

# Station Manager

 public interface StationManager {
    Station getStationById(int stationId);
    List<Station> getAllStations();
    void addBicyclesToStation(int stationId, List<Bicycle> bicycles);
    void removeBicyclesFromStation(int stationId, List<Bicycle> bicycles);
    void configureStation(Station station);
}

 public class Station {
    private int stationId;
    private String stationName;
    private int capacity;
    private Location location;
    // Other station-related attributes, getters, and setters
}

# Bicycle Manager

public interface BicycleManager {
    Bicycle getBicycleById(int bikeId);
    List<Bicycle> getAllBicycles();
    void configureBicycle(Bicycle bicycle);
}

**Class**:

public class Bicycle {
private int bikeId;
private String serialNumber;
private String model;
private BicycleStatus status;
private Location location;
// Other bicycle-related attributes, getters, and setters
}

public enum BicycleStatus {
AVAILABLE,
RENTED,
MAINTENANCE,
}

**Class**:

public class Booking {
private int bookingId;
private User user;
private Bicycle bicycle;
private LocalDateTime startTime;
private LocalDateTime endTime;
// Other booking-related attributes, getters, and setters
}

public interface UserInterface {
List<Bicycle> getAvailableBicycles();
Booking createBooking(User user, Bicycle bicycle);
void returnBicycle(Booking booking);
}

#  Payment Gateway:

public interface PaymentGateway {
boolean processPayment(User user, double amount);
}