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Smart Parking Management System

Course: ECOM F213 - Object Oriented Programming Project: Q4 - Smart Parking Management System

1. Project Overview

The Smart Parking Management System is a comprehensive Java-based application designed to automate the operations of a parking facility. The system manages the entire lifecycle of vehicle parking, from user registration and slot reservation to real-time vehicle entry/exit tracking and automated billing calculation.

The project was built to demonstrate robust software design principles, replacing manual tracking with a type-safe, object-oriented solution. It supports role-based access (Admins, Attendants, and Users), handles multiple vehicle types, and ensures data persistence across sessions using file I/O.

2. Object-Oriented Design Analysis

The system architecture is built upon the four pillars of Object-Oriented Programming:

• Encapsulation: All data models (e.g., User, Booking, ParkingSlot) use private fields to protect internal state. Access is controlled via public getters and setters, ensuring data integrity (e.g., a booking status cannot be changed to "COMPLETED" without passing validation checks).
• Abstraction: We utilized Interfaces (Authenticator, Payment, EntryExitHandler) and Abstract Classes (AbstractVehicle) to define contracts. This decouples the implementation details from the high-level logic.
• Inheritance: The system uses Hierarchical Inheritance to model vehicles. Car and Motorcycle classes inherit shared properties (license plate, owner) from AbstractVehicle, reducing code duplication.
• Polymorphism: The system employs Method Overloading (compile-time polymorphism) for flexibility in object creation and method calls. Additionally, the Attendant inner class demonstrates polymorphism by implementing multiple interfaces, allowing it to be treated as both a payment processor and a gate handler.

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3. Rubrics of Usage (Requirement Checklist)

The following table confirms the implementation of the 12 mandatory constraints specified in the project instructions.

#	Component Category	Implementation Details	Count	File / Location
1	Nested Classes	Used static class ParkingSlot (data) and inner class Attendant (logic).	2	ParkingSystem.java
2	Abstract Class	AbstractVehicle serves as the base template for all vehicles.	1	AbstractVehicle.java
3	Interface	Defined Authenticator, Payment, and EntryExitHandler.	3	interfaces/ package
4	Hierarchical Inheritance	Car and Motorcycle both extend AbstractVehicle.	1	model/ package
5	Multiple Inheritance	The Attendant class implements EntryExitHandler AND Payment interfaces.	1	ParkingSystem.java
6	Package	organized into com.smartpark.model, service, interfaces, util, exceptions.	5	All files
7	Exception Handling	SlotNotAvailableException (custom), IOException, NumberFormatException.	3	exceptions/, Main.java
8	I/O Operations	Scanner for CLI input, FileWriter/FileReader for booking persistence.	2	Main.java, Persistence.java
9	Overloaded Methods	addSlot(String) vs addSlot(String...); register methods.	>2	ParkingSystem.java, UserService.java
10	Overloaded Constructors	Booking and User classes have multiple constructors for flexibility.	2	Booking.java, User.java
11	Vararg Overloading	addSlot(String...) and addBookingId(int...) handle variable inputs.	2	ParkingSystem.java, User.java
12	Wrappers	Extensive use of Integer (IDs) and Double (Amounts).	Many	Booking.java, User.java

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4. Feature Implementation Snippets

1. Nested Classes

// In ParkingSystem.java
public class ParkingSystem {
    // Static Nested Class: Memory efficient for storing slot data
    public static class ParkingSlot {
        private int id;
        private String type;
        // ...
    }

    // Inner Class: Accesses outer class state for operations
    public class Attendant implements EntryExitHandler, Payment {
        // ...
    }
}

2. Abstract Class

// In AbstractVehicle.java
public abstract class AbstractVehicle {
    protected String licensePlate;
    // Abstract method forces subclasses to define their type
    public abstract String getType();
}

3. Interface

// In Authenticator.java
public interface Authenticator {
    User login(String username, String password);
}

4. Hierarchical Inheritance

// In Car.java
public class Car extends AbstractVehicle {
    public Car(String plate) { super(plate); }
    @Override
    public String getType() { return "Car"; }
}

// In Motorcycle.java
public class Motorcycle extends AbstractVehicle {
    public Motorcycle(String plate) { super(plate); }
    @Override
    public String getType() { return "Motorcycle"; }
}

5. Multiple Inheritance (via Interfaces)

// In ParkingSystem.java
// Implements methods from two distinct interfaces
public class Attendant implements EntryExitHandler, Payment {
    @Override
    public void markEntry(Booking booking) { /* Logic */ }

    @Override
    public boolean pay(Booking booking, Double amount) { /* Logic */ }
}

7. Exception Handling

// Custom Checked Exception
public class SlotNotAvailableException extends Exception {
    public SlotNotAvailableException(String message) { super(message); }
}

// Usage in ParkingSystem.java
if (slot.isOccupied()) {
    throw new SlotNotAvailableException("Slot is already occupied.");
}

8. I/O Operations

// In Persistence.java (File Handling)
try (PrintWriter pw = new PrintWriter(new FileWriter(file))) {
    pw.printf(fmt, idStr, user, slot, status, amount);
} catch (IOException e) {
    System.out.println("Error saving file");
}

9. Overloaded Methods

// In ParkingSystem.java
public void addSlot(String type) { ... } // Single
public void addSlot(String... types) { ... } // Multiple (Varargs)

10. Overloaded Constructors

// In Booking.java
public Booking(String user, int slot) { ... } // New Booking
public Booking(Integer id, String user, int slot) { ... } // Loading from File

11. Vararg Overloading

// In User.java
public void addBookingId(int... multipleBookingIds) {
    for (int id : multipleBookingIds) {
        addBookingId(id);
    }
}

12. Wrappers

// Using Integer object instead of primitive int to allow null values
private Integer bookingId; 
private Double amount;

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