Class Diagram – Car Parking 

A Class Diagram models the static structure of the system by representing classes, their attributes, methods, and relationships. It helps students understand object-oriented principles such as inheritance, composition, and associations in the context of the Car Parking domain.

1. Major Classes and Their Responsibilities

Below are the core classes identified in a typical Car Parking System:

A. ParkingLot

Attributes:

• lotId: int
• location: String
• capacity: int
• availableSlots: int

Methods:

• getAvailableSlots(): int
• updateSlotAvailability(): void

B. ParkingSlot

Attributes:

• slotId: int
• isOccupied: boolean
• vehicleType: String
• floorNumber: int

Methods:

• assignVehicle(vehicle: Vehicle): void
• vacateSlot(): void

C. Vehicle

Attributes:

• vehicleNumber: String
• ownerName: String
• vehicleType: String

Methods:

• getDetails(): String

D. Ticket

Attributes:

• ticketId: int
• entryTime: DateTime
• exitTime: DateTime
• slot: ParkingSlot
• vehicle: Vehicle

Methods:

• calculateDuration(): int
• generateTicket(): void

E. Payment

Attributes:

• paymentId: int
• ticket: Ticket
• amount: double
• paymentMethod: String
• paymentStatus: String

Methods:

• processPayment(): boolean
• generateReceipt(): String

F. User (Abstract Class)

Attributes:

• userId: int
• name: String
• contactInfo: String

Methods:

• login(): boolean

G. Driver (Extends User)

Attributes:

• membershipId: String

Methods:

• requestSlot(): Ticket
• payForParking(): Payment

H. Admin (Extends User)

Methods:

• configureRates(): void
• generateReports(): List
• monitorLotStatus(): void

I. Sensor

Attributes:

• sensorId: int
• type: String (e.g., motion, barrier)
• status: boolean

Methods:

• detectVehicle(): boolean
• updateSystem(): void

2. Relationships Between Classes

• ParkingLot contains multiple ParkingSlots (Composition)
• ParkingSlot has one Vehicle (Aggregation)
• Vehicle is associated with one Ticket
• Ticket is linked to one Payment
• User is the base class for both Driver and Admin (Inheritance)
• Sensor interacts with ParkingSlot and ParkingLot

3. How to Explain This in Class

• Start by identifying real-world entities and map them to classes.
• Explain attributes as properties and methods as behaviors.
• Emphasize relationships like composition (ParkingLot → ParkingSlot) and inheritance (User → Driver/Admin).
• Demonstrate how new classes can be easily added without breaking existing design (Open/Closed Principle).
• Optionally, draw the UML diagram using boxes and arrows to visually reinforce the structure.