parkinglot

Parking Lot System (LLD)

Problem Statement

Design and implement a Parking Lot Management System that supports parking and unparking of vehicles, parkingTicket generation, fee calculation, and management of multiple floors and spot types.

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Requirements

• Multiple Floors: The parking lot can have multiple floors.
• Parking Spots: Each floor has multiple parking spots of different types (e.g., car, bike, truck).
• Vehicle Types: Support for different vehicle types (see vehicletype/).
• Ticketing: Generate a parkingTicket when a vehicle is parked.
• Unparking: Allow vehicles to unpark and calculate the parking fee.
• Fee Calculation: Support for different fee strategies (see fee/).
• Spot Allocation: Allocate the nearest available spot of the correct type.
• Extensibility: Easy to add new vehicle types, spot types, or fee strategies.

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Core Entities

• ParkingLot: Main class managing the entire parking lot, floors, and overall operations.
• ParkingFloor: Represents a single floor in the parking lot, manages its spots.
• ParkingSpot: Represents an individual parking spot, knows its type and occupancy.
• Ticket: Represents a parking parkingTicket issued when a vehicle is parked.
• VehicleType (in vehicletype/): Enum or classes for different vehicle types.
• Fee Calculation (in fee/): Classes for calculating parking fees based on duration and vehicle type.

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Class Design

UML Class Diagram

1. ParkingLot

• Methods:
  • parkVehicle(Vehicle vehicle)
  • unparkVehicle(String ticketId)
  • addFloor(ParkingFloor floor)
  • getAvailableSpots()
• Fields: List of floors, mapping of tickets, etc.

2. ParkingFloor

• Methods:
  • getAvailableSpot(VehicleType type)
  • parkVehicle(Vehicle vehicle)
  • unparkVehicle(String spotId)
• Fields: List of spots, floor number.

3. ParkingSpot

• Methods:
  • isAvailable()
  • assignVehicle(Vehicle vehicle)
  • removeVehicle()
• Fields: Spot ID, type, current vehicle.

4. Ticket

• Fields: Ticket ID, vehicle info, entry time, spot info.

5. VehicleType (in vehicletype/)

• Enum or classes for vehicle types (Car, Bike, Truck, etc.)

6. Fee Calculation (in fee/)

• Methods: calculateFee(Ticket parkingTicket, Date exitTime)
• Extensible: Add new strategies for fee calculation.

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Design Patterns Used

• Strategy Pattern: For fee calculation strategies.
• Factory Pattern: (If used) For creating vehicles or spots.
• Singleton Pattern: (If used) For ParkingLot instance.

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Example Usage

ParkingLot lot = new ParkingLot();
lot.addFloor(new ParkingFloor(...));
Ticket parkingTicket = lot.parkVehicle(new Car("KA-01-1234"));
lot.unparkVehicle(parkingTicket.getId());

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Demo

See ParkingLotDemo.java for a sample usage of the parking lot system.

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Extending the Framework

• Add a new vehicle type: Update or add to vehicletype/.
• Add a new fee strategy: Implement a new class in fee/.
• Add new spot types or floors: Extend ParkingSpot or ParkingFloor.

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