[Solved] Consider a parking lot system where vehicles of different si... When a bus arrives, which sequence of method calls correctly determines if a suitable spot is available, assuming polymorphism is used? | OOP & Design Patterns

OOP & Design Patterns - Design a Parking Lot - LLD with OOP (Classes, Patterns, Extensibility)

Consider a parking lot system where vehicles of different sizes (motorcycle, car, bus) are modeled using inheritance. When a bus arrives, which sequence of method calls correctly determines if a suitable spot is available, assuming polymorphism is used?

ACall ParkingSpot.canFitVehicle() which uses instanceof checks to identify vehicle type

BCall Bus-specific method isSpotLargeEnough() bypassing polymorphism

CCall Vehicle.getSize() and compare with spot size externally in the controller

DCall Vehicle.canFitInSpot() overridden by Bus, which checks if the spot size fits a bus

Step-by-Step Solution

Solution:

Step 1: Understand polymorphism in inheritance
Vehicle subclasses override canFitInSpot() to provide specific logic.
Step 2: Evaluate method call sequences
Calling Vehicle.canFitInSpot() on a Bus instance invokes Bus's override, leveraging polymorphism.
Step 3: Analyze other options
Using instanceof (A) breaks OOP principles; external size comparison (C) violates encapsulation; Bus-specific method (D) bypasses polymorphism.
Final Answer:
Option D -> Option D
Quick Check:
Polymorphism enables dynamic method dispatch [OK]

Quick Trick: Polymorphism calls subclass overrides automatically [OK]

Common Mistakes:

MISTAKES

Using instanceof checks instead of polymorphism
Comparing sizes externally breaking encapsulation
Bypassing polymorphism with subclass-specific calls

Trap Explanation:

PITFALL

Candidates often misuse instanceof or external logic instead of relying on polymorphism.

Interviewer Note:

CONTEXT

Assesses understanding of inheritance and polymorphism in design.

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More OOP & Design Patterns Quizzes

When a bus arrives, which sequence of method calls correctly determines if a suitable spot is available, assuming polymorphism is used?

Step 1: Understand polymorphism in inheritance

Step 2: Evaluate method call sequences

Step 3: Analyze other options

Final Answer:

Quick Check:

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