If the parking lot system must support real-time spot availability updates and notifications to multiple display boards and mobile apps, which design pattern should be introduced to decouple the parking lot state changes from the notification logic?

hard🎤 Interviewer Follow-up Q10 of Q15

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

ASingleton pattern to centralize notification management

BObserver pattern to notify subscribers on state changes

CFactory pattern to create notification objects

DStrategy pattern to select notification channels dynamically

Step-by-Step Solution

Solution:

Step 1: Identify need for decoupling state changes and notifications
Parking lot state changes must trigger updates without tight coupling.
Step 2: Analyze pattern roles
Observer pattern allows multiple subscribers to be notified on changes; Singleton centralizes instances but doesn't handle notifications; Factory creates objects but not notification flow; Strategy selects algorithms but not event propagation.
Step 3: Select appropriate pattern
Observer pattern fits perfectly for event-driven notifications.
Final Answer:
Option B -> Option B
Quick Check:
Observer decouples event source and listeners [OK]

Quick Trick: Observer pattern decouples event and notification [OK]

Common Mistakes:

MISTAKES

Choosing Singleton for notification management
Confusing Factory with event handling
Using Strategy for event propagation

Trap Explanation:

PITFALL

Candidates confuse object creation or instance control with event notification responsibilities.

Interviewer Note:

CONTEXT

Assesses knowledge of behavioral patterns for event-driven design.

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If the parking lot system must support real-time spot availability updates and notifications to multiple display boards and mobile apps, which design pattern should be introduced to decouple the parking lot state changes from the notification logic?

Step 1: Identify need for decoupling state changes and notifications

Step 2: Analyze pattern roles

Step 3: Select appropriate pattern

Final Answer:

Quick Check:

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