Java Machine Coding: How to Design a Scalable Cab Booking System (Uber/Ola)

Designing a cab-booking system like Uber is a staple in senior machine coding rounds because it tests your ability to handle real-time state changes and extensible business logic. It’s not just about CRUD operations; it’s about how you decouple driver matching from pricing algorithms under high concurrency.

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The Mistake Most Candidates Make

Hardcoding Logic: Embedding "Nearest Driver" logic directly inside a RideService , making it impossible to swap for "Highest Rated Driver" or "Batch Matching" later.

Race Conditions: Neglecting thread safety in the ride lifecycle, allowing two drivers to accept the same ride or a rider to cancel while a driver is being assigned.

Fat Entities: Mixing pricing logic (Surge, Discounts) with the Trip entity, violating the Single Responsibility Principle.

The Right Approach

Core…