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Design an object-oriented system that models the core functionality of LinkedIn — a professional networking platform where users build profiles, grow connections, share posts, search for jobs, and message each other.
The system should support rich profiles (experience, education, skills with endorsements), a connection request workflow, a news feed of posts from connections, job posting and application, and direct messaging.
User registration and profile
Register users and build rich profiles with experience, education, and skills
Connection management
Send, accept, reject, and remove connections between users
Skill endorsements
Connections can endorse each other's skills to build credibility
Post creation and feed
Create text posts; connections see posts in their news feed sorted by recency
Like and comment
React to posts with likes and comments
Job postings
Post and search job listings; users can apply to jobs
Direct messaging
One-on-one messaging between connected users
Search
Search users by name, headline, or skills; search jobs by title or company
Before diving into code, clarify the use cases and edge cases. Understanding the problem deeply leads to better class design.
Identify the primary actions users will perform. For a parking lot: park vehicle, exit vehicle, check availability. Each becomes a method.
Who interacts with the system? Customers, admins, automated systems? Each actor type may need different interfaces.
What are the limits? Max vehicles, supported vehicle types, payment methods. Constraints drive your data structures.
What happens on overflow? Concurrent access? Payment failures? Thinking about edge cases reveals hidden complexity.
The complete explanation is included with Career and All Access. Compare it with your approach once you’ve worked through the problem.