Java Online Market Application Development

I need a small Java application for an online market.

Key requirements include:
- Product Listings
- Shopping Cart
- Farmer Class (inherits User)
- User Abstract Class
- Customer Class (inherits User)
- IProduct Interface
- Product Search Engine
- I/O Error Handling
- Threading and Concurrency

Ideal skills and experience:
- Strong Java proficiency
- Experience with OOP concepts
- Familiarity with threading and concurrency in Java
- Knowledge of error handling in I/O operations
- Background in developing e-commerce or market-based applications