I have learned the basic of threading through various resources and now I want to implement a basic supermarket application. The features which I am looking in that application are :-

1. Billing counters where customer will do there checkout.
2. Number of items in each customer's in trolley must be different.
3. To trace weather more checkout are required or not.
4. Calculate billing time, wait time etc.

I am not sure how to start this using thread. If any one can suggest the steps how to proceed with development that will be very helpful. I am planning to use java AWT from UI prospective.