This is just a simple auction engine implemented in Java there are a coupe things I would address with my design.
1.) if the user's bid history was decided to be too cumbersome then perhaps I could either a.) update their history once during an auction or b.) maybe sort their update history so i could immediately check if that value is already there. (maybe hash table?)
2.)There would have to be a check to see whether a user is logged in to place bids and view certain info about their bid historoy (price etc)
Thanks for taking the time to reveiw this!