This assignment is to be undertaken individually - no group work is permitted. Background information This assignment is an exercise in simple object-oriented programming and, accordingly, you should adhere to basic object-oriented programming guidelines when designing and writing your classes, such as:
a) Setting the visibility of all instance variables to private.
b) Setting the visibility of all methods in your classes to public
c) Encapsulating both the data for a class and the methods that work with and/or manipulate that data, within the same class.
The scenario we are modelling is simulation of a computerised Auction tracking system operated by an auction house that helps customers sell their items in live auctions. Customers can both buy and sell items in the system and sellers can choose to have either an "open" auction, where the highest bid that that equals or exceeds the starting price will win the auction when it comes to an end), or a "reserve" auction, where there is a hidden reserve price that must be reached before the item if effectively "on the market" (ie. once a bid had been placed which exceeds the hidden reserve price the highest bid from that point on will win the auction when it comes to an end). Auctions will also be "opened" and "closed" manually in the system by administrators of the system when the actual auction is commenced and ended respectively. In this assignment we are focusing on the tracking of item auction information in the system - the auction company also maintains details about customers who participate in their auctions (both buyers and sellers), these requirements will be discussed in assignment 5. The auction company offers two types of auction to it's customers as follows:
- Open auctions in which the item is effectively "on the market" when the auction begins, which means the highest valid bid (which exceeds the starting price) will win the item when the auction is ends.
- Reserve auctions in which there is a "hidden" reserve price which needs to be met before the item is "on the market" - bids will still be accepted below the reserve price (as long as they equal or exceed the starting price), but the item will only be sold if the highest bid has equalled or exceeded the reserve price that has been set when the auction comes to an end..
- The details required for the handling of reserve auction information will be discussed later on in assignment 4.
You are required to design and implement an object-oriented program that models some basic functionality required in such an auction system. RMIT School of CS&IT Written by Craig Hamilton 2
Part A: AuctionItem class implementation (25 marks) An auction item requires the following details to be maintained in the system: item ID, item description, seller ID, starting price and the auction status (open or closed). Once the auction has been opened the system will also need to maintain the details of the highest bidder and the amount they have bid on the item. You should start by designing and implementing a basic AuctionItem class, as follows:
1. Define instance variables for the item ID (an int), item description (a String), seller ID (a String), starting price (a double), auction status (a String which can be "Pending", "Open" or "Closed") the current highest bid (a double) and the ID of the current highest bidder (a String).
2. Define a constructor for the AuctionItem class which accepts the item ID, item description, seller ID and starting price as parameters and stores the information in the corresponding instance variables.
This constructor should also set the auction status to "Pending" and the highest bid to zero (0). NOTE: You should not have parameters for auction status, highest bid (which are both initialised as discussed in the point above) or the bidder ID (which will be updated when a valid bid is placed on the item).
3. Define appropriate accessors for the each of the instance variables in this class.
4. Define a method public boolean hasBids(), which returns true if a valid bid has been placed on the item and false if no bid has been made (hint: a valid bid has been made if the current highest bid is equal to or greater than the starting price).
5. Define a method public double open(), which functions as described below:
If the current auction status is "Closed" "Pending" then it changes the status to "Open", calculates the listing fee for the item based on the starting price and returns the result. The price structure for listing fees is as follows: Starting Price Listing Fee
$0.01 - $5.00 $0.25
$5.01 - $20.00 $0.50
$20.01 - $ 100.00 $1.00
$100.01 - $250.00 $2.50
> $250.00 $5.00