Can someone explain this in java?

Ebay Auction Data : http://www.cs.washington.edu/research/xmldatasets/data/auctions/ebay.xml

Yahoo Auction Data : http://www.cs.washington.edu/research/xmldatasets/data/auctions/yahoo.xml

bigdata.jar: http://cs.berry.edu/big-data/bigdata.jar

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HOMEWORK 6- Fall 2020 HOMEWORK 6 - due Tuesday, November 17th no later than 5:00PM REMINDERS: - Be sure your code follows the mm for CSE214. . Make sure you read the warnings about Wm. Remember, all work you submit for homework or exams MUST be your own work. . Login to yourgw and click "Submit Assignment" to upload and submit your assignment. You may use (and are encouraged to use) any Java API Data Structures you like to implement this assignment. You may use Scanner, InputStreamReader, or any other class that you wish for keyboard input. When working with data, we must choose the best data structure to manipulate the data set in order to achieve efficient results. A very basic array can store information without a problem, but is inefficient when we are constantly storing and searching for data. The idea of a table is created to increase the efficiency and avoid such problems. Tables store data using a tuple . We choose a special field of an object, and use it to uniquely identify the entire object. Therefore, when we store and search for an object, we will use the key to save or search for the object. Ideally, this will reduce the algorithm to 0(1). For this assignment, you are allowed to use a HashTabIe, or a HashMap. For this assignment, we are working with a real auction data online. The data will be in the form of an XML file. There may be extraneous data that we do not need in our analysis. We will selectively limit our object construction with information that we are interested in. To get started, visit the following websites: E A i n D Yahm Auction Data Since these URLs are long, we provide shortcuts via the correspnding TinyURLs: http://tinyurl.combf592h - Ebay Auction Data http://tinyurl.com/p7vub89 - Yahoo Auction Data Manually extracting the data will be a tedious and error prone job. You will learn how to use a data extraction tool to analyze an XML file. You can download the file here: W. In addition to the sample code provided below, there is documentation available herezBig Data Documentation USING A JAR IN ELCIPSE: Right click the project name in the \"Package Explorer\" tab (on the left, by default): Select \"Build Path"a Select \"Add External Archives..."a navigate to where you saved biqdatagta; and select it. name A JAR IN NEI'BEANS: Right click the project name in the \"Package Explorer\" tab (on the left, by default Click on \"Properties" a Select \"Libraries\" on the lefa Click on "Add JAR/Folder" on the rig hta navigate to where you saved bigdata.'ar and select it. Now you can \"import big .dataDataSource" in your source code (or any other class from the bigdata library that you need). Note: DO NOT SUBMIT bigdatajar along with your Java source files, otherwise 10 points will be deducted. If we have the URL of the XML file, we can connect to it using the library functions. First, we must connect() to the URL, then loadO the data. Finally, we can fetchO the information. Sample Code: The file contains the following content: 1 dtem> 2 import big.data.*; DataSource d3 = DataSource.connect("sample_file.xml").load(); String str = ds.fetchString("item/attr"); // normally, we can extract a single string data in the path item/attr, but we have multiple values in our case. Instead, we should do the following: String myList = ds.fetchStringArray("item/attr"); You will mostly use fetchStringArrayO in this assignment. Sometimes, the information on the XML may not be complete. You might find that your fetch will return an empty string (i.e. ""). In that case, you can replace it with the string: "N/A". Required Classes The following sections describe classes which are required for this assignment. Each section provides a description and the specifications necessary to complete each class. If you feel that additional methods would be useful, feel free to add them during your Implementation as you see fit. However, all the variables and methods in the following specifications must be included in your project. NOTE: All classes listed should implement theSerializable interface. 1. Auction Write a fully-documented class named Auction which represents an active auction currently in the database. TheAuction class should contain member variables for the seller's name, the current bid, the time remaining (in hours), current bidder's name, information about the item, and the unique ID for the auction. In addition, the class should implement a toString() method, which should print all of the data members in a neat tabular form. The Auction class can only be altered by a single member method callednewBid(), which takes in the name of a bidder and their bid value. This method checks to see if the bid value is greater than the current bid, and if it is, replaces the current bid and buyer name. There should be getter methods for each member variable, however, no setters should be included. The following is a list of information you should be paying attention to: listing/seller_info/seller_name listing/auction_info/current_bid listing/auction_info/time_left listing/auction_info/id_num listing/auction_info/high_bidder/bidder_name / the following should be combined to get the information of the item listing/item_info/memory listing/item_info/hard_drive listing/item_info/cpu public Auction() - constructor (you may include a constructor with parameters) . An int member variable: . time Remaining . A double member variable: . currentBic Four String member variables: . auctionl sellerName . buyerName iteminfo . public void decrementTimeRemaining(int time) . Brief: . Decreases the time remaining for this auction by the specified amount. If time is greater than the current remaining time for the auction, then the time remaining is set to 0 (i.e. no negative times). . Postconditions: . timeRemaining has been decremented by the indicated amount and is greater than or equal to 0. . public void newBid(String bidderName, double bidAmt) throws ClosedAuctionException . Brief: Makes a new bid on this auction. If bidAmt is larger than currentBid, then the value of currentBid is replaced by bidAmt and buyerName is is replaced by bidderName . Preconditions: . The auction is not closed (i.e. timeRemaining > 0). . Postconditions: currentBid Reflects the largest bid placed on this object. If the auction is closed, throw aClosedAuctionException. Throws: . ClosedAuction Exception: Thrown if the auction is closed and no more bids can be placed (i.e. timeRemaining == 0). public String toString() - returns string of data members in tabular form. . Getters for all data members (no setters). 2. Auction Table The database of open auctions will be stored in a hash table to provide constant time insertion and deletion. Use the auctionID as the key for the corresponding Auction object. In this assignment, you may provide your own implementation for the AuctionTable class, or you may use a hash table implementation provided by the Java API. If you would like to know more about the Java API implementations, you should read the Orcale documentation forjava.util.Hashtable and java.util.HashMap. In addition to the standard hash table functionality, your class should include a function which will build anAuctionTable from a URL using the BigData library. This function should connect to the data source located at the URL, read in all the data members for each record stored in the data source, construct new Auction objects based on the data, and insert the objects in to the table. Exceptions should be thrown if the data source could not be connected to or contains invalid syntax structure. public static AuctionTable buildFromURL(String URL) throws IllegalArgumentException . Brief: . Uses the BigData library to construct an Auction Table from a remote data source. . Parameters: . URL - String representing the URL fo the remote data source. . Preconditions: . URL represents a data source which can be connected to using the BigData library. The data source has proper syntax. . Postconditions: None. . Returns: . The Auction Table constructed from the remote data source. . Throws: . IllegalArgumentException: Thrown if the URL does not represent a valid datasource (can't connect or invalid syntax). public void putAuction(String auctionID, Auction auction) throws IllegalArgumentException . Brief: - Manually posts an auction, and add it into the table. . Parameters:- auctionlD - the unique key for this object - auction - The auction to insert into the table with the corresponding auctionlD e Preconditions: - None. o Postconditions: . The item will be added to the table it all given parameters are correct. 0 Throws: - IllegalArgumentException: It the given auctionlD is already stored in the table. . public Auction getAuction(String auctionlD) c Brief: . Get the information of an Auction that contains the given ID as key a Parameters: - auctionlD - the unique key for this object a Returns: - An Auctlon object wlth the given key, null otherwise. o public void letTimePass(int numHours) throws lllegalArgumentException 0 Brief: - Simulates the passing of time. Decrease the timeRemaining of all Auction objects by the amount specified. The value cannot go below 0. o Parameters: - numHours - the number of hours to decrease the timeRemaining value by. c Postconditions: - All Auctions in the table have their timeRemaining timer decreased. If the original value is less than the decreased value, set the value to 0. o Throws: - I|legalArgumentException: It the given numHours is non positive . public void removeExpiredAuctionsO a Brief: - Iterates over all Auction obiects in the table and removes them if they are expired (timeRemaining == 0). o Postconditions: - Only open Auction remain in the table. . public void printTableO 0 Brief: . Prints the AuctionTable in tabular form. 3. AuctionSystem Write a fully-documented class named AuctionSystem. This class will allow the user to interact with the database by listing open auctions, make bids on open auctions, and create new auctions for different items. In addition, the class should provide the functionality to load a saved (serialized) AuctionTable or create a new one if a saved table does not exist. On startup, the AuctlonSystem should check to see If the flleauctlons.ob] exlsts In the current directory. If It does, then the file should be loaded and deserialized into an AuctionTable for new auctions/bids (See the section below for information on theSeria/izable interface). It the file does not exist, an empty AuctionTable object should be created and used instead. Next, the user should be promted to enter a username to access the system. This is the name that will be used to create new auctions and bid on the open auctions available in the table. When the user enters 'Q' to quit the program, the acution table should be serialized to the filauctionsobj. That way, the next time the program is run, the auctions will remain in the database and allow different users to make bids on items. If you would like to 'reset' the auction table, simply delete the auctionsobi tile. . An AuctionTable member variable: a auctionTable o A Strlng member variable: o username . public static void main(String args) a Brief: - The method should first prompt the user for a username. This should be stored in username The rest of the program will be executed on behalf of this user. Implement the following menu options: I (D) - Import Data from URL . (A) - Create a New Auction . (B) - Bid on an Item . (I) - Get Info on Auction . (P) - Print All Auctions . (R) - Remove Expired Auctions . (T) - Let Time Pass 0 (Q) - Quit Serializable Interface You will also work with the idea of persistence. This means that our program should save all data from session to session. When we terminate a program, normally the data will be lost. We will preserve this data by using Serializable Java API and binary object files. All your classes should simply implement the java.io.Serializanion interface. Example: Your AuctionTable class contains information for all auctions saved in the electronic database. You would want to preserve this data, so you can load this data the next time you run your program. You would do the following: 1. Modify the AuctionTable so that it implements the Serializable interface. Also, the Auction class should also make this implementation. No other changes are necessary. public class Auction Table implements Serializable // Member methods as is 2. In your application that contains the hash, you can include code that will save the hash into a file so it can be read in again later. To do this, you need to create an ObjectOutputStream to send the data to, and then use the writeObject method to send the hash to the stream, which is stored in the specified file. FileOutputStream file = new FileOutputStream("auction.obj"); ObjectOutputStream outStream = new ObjectOutputStream(file); Auction Table auctions = new Auction Table(/*Constructor Parameters*/); // missing code here sets up the hash in some way / the following line will save the object in the file outStream.writeObject(auctions); . When the same application (or another application) runs again, you can initialize the member using the serialized data saved from step 2 so you don't have to recreate the object from scratch. To do this, you need to create an ObjectinputStream to read the data from, and then use the readObject method to read the hash from the stream. FileInputStream file = new FileInputStream("auction.obj"); ObjectinputStream inStream = new ObjectinputStream(file); Auction Table auctions; auctions = (AuctionLibrary) inStream.readObject(); / missing code here can use the same hash from step 2 now Sample Input/Output: // Comment in green, input in red, output in black Starting... No previous auction table detected. Creating new table... // Notify if loading or not. Please select a username: student@stonybrook.edu Menu: (D) - Import Data from URL (A) - Create a New Auction (B) - Bid on an Item () - Get Info on Auction P) - Print All Auctions (R) - Remove Expired Auctions T) - Let Time Pass (Q) - Quit Please select an option: D Please enter a URL: http://tinyurl.combf5g2h // TinyURL for http://www.cs.washington.edu/research/xmldatasets/data/auctions/ebay.xml Loading... Auction data loaded successfully! // Menu not printed in sample i/o. Please select an option: P Auction ID | Bid Seller Buyer Time | Item Info // truncated to fit on one line 511601118 | $ 620.00 | cubsfantony gosha555@excite.com |110 hours | Pentium III 933 System - 256MB PC133 SDram 511448507 | $ 620.00 | ct-inc petitjc@yahoo.com | 54 hours | Pentium III 800EB-MHz Coppermine CPU - 256 511443245 | $ 1,025.00 | ct-inc hsclm9@peganet.com | 54 hours | Intel Pentium III 933EB-MHz Coppermine CPU 511364992 | $ 610.00 | bestbuys4systems | wizbang4 53 hours | Genuine Intel Pentium III 1000MHz Processo 511357667 | $ 535.00 | sales@ctgcom.com | chul2@mail.utexas.edu | 53 hours | INTEL Pentium III 800MHz - 256MB sdram -40 Please select an option: B Please enter an Auction ID: 511364992 Auction 511364992 is OPEN Current Bid: $ 610.00 What would you like to bid?: 625.00 Bid accepted. // Menu not printed in sample i/o. Please select an option: P Auction ID| Bid Seller Buyer Time | Item Info // truncated to fit on one line 511601118 | $ 620.00 | cubsfantony | gosha555@excite.com | 110 hours | Pentium III 933 System - 256MB PC133 SDram 511448507 | $ 620.00 | ct-inc petitjc@yahoo.com 1 54 hours | Pentium III 800EB-MHz Coppermine CPU - 256 511443245 | $ 1,025.00 | ct-inc 511364992 | $ 625.00 | bestbuys4systems hsclm9@peganet.com | 54 hours | Intel Pentium III 933EB-MHz Coppermine CPU | student@stonybrook.edu | 55 hours | Genuine Intel Pentium III 1000MHz Processo 511357667 | $ 535.00 | sales@ctgcom.com chul2@mail.utexas.edu | 55 hours | INTEL Pentium III 800MHz - 256MB sdram -4// Menu not printed in sample i/o. Please select an option: A Creating new Auction as student@stonybrook.edu. Please enter an Auction ID: 100000000 Please enter an Auction time (hours): 24 Please enter some Item Info: Core i5 2.7GHz - 4GB DDR3 - 750GB HDD Auction 100000000 inserted into table. // Menu not printed in sample i/o. Please select an option: P Auction ID | Bid Seller Buyer Time | Item Info // truncated to fit on one line 511601118 | $ 620.00 | cubsfantony 511448507 | $ 620.00 | ct-inc gosha555@excite.com | 110 hours | Pentium III 933 System - 256MB PC133 SDram petitjc@yahoo.com | 54 hours | Pentium III 800EB-MHz Coppermine CPU - 256 511443245 | $ 1,025.00 | ct-inc 511364992 | $ 625.00 | bestbuys4systems hscim9@peganet.com | 54 hours | Intel Pentium III 933EB-MHz Coppermine CPU | student@stonybrook.edu | 55 hours | Genuine Intel Pentium III 1000MHz Processo 511357667 | $ 535.00 | sales@ctgcom.com 100000000 chul2@mail.utexas.edu | 55 hours | INTEL Pentium III 800MHz - 256MB sdram -40 student@stonybrook.edu| | 24 hours | Core 15 2.7GHz - 4GB DDR3 - 750GB HDD // Note that Bid and Buyer are missing for the new record. These correspond to 'null' attributes in the database. / Menu not printed in sample i/o ct an option: G Writing Auction Table to file... // Serialize the Auction Table. Done! Goodbye. // Starting up again Starting... Loading previous Auction Table... // Loading from file. Please select a username: buyer@gmail.com // Menu not printed in sample i/o. Please select an option: B Please enter an Auction ID: 100000000 Auction 100000000 is OPEN Current Bid: None What would you like to bid?: 1500.00 Bid accepted // Menu not printed in sample i/o. Please select an option: P Auction ID | Bid Seller Buyer | Time | Item Info // truncated to fit on one line 511601118 | $ 620.00 | cubsfantony | gosha555@excite.com | 110 hours | Pentium III 933 System - 256MB PC133 SDram 511448507 | $ 620.00 | ct-inc 511443245 | $ 1,025.00 | ct-inc petitjc@yahoo.com | 54 hours | Pentium III 800EB-MHz Coppermine CPU - 256 | hsclm9@peganet.com | 54 hours | Intel Pentium III 933EB-MHz Coppermine CPL 511364992 | $ 625.00 | bestbuys4systems 511357667 | $ 535.00 | sales@ctgcom.com | student@stonybrook.edu | 55 hours | Genuine Intel Pentium III 1000MHz Processo | chul2@mail.utexas.edu | 55 hours | INTEL Pentium III 800MHz - 256MB sdram -40 100000000 | $ 1,500.00 | student@stonybrook.edu| buyer@gmail.com | 24 hours | Core i5 2.7GHz - 4GB DDR3 - 750GB HDD // Menu not printed in sample i/o. Please select an option: 1 How many hours should pass: 30 Time passing... Auction times updated // Menu not printed in sample i/o. Please select an option: P Auction ID Bid Seller Buyer Time | Item Info // truncated to fit on one line 511601118 | $ 620.00 | cubsfantony 511448507 | $ 620.00 | ct-inc | gosha555@excite.com | 80 hours | Pentium III 933 System - 256MB PC133 SDram petitjc@yahoo.com | 24 hours | Pentium III 800EB-MHz Coppermine CPU - 256 511443245 | $ 1,025.00 | ct-inc 511364992 | $ 625.00 | bestbuys4systems hscim9@peganet.com | 24 hours | Intel Pentium III 933EB-MHz Coppermine CPU | student@stonybrook.edu | 25 hours | Genuine Intel Pentium III 1000MHz Processo 511357667 | $ 535.00 | sales@ctgcom.com | chul2@mail.utexas.edu | 25 hours | INTEL Pentium III 800MHz - 256MB sdram -40 100000000 | $ 1,500.00 | student@stonybrook.edu| buyer@gmail.com | 0 hours | Core i5 2.7GHz - 4GB DDR3 - 750GB HDD // Menu not printed in sample i/o. Please select an option: B Please enter an Auction ID: 100000000 Auction 100000000 is CLOSED Current Bid: $ 1,500.00You can no longer bid // Menu not printed in sample i/o. Please select an option: I Please enter an Auction ID: 511448507 Auction 51148507 Seller: ct-inc Buyer: petitjc@yahoo.com Time: 24 hours Info: Pentium III 800EB-MHz Coppermine CPU - 256MB PC133 SDRAM - 30.7GB IBM Deskstar ATA100 7200RPM // Menu not printed in sample i/o. Please select an option: R Removing expired auctions... All expired auctions removed // Menu not printed in sample i/o. Please select an option: P Auction ID | Bid Seller Buyer Time | Item Info // truncated to fit on one line 511601118 | $ 620.00 | cubsfantony 511448507 | $ 620.00 | ct-in | gosha555@excite.com | 80 hours | Pentium III 933 System - 256MB PC133 SDram petitjc@yahoo.com | 24 hours | Pentium III 800EB-MHz Coppermine CPU - 256 511443245 | $ 1,025.00 | ct-in hsclm9@peganet.com | 24 hours | Intel Pentium III 933EB-MHz Coppermine CPU 511364992 | $ 625.00 | bestbuys4systems | student@stonybrook.edu | 25 hours | Genuine Intel Pentium III 1000MHz Processo 511357667 | $ 535.00 535.00 | sales@ctgcom.com | chul2@mail.utexas.edu | 25 hours | INTEL Pentium III 800MHz - 256MB sdram -4 // Menu not printed in sample i/o. Please select an option: Q Writing Auction Table to file... // Serialize the Auction Table. Done! Goodbye. Course Info | Schedule | Sections | Announcements | Homework | Exams | Help/FAQ | Grades | HOME