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460 CSc Database Design Fall 2008 (McCann) http://www.cs.arizona.edu/classes/cs460/fall08 Program #1: Text to Binary File Conversion Due Date: September 9 th , 2008, at the beginning of class Overview: In the not to distant future, you will be writing a program to create an index on a binary le. I could just give you the binary le, or merge the two assignments, but after a long summer, creating the binary le from a generically formatted text le makes for a nice shake o the rust assignment, plus it provides a gentle (?) introduction to binary le processing. A binary le is just a le that contains information in the same format in which the information is held in memory. (In a standard text le, all information is stored as ASCII or UNICODE characters.) As a result, binary les are faster and easier for a program to read and write than are text les. As long as the le doesn t need to be read by people or ported to a di erent type of system, binary les are often the best way to store program information. For this program, we have lines of data items that we need to store, and each line s items need to be stored as a group (in a database, such a group is called a record ). Making this happen in Java requires a bit of e ort; Java wasn t originally designed for this sort of task. By comparison, systems languages like C and C++ can interact more directly with the operating system and provide more convenient le I/O. On the class web page you ll nd a sample Java binary le I/O program, which should help you gure out what needs to be done. Assignment: Linked to the class web page is a le named 2008_FE_guide.csv. This is a le consisting of over 1200 lines of data on automobile fuel economy for the 2008 model year, courtesy of the U.S. Department of Energy and the U.S. Environmental Protection Agency. Using Java, write a program that: 1. 2. 3. 4. Creates a binary version of the text le Closes that binary le Re opens the same binary le (for read access) Reads and prints to the screen the content of the rst ve records of data and the last ve records of data in the binary le, along with some statistics (see the details in the Output section, below). Data: The data le name and location are given in the Assignment section, above. Your program can read the le directly out of that directory; just use the complete path name of the le when you open the le. There s no reason to waste disk space by making a copy of the le in your account. Each of the 1200+ lines in the le contain 31 elds (pieces) of information, separated by commas (thus the .csv le extension: Comma Separated Values). Here is a sample line: TWO SEATERS,ASTON MARTIN,V8 VANTAGE,4.3,8,Auto(S6),R,12,13,20,15,16.1945,27.4018,19.8474,P,G,,,,,,,,,3002, ,4MODE ,4,1,6-Aug-07,DERIVED The rst line of the le has abbreviated eld descriptions. Additional explanation of these elds is available from the le 2008_FE_guide.txt, also available from class the web page. I ve provided the URLs of the sources of this information below, and linked them to the class web page. Note that the line of descriptions is not to be stored in the binary le; we only want data stored in that le, not descriptions of the data (a.k.a. metadata). (Continued...) Output: Your program needs to create the binary le, of course. The required on screen output is the (ASCII) content of the rst ve and last ve lines of processed data, along with the total number of data records processed (don t count that rst description line of the .csv le), and the Manufacturer and Car Line of both the car with the highest COMB MPG (GUIDE) and the car with the lowest COMB MPG (GUIDE). You are welcome and encouraged to add additional output if you have extra time and ambition (e.g., time required for the processing, mean eet MPGs, etc.). The format of the output is up to you, but the output should be easy to read Hand In: You are required to submit your completed program le(s) using the turnin facility on lectura. The submission folder is cs460p1. Instructions are available from the document of turnin instructions linked to the class web page. Name your main program source le Prog1.java so that we don t have to guess which les to compile, but feel free to split up your code over additional les if you feel that doing so is appropriate. Want to Learn More? http://www.fueleconomy.gov/feg/download.shtml The page with links to the fuel economy data. http://www.fueleconomy.gov/feg/epadata/Readme.txt The incomplete and sloppily formatted descriptions of the data elds. Other Requirements and Hints: Don t hard code values in your program if you can avoid it. For example, don t assume a certain number of records in the input le or the binary le. Your program should automatically adapt to simple changes, such as more or fewer lines in a le or changes to the le names or locations. For example, we may test your program with a le of just 3 lines. We expect that your program will handle this situation gracefully. Once in a while, a student will think that create a binary le means convert all the data into the characters 0 and 1 . The binary I/O functions in Java will read/write the data in binary format automatically. Wondering how to e ciently get the last ve records from a binary le? Remember: The Java API is your friend! Comment your code according to the style guidelines as you write the code (not an hour before class!). The requirements and some examples are available from: http://www.cs.arizona.edu/~mccann/style.html You can make debugging easier by using only a line or two of data from the .csv le for your initial testing. Try running the program on the complete le only when you can process that reduced data le successfully. Finally: Start early! File processing is often tricky. Also, after the long, relaxing summer, your programming skills are probably a little stale.

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