CS 230 Spring 2007                          Assignment 10 – More Files–                                                          100 points

Assigned: 04/04/2007

Due: 04/18/2007 at the start of class

Pre-Lab (Do Before Lab):  Bring materials – a way to save a copy for you and a copy to turn in. Plan out tasks, objects, and events needed for program. Write pseudocode for the main buttons and for functions / independent sub procedures.

.

Main Assignment:

LaSoogle Labs is developing an online radio station in which you create your own personal radio station and music is streamed to you based on what you like and don’t like (like other services already out there).  Your program is a simplification dealing with ranking songs (only). .

· The program should get from a file (songs.txt) a list of songs and display them in a list box.

· When the user selects a song from the song list box, the song information should be displayed in two read-only text boxes or in labels.  Separate the song title and artist (the file format is to divide these using the word “by” instead of a comma.)

· When a user specifies a rating (0-5) AND selects a “Rate” button, write the rating (song, artist and rating) to a comma-delimited text file for later tabulation (add it to those already in the file), and remove the song from the list box of songs. (DO NOT have the rating recorded immediately upon selection in case of inadvertent click).

· Provide the rate capability, a clear (clear song and artist, set rating to default, and clear any selection in the list box (see below)),  and an exit capability.

· A sample interface is provided on page 2. Don’t let that constrain your creativity. Use it to help understand what I see as the inputs and outputs.

Hand in:

• Floppy disk  or CD-R with an entire folder containing all files related to the project (or e-mail with zipped attachment containing all files related to the project).
• Please set the name of the project to something other than the default name (WindowsApplication1, …). It is helpful if you use a name that identifies you as well as the assignment (e.g. yourlastname assignment 10).
• Use Windows to copy the whole folder, instead of trying to “Save As”.
• Print out of your code.  

Task Details:

• In clearing, to clear the selection of an item in the list box you can use: listboxname.SelectedItem = Nothing.  “nothing” is a built in value – typing it in (nothing) you should see it turn blue. 
• Validation:

· It is permissible (recommended) to use a combo box to obtain the user’s rating of a song.  You can avoid the need to validate rating at all if you:

1. use a DropDownStyle property value of DropDownList – which makes it impossible for the user to type in values of their own, and

2. always ensure that the combo box has a default value. When loading the form and when clearing, set cmboboxname.SelectedIndex = thenumberoftheitemyouwanttobethedefault (starts counting with zero)

· If the rating is done as a regular text box, you must validate as always.

· You need to ensure that a song has been selected before accepting a rating (display a msgbox complaining if not)

• After the Rate button has been recorded, give the listener some kind of confirmation (e.g. a msgbox) and automatically clear the song and artist choices and set the rating back to default.
• Remove the successfully rated song from the list box using listboxname.Items.Remove(itemtoremove) where itemtoremove is the item to be removed.  If the item will still be selected, this could be listboxname.ItemSelected
• When you remove the song from the songs listbox (and when you clear the list box selection for the clear button), that will result automatically in a change to the item selected property of the list box, triggering an event. Your event procedure for that event needs to protect against that crashing your program (the selected item will be set to “nothing”. To test if a selected item is nothing you cannot test for = Nothing. You need to do a test checking:  listboxname.SelectedItem is Nothing
• You must use the filename specified above, so I can easily test a bunch of different programs in a row. Sample files are provided on the assignments page of my www site. In the spirit of thorough testing of programs, you should try other versions of files as well.
• We have covered procedures and functions – I recommend that you continue to use them (e.g. extracting a line of text from the text in a file).

• MAKE SURE YOUR PROGRAM WORKS! (i.e. gets the correct answers).  It doesn’t have to just run, it needs to always run correctly!  It should correctly handle anything the user does. Think up some different examples to test the program on. 

Miscellaneous

• You must turn on Option Explicit and Option Strict.
• Put YOUR NAME, e-mail address, date, and purpose of the program in comments at the beginning of the program. The purpose should be what the program is supposed to do, not the learning goals. Comments are indicated with a single quote (everything after the single quote is only for humans)
• You MUST include comments that explain your program in order to get full credit.
• Define numbers (especially those that appear more than once and/or could change sometime in the future) as named constants.
• Remember to use meaningful variable names
• Remember to indent to show the structure of the program (VB usually does this correctly).
• Name all textboxes, list boxes, comboboxes, and buttons meaningfully, and use conventions for starting their names.
• Make textboxes that user should never enter a value in (results / outputs) “Read Only”.
• Put your name on the form as a Label or as part of the form title.
• Try to use good user interface design. Make clear what user needs to do and what the answers mean. Make error messages as clear and helpful as possible!