A07

Due Date: Friday, November 3
File(s) to be submitted: MusicTrack.java
Sample Output: SampleOutput.html
Starter Files:

• TestMusicTrack.java

MusicTrack (objects with constructors, getters, and setters)

Summary

We are creating a non-program class this week. The MusicTrack class keeps track of the list of music tracks, as the name suggests!

I have provided a tester program. Do not change the tester program except by deleting the lines labeled DELETE THIS LINE when .... If you change the program code, then your MusicTrack class code probably won't work the way we want it to.

Exception: You are allowed to change the package name or delete the package a07; command completely.

The tester program tests the MusicTrack class bit by bit. You should make sure that each bit is completely correct before you move on to the next bit. Create the methods in the order TestMusicTrack uses.

Note for those with computer programming experience. We know that having the constructors and setters print error messages is not best practice. But we want you to do it anyway. We are not going to cover throwing and catching exceptions until next term (CSCI 1228), so we can't expect beginners to know how to do that. So if you do throw exceptions, our testing programs won't work, and you will get a bad grade.

Also, we want you to print the error messages to System.out instead of System.err. For similar reasons.

Details

MusicTrack objects have four instance variables, namely artist, title, length and downloadCount.

• The instance variable artist holds the name of the artist.
• The instance variable title holds the name of the music track.
• The instance variable length represents the length of the track in minutes (e.g., a 3 minutes and 30 seconds track has a length of 3.5)
• The instance variable downloadCount represents the number of times this music track has been downloaded.

This class also has the following public methods:

• MusicTrack: This is the constructor in which you need to initialize all the instance variables. Make sure the corresponding parameters for length and downloadCount are positive numbers; otherwise set them to 0 and print a warning message as shown in the sample output.
• Getters for all instance variables: getArtist, getTitle, getLength and getDownloadCount.
• Setters for all instance veriables: setArtist, setTitle, setLength, setDownloadCount. Again, make sure the corresponding parameters for length and downloadCount are positive numbers; otherwise print a warning message as shown in the sample output.

Grading Outline

• 12 points: The program has 4 instance variables defined properly from appropriate data types.
• 10 points: The constructor has been implemented properly to initialize all instance variables.
• 8 points: The constructor produces appropriate error message for invalid parameters and set the corresponding instance variables to the correct value.
• 5 points: The method getArtist works as expected.
• 5 points: The method getTitle works as expected.
• 5 points: The method getLength works as expected.
• 5 points: The method getDownloadCount works as expected.
• 5 points: The method setArtist has been implemented properly.
• 5 points: The method setTitle has been implemented properly.
• 10 points: The method setLength has been implemented properly (5 points) and functions correctly in case of invalid parameters (5 points).
• 10 points: The method setDownloadCount has been implemented properly (5 points) and functions correctly in case of invalid parameters (5 points).
• 5 points: The opening Javadoc has been provided properly.
• 10 points: All methods have proper javadocs.
• 5 points: All style rules are followed including appropriate indentation, commenting and variable names.