Homework 7: Music Library

Due December 2 @ 8:00pm on Autolab

1. Introduction

In this assignment, you’ll be writing the code for a music manager. We don’t specify which data structures you should use to store the information about your songs, but we do specify efficiency requirements for various pieces of functionality. These efficiency requirements should guide your choices of data structures.

You are given a plain text file of songs (there are multiple examples in the pre-prepared Eclipse project, such as tunes.txt). Each song entry in the file is formatted in the following manner:

Download a pre-prepared Eclipse Project hw7.zip and import it into Eclipse using these instructions. You will make all of your changes inside of the Java files in this project.

2. Your Tasks

You have three main tasks.

  1. Finish the Song class.
  2. Finish the MusicLibrary implementation with all of the requested methods.
  3. Write a MusicLibraryManager that provides a text based interface for managing a music library.

2.1. Finishing the Song class

You need to write a class to contain the information about an individual song.

A song object stores information about an individual song. A song will have, at least: An artist, title, album, and genre. Two songs are considered to be the same song if exactly those four things are the same. You will also need some way to keep track of which playlists a song is on.

You can decide on your own design for this class, but it must at least have the specified constructor and a correct toString(). You will also certainly need to add more methods to it. You will likely need to override both equals and hashCode, depending on how you store your data.

The toString() for this class should produce results such as…

Song [artist=Johnny Cash, title=If I Told You Who It Was, album=Out Among The Stars, genre=outlaw country, playlists=[]]
Song [artist=Johnny Cash, title=If I Were a Carpenter, album=Hello, I'm Johnny Cash, genre=outlaw country, playlists=[]]
Song [artist=Johnny Cash, title=I Won't Back Down, album=American III: Solitary Man, genre=arkansas country, playlists=[Driving Music]]
Song [artist=Diana Haddad, title=Ela Hona, album=Ela Hona, genre=lebanese pop, playlists=[Arabic Tunes, Driving Music, Khaliji Sad Melodies]]

Note that the playlists are in sorted order. That is intentional and required.

2.2. Finish MusicLibrary

The MusicLibrary class is the core of this homework. It contains a variety of methods that you need to write that are all involved in managing songs. Many of the methods have specific efficiency requirements that your implementation must meet.

Before you jump into writing code for this class, you should carefully plan what data structures you will use to store which data, ensuring you know how you will meet the efficiency requirements. If you don’t plan this properly, then you may end up needing to rewrite large parts of the homework in order to meet the efficiency requirements.

Check the documentation inside of MusicLibrary.java for details regarding the methods you need to write the efficiency requirements they have. Pay careful attention to how the efficiency requirements are specified. If, for example, an efficiency requirements says: “This must be O(M), where M is the number of artists,” then your efficiency must depend only on the total number of different artists; it cannot depend on the number of songs.

2.3. Write a MusicLibraryManager

The MusicLibraryManager class is a text-based interface that allows a user to manage a music library. Currently, the menu lists all of the functionality that the MusicLibraryManager is required to provide. You need to actually provide the functionality. Check MusicLibraryManager.java for details.

3. Grading and Submission

There are multiple parts of the grading of this assignment:

  1. For the first 75 points, your submission will be auto-graded on Autolab based on your implementation of the MusicLibrary
  2. For the next 15 points, your submission will be manually graded by running and testing MusicLibraryManager
  3. For the next 5 points, your submission will be manually graded to check for good implementation methodologies. (Did you use a good approach to solving the problems?)
  4. For the next 5 points, your submission will be manually graded to check for good testcases that you include in the main method. (Do you have 2-3 basic testcases for each method, and do they all execute automatically?)
  5. Your code will also be checked for style. The parts of style that can be checked automatically (things like spacing, indentation, the use of CamelCase, etc.) are automatically checked by the autograder. Other parts of style, such as choosing good variable names, will be checked manually. Autograded style guide violations can result in, at most, -10 points. Manually checked style guide violations can result in, at most, -5 points.

You will submit your program to Autolab. Login to the system and you will see the homework.

For this homework you’ll need to submit a zip file containing your code. Lucky for you, however, Eclipse can create this zip file for you. Check out these instructions. On Autolab, you’ll submit that exported zip file. On the page that follows your submission you will see your live score (out of 90). It may take up to a few minutes for your score to appear, during that time just hit refresh in your browser. If you receive a lower score than you expect, you can click on the score to see the feedback from the autograder.

For this assignment you have 15 submissions. Use them wisely.

3.1. Testcases

In this homework we are not providing any testcases.

For MusicLibrary you need to provide at least two testcases for each of the new methods. At least one of those must be non-basic. All of your testcases should be in the MusicLibraryTester class included with the skeleton code.

You do not need to write testcases for MusicLibraryManager.

When grading, in addition to counting testcases we will also look at the quality of what you are testing.

4. Hints

5. Important Notes