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Final Project - Musify App

Introduction

For this project, we will create a Musify App similar to YouTube or Spotify. In your real life, you may use some kind of database. But we will handle and save data using files.

There are three different media types that you will handle -

You can create one or more playlists of these types. A playlist only contains one type of Media i.e. there can be different playlists like playlist1, playlist2, playlists.txt or any other name, etc. But playlist1 can only have songs, playlist2 can only have podcasts and so on.

A song has a Genre that can take one of these values - POP, ROCK, JAZZ. A podcast has a category that can take one of these values HEALTH, EDUCATION, TECHNOLOGY.

• Read the data from the files at the beginning of the program.
• Write the data in the files while exiting the program. 

Preamble: "The Specifications"

The slides from this lesson module for the assignment act as "the specifications" for the system we are about to build.

"The specifications" in real-life software development is the document that details the features that should be implemented in any particular project. They are the features and requirements that you, the Software Developer, and the client have agreed should be implemented in the system.

As such, you should read these specifications carefully and ensure that your program implements the requirements of the specification correctly.

Tests will be run on your program to check that you have implemented these specifications correctly. Note that for the Final Project, we will provide 20 visible tests that you can run to check that the basic functionality of your system is correct.

There will be no hidden test cases. However, we will manually upload some different data files to rerun your program and assess the correctness of your code. Your final marks for the test cases will be assessed based on how many tests passed with the different data files that we upload. The use cases that are tested using these test cases will remain same. The data format will remain same but the data itself will change. DO NOT HARD CODE ANY DATA IN YOUR PROGRAM.

So once your program passes the basic tests, we strongly recommend that you perform further tests yourself, to ensure that the required features have been implemented correctly.

How to read the specifications?

• Some inputs to the program can be invalid and should be handled accordingly by the program. These unexpected but valid scenarios will be tested and are shown below -

• Just like the previous assignment, please read carefully through the out-of-scope specifications as well. This may be embedded as a red strip in the specifications sometimes.
• Out of Scope Scenario: This scenario ........ is out of scope for this assignmentOther than this, we will use the general informational, warning, error, and assumption callouts using blue, yellow, red, and green coloured callouts.
• Also, note that the code snippets have some characters in bold that represent the inputs to the program.

Students can assume that test cases only contain outputs that are explicitly part of specifications. The test cases do not produce any output that is not mentioned in the specifications explicitly. Please note that the specifications will give you warnings and important notes where we expect special input handling. You should observe those and implement them accordingly as they will be tested while marking your program.

Preamble: Intended Learning Outcomes

The Intended Learning Outcomes for the final Project are mentioned below -

Similar to previous assignments -

A warning to those who have previous programming experience in other programming languages (like C or Python) that follow a procedural programming paradigm: Be careful to develop your program using object oriented principles, as programming and structuring your code in a way that is not object-oriented is an easy way to lose marks for structure in the assignments.

Preamble: Structure and Style

We will also be assessing your code for good structure and style.

Use methods when appropriate to simplify your code, and avoid duplicate code.

Use correct Java naming conventions for class names, variable names, and method names and put them in a well-organised way in your code i.e. it should be readable as well. Look at the conventions provided by Oracle here.

Code structure in a file is very important and improves readability. Look at the code organisation conventions provided by Oracle here.

Make sure the names you choose are meaningful, to improve the readability of your code.

Ensure to add meaningful comments in between your code and Javadoc comments for classes and methods.

We will provide a marking scheme to help guide you in the development of your program.

Academic Honesty 

DO NOT SHARE YOUR CODE WITH ANYONE WITHIN OR OUTSIDE OF THE UNIVERSITY. DO NOT COPY FROM GPT or COPILOT. Severe actions will be taken.

File Handling & Command Line Args

Command Line Arguments

Your program will either have two command line inputs or none. These are -

• User name (this will only be a first name)
• Input file name for the list of playlists.

$java MusifyApp John playlistall.txt

If there are no command line arguments present then you will -set the user name as "Stranger"

File Handling

Folder Structure

• data - There will be a data folder next to your code files and packages. This is the root folder that contains all the files and subfolders. 
• playlist - within the data folder, there will be a playlist folder. This folder contains files that define individual playlists for different kinds of media. 
• mediatext - within the data folder, there will be another folder named mediatext. This folder contains files for captions/subtitles for different media.

Files Description

1. PlaylistList - This file contains data for all the playlists that the user has created. There will only be one file that has a list of all playlists. The name of the file can vary. This file will be present in the "data" folder.
2. Playlist- This file contains all the songs, podcasts or short clips that the user has added to onesingle playlist. There will be many playlist files.
3. Captions - This file contains subtitles or captions for different kinds of media. There will be many captions files.

PlaylistList File

HEALTHFREAK,PODCAST,pod_health

Each line has data in the order -

Playlist File

Playlist of Songs

• name - name of the song
• description - some description of the song
• Artist Name - # separated Artist Name. If a song has one artist, then one name is present
• (without any # in the text). If a song has more than one artist then the artist names are
• separated by #. For example - Ed Shereen#Taylor Swift
• Genre - genre of the song (either POP, ROCK, JAZZ)
• duration in mins - duration of the song in mins. This is expected to be an integer.
• caption filename - filename where the song lyrics (captions) can be found.

Total Data Points: 6 fixed data points.

Captions File

Note that the files do not have a header describing the column names so you don't have to do special handling of the header vs the data.

When you quit the program, your program should write back any changes done to PlaylistList, and playlists back to the file/folder paths mentioned. Please do not override the captions files.

IMPORTANT NOTE: Sometimes file handling is buffered internally by the operating system as well. This means if you PrintWriter.print , you may end up with an empty file. This can be an intermittent issue. To avoid this, please use .flush() methods.

Order of reading the files

2. Once you have iterated through all the rows of the PlaylistList file mentioned in the command line args, then you should start processing individual playlist files. For example, if the PlayListlist file contains these two data rows

this means that there should be at least two files in the "data/playlist/" folder. You should append the folder name to file names like 90_rock or pod_health and try reading it in the code.

3. While iterating through the playlist file, say 90_rock, you will read each individual line, and then also process the captions file associated with it. For example, if 90_rock file has the content -

You should process the line containing song Iris and then the caption file iris_song before moving to the next line.

Note: Remember in java the file extensions doesn't matter as long as the content is text in nature. So you may or may not have any file extensions like .txt

Writing the files back

You must write the playlistList file back using the filename provided to you in the command line argument. If no command line argument is passed, then you must create the file using the name "playlists.txt".

Similarly, you must write the playlist files as per the name provided by the user or the file names that were already present in the directory "data/playlist/" when you modify these playlists. In case the user created new playlist, you must create a new file. If a media is added to the playlist then the playlist files under "data/playlist" folder should be updated with the contents.

NOTE: Windows vs Linux FileSystems handle folder path differently, You must comply to what EdStem follows i.e. Linux style paths.

Exception Handling with Files

Worst Case Scenario: Your program may behave incorrectly if not handled explicitly. These kind of inputs will be tested.

Invalid or missing file.

2. InvalidLineException - Every file expects a minimum number of fixed data points. When these data points are missing, you should raise an InvalidLineException, skip reading the line, print an error message and move on to the next line. One of the following exception messages should be printed.

3. InvalidFormatException - Some data points are expected to be in a particular format. For example, duration in minutes or episode number can only be an integer. Also, the Genre for the song or Category for the podcast are fixed. But you may have some invalid data in the files. In such cases, you must raise an InvalidFormatException and skip reading the line, print an error message and move on to the next line. One of the following exception messages should be printed.

Duration in mins not in correct format. Skipping this line. // This is printed when duration in mins is not a positiv

Incorrect Genre for Song. Skipping this line. // This is printed when genre is anything else than POP, ROCK, JAZZ.

Episode number not in correct format. Skipping this line. // This is printed when episode number for podcast is not a

Incorrect Category for Podcast. Skipping this line. // This is printed when category is anything else than HEALTH, ED

4. PlaylistFullException - A playlist can only have 5 media (song/podcast/short clip). If you try to add more than 5 songs, then you will raise a PlaylistFullException. You will print a customised message with the playlist name and mediaType

Example: Playlist 90's Rock is full. You cannot add new song to this playlist.

5. MediaNotFoundException: While processing the playlist files, you must look up the captions file. If the caption file is not found, then throw a FileNotFoundException or IOException, print a message and continue processing further data. Similarly, when you are adding new media to the playlist, the program will prompt you to add a captions file name. If the file is not found then throw a FileNotFoundException with the below message.

Cannot show captions for short clip. Media not found.

Cannot show lyrics. Media not found.

Main Menu
Program Display Message

If the program has both command line arguments, then it should show the appropriate Data Load messages and welcome messages.

In case the program finds some errors and skips some lines while loading data, it should print those error messages as well.

Once the program has loaded the data files, and shown the welcome message, it should print the main menu.

7. Exit Musify.

Option 2: View all Playlist

Use the formatter string PLAYLIST_HEADER_FORMATTER and PLAYLIST_FORMATTER provided to you in the constants file to create the formatted table.

Option 1: Create a new playlist

Case 1: User creates empty playlist.

Option 3: View the contents of a playlist

If the playlist has some content then that will be displayed, else If there is no content then an error message No <mediatype> in the playlist to view. should be shown. The mediatype could be song , podcast , shortclip

Please select one of the options.

Option 4: Removing a playlist

Option 6: Play the contents of a playlist

Option 7: Exit

Option 5: Modifying a playlist

No Playlist found