Question

Use the following information to create a program that allows the user to manipulate a music playlist and view its content.

Your program should contain 3 separate classes: a Song class, a Playlist class, and a Demo class.
In this program, the Playlist class will function as a doubly linked list that contains Song objects. The Demo class will be used to make modifications to the Playlist.
Must include short comments throughout your code (each section) to describe variables, constants, classes, etc.
Song Class
This class should contain the following fields:
name: String
artist: String
album: String
length: int (This is the length of the song in seconds)
next: Song (This is a reference to the song that follows this song in the list)
previous: Song (This is a reference to the song that precedes this song in the list)
The Song class should contain the appropriate getters and setters for these attributes, a no-arg constructor, and a constructor that accepts the following arguments: name, artist, album, and length.
Playlist Class
This class will act as our doubly linked list. This class should contain the following attributes:
head: Song
A dummy node (a blank song object that will represent the first song in the playlist)
tail: Song
A dummy node (a blank song object that will represent the last song in the playlist)
size: int
The number of songs in the playlist
The Playlist class should contain a no-arg constructor which
initializes the size, head and tail attributes. This no-arg constructor should also properly connect the head and tail nodes of the doubly linked list.
The Playlist class should also contain the following methods:
- A method that accepts a Song object and adds it to the end of the Playlist.
- A method that accepts 2 Song objects (a new Song to be added, and a Song that is currently playing from the playlist). This method will insert the new Song into the playlist at the position directly after the Song that is currently playing.
- A method that accepts a Song object, returns nothing, and removes the Song from the playlist.
- A toString method that prints out the contents of the Playlist. This toString method should also calculate and display the number of songs in the playlist, as well as the length of the playlist in minutes and seconds.
Demo Class
This class will serve to accept user input and manipulate the Playlist doubly linked list.
The Demo class should instantiate a Playlist object and display a menu to the user that will allow for the following actions:
1. Add a Song to the Playlist
2. Insert a new Song after the Song that is currently playing
(If a song is being added/inserted to an empty playlist, that song should then be set to be the one that is currently playing.)
3. Print the contents of the Playlist
4. Display the current Song
(When displaying the current song for the first time, the first song in the playlist should be displayed.)
(To accomplish this, create a Song reference variable and assign it the first Song in the Playlist)
5. Remove the current song
(When removing the current song, the new current song will be the song that directly follows the removed song.)
6. Skip to the next song
(If you are at the end of the Playlist, the next Song should be the first Song in the playlist.)
7. Return to the previous song
(If you are at the beginning of the Playlist, the previous Song should be the last Song in the playlist.)
8. Exit
Validate the user’s input for the menu option. The user should be required to enter a valid menu option before advancing.
If any of the options chosen would not work due to there being no applicable songs in the playlist, an appropriate error message should be displayed.
The user should be allowed to repeatedly select menu options until they choose to Exit.

Answer 1

A Java program is created to simulate a music playlist with Song, Playlist, and Demo classes, where the Playlist functions as a doubly linked list, and the Demo class allows for user interaction with the playlist.

Step-by-step explanation:

Music Playlist Program Using Classes in Java

The task is to create a Java program that simulates a music playlist using three classes: Song, Playlist, and Demo. The Song class holds the details of a song, while the Playlist manages the songs using a doubly linked list structure. The Demo class acts as the user interface for interacting with the playlist through various operations like adding songs, inserting a song after the current song, removing songs, and navigating through the playlist.

Song Class Definition

The Song class includes information such as name, artist, album, and length of the song. It also contains references to the next and previous Song objects in the playlist, acting as a node in the doubly linked list. To facilitate data access, getters and setters are provided.

Playlist Class Definition

The Playlist class manages the songs using head and tail dummy nodes and keeps track of the playlist size. It supports operations for adding songs to the end, inserting songs at a specific position, removing songs, and a toString method to view the playlist content, along with the total length in minutes and seconds.

Demo Class Definition

Finally, the Demo class is designed for user interaction, allowing the user to perform various actions on the Playlist, such as adding, inserting, and removing songs, printing the playlist, and navigating between songs. It ensures user input validation and displays error messages as needed. This setup forms a basic user interface for the playlist manipulation.