Question

Introduction

In this final programming exercise, you'll get a chance to put together many of the techniques used during this semester while incorporating OOP techniques to develop a simple song playlist class. This playlist class allows a user to add, remove and display songs in a playlist.

The Base Class, Derived Class and Test Client

Unlike the other PAs you completed in zyLabs, for this PA you will be creating THREE Java files in IntelliJ to submit. You will need to "upload" these into zyLabsfor grading. There will be two class files and a single client file, details of which are described below.

• SongBase.java - Base class definition for a song.
• PlaylistDerived.java - Extends the base class definition to add functionality for a playlist of several songs (aka SongEntry objects).
• PlaylistClient.java - Client program that runs and tests the base/derived class hierarchy.

Building the SongBase Class:

The members of the SongBase class are listed in a diagram below known as a Unified Modeling Language (UML) diagram. You must use the same field names and method names as listed in the diagram. This will insure that the included tests for the program will work for your implemented class.

How to read the UML diagram below This is a simplified version of a class diagram known as a "UML diagram" or "Unified Modeling Language diagram". These types of diagrams are commonly used during the software engineering design process when programmers are first building classes and client files. They are programming language independent. The following are some descriptions of the parts of a UML diagram: The + (plus sign) indicates the field or method is public The - (minus sign) indicates the field or method is private. Use private in place of public when declaring a field or method. The parameter list for a method is listed in parentheses using their proposed type. For this assignment, you should use the names given for any input parameters as specified in the decomposition. The return type is listed after the method (and after the semicolon).

Class Name

SongBase

Instance Variables (fields)

- title: String - artist: String - genre : int

Constructors

+ SongBase() + SongBase(String title, String artist, int genre)

Instance Methods

+ setTitle(String title) : void + setArtist(String artist) : void + setGenre(int genre) : void + getTitle() : String + getArtist() : String + getGenre() : int + getGenreName() : String + toString() : String + equals(Object other) : boolean

Decomposition Information for SongBase Class

You may add additional helper methods for a class if you wish, but the methods from the UML, described in more detail below must be included since they will be unit tested.

1. Constructors - There are two constructors in the base class. The default should initialize the instance variables to either the empty string "" for title and artist. It should initialize the genre to the value -1. The overloaded constructor should use the input parameters for initial values of the instance variables.
2. Accessor and Mutators - You should provide accessor and mutator methods for each of the instance variables in the base class.
3. public String getGenreName() - There are (3) genre options for any song -- Holiday, Romance and Party. Internally, the genre will be represented as an integer value (0 = Holiday, 1 = Dance, 2 = Romance). For a better user experience, the base class provides this method which retrieves the designated genre and converts it to its genre string name before returning it. If the genre is -1 this means no genre has been assigned in which case the empty string should be returned.
4. public String toString() - This method overrides the default toString() method for printing an object. You should customize it to return a string with the appropriate information for a SongBase object. Specifically, it should return a string suitable for printing in the following form
   Title: title
   Artist: artist
   Genre: genre name
   
   For example, if it were to be called from the client for the song, "White Christmas" by Bing Crosby, it would return a string like this:

5. boolean equals(Object other) - This method overrides the standard equals() method for comparing two song objects. Two song objects are considered equal if they have the same title (ignore case), artist (ignore case) and genre. Otherwise the song objects are not considered equal. Returns a boolean indicating whether or not two song objects are equal.

TIP: Build the Base Class first - You should build the base class first and devise a client that can test the base class much like we did in lecture. Once you feel pretty good about your base class, you can begin developing the PlaylistDerived Class next. You do NOT want to develop the entire application at once unless you have a strong desire to spend several days debugging your program.

Extending the Base Class with the PlaylistDerived Class:

The members of the PlaylistDerived class are listed below in the UML diagram. You must use the same field names and method names as listed in the diagram. This will insure that the included tests for the program will work for your implemented class.

Class Name

PlaylistDerived

Constants and Instance Variables (fields)

- MAXSIZE : int constant (max size of playlist is 8) - playlist (an array of song objects) : SongBase[MAXSIZE] - count (count of songs in the playlist): int

Constructors

+ PlaylistDerived()

Instance Methods

+ getCount() : int + addSong(String title, String artist, int genre) : int + removeSong(String title, String artist, int genre) : int + moveSongsUp(int position) : void + findSong(SongBase songtoFind) : int + customPlayList(String artist) : String + customPlayList(int genre) : String + toString() : String

Decomposition Information for PlayListDerived Class

You may add additional helper methods for a class if you wish, but the methods from the UML, described in more detail below must be included since they will be unit tested.

1. Constructors There is one default constructor. The default should initialize the instance variable count to the value of 0.
2. public int getCount() - This accessor method returns the current count of songs in the playlist.
3. public int addSong(String title, String artist, int genre) - This method adds a new song to the playlist at the next available location in the playlist array and updates the instance variable count by 1. For example, if there are two songs in the playlist, then the new song should be added at location 2 and the count should be incremented to 3 (remember that the first song is in location 0 of the array). This method should return a 0 if the song is successfully added and return a -1 if this song is a duplicate that already exists in the playlist. You should use the helper method findSong() when looking for a duplicate song. Data Validation: If the playlist array is full, throw an ArrayIndexOutOfBoundsException that states "Cannot add: " + title of song + " Maximum playlist size is " + MAXSIZE.
4. public int removeSong(String title, String artist, int genre) - This method removes a specific song from the playlist and decrements the count of songs in the playlist by 1. Keep in mind that to "remove" a song from the array, we don't actually delete it, we simply move up all the subsequent songs in the playlist by one position and basically overwrite the song that was to be deleted. This method should return a 0 if the song is successfully deleted and returns a -1 if this song is not in the playlist and therefore cannot be deleted. You should use the helper method findSong() when looking for whether or not the song exists to delete and the helper method moveSongsUp() to adjust the playlist after removing a song from it.
5. public void moveSongsUp(int position) - This helper method helps the removeSongs() method by moving up all the songs by one position in the playlist based on the position of the song that is to be "deleted".
6. public String customPlayList(String artist) - This method searches the playlist for all songs containing this artist's name (ignore case) in the artist field. Like the customPlayList(int genre), this overloaded method returns a String representing that playlist but is based on the artist's name instead of genre type. Data Validation: If no songs are found by the requested artist, the method should return the string "No songs by this artist found". For more information, see sample run.
7. public String customPlayList(int genre) - This overloaded method searches the playlist for all songs of a given genre and returns a String representing that playlist. Data Validation: If no songs are found in the requested genre, the method should return the string "No songs in this genre found". For more information, see sample run.
8. public String toString() - This method overrides the default toString() method for printing an object. You should customize it to return a string with the appropriate information for a complete playlist by repeatedly calling the base class toString() method. Specifically, it should return a string suitable for printing in the following form (see sample run for more examples):

TIP: Build this class after the base class - You should build the PlayList class after building the base class and devise a client that can test the PlayList class much like we did in lecture. Once you feel good about your PlayList class, you can start developing the client application.

Building the Client Test Program:

The client program you develop is simply going to be a test driver. In other words, it should thoroughly test your base and derived class. Since you've not had prior experience doing this, we are providing the final test client for you. You may add lines, comment out lines or modify this as you wish to assist you with any testing you perform during your development process and prior to submitting to zyBooks. Of course, zyBooks will also test almost every method to ensure that it follows the specs appropriately.

Sample Run (using the provided test client):

Answer 1

SongBase.java

public class SongBase {
private String title, artist;
private int genre;
  
public SongBase()
{
this.title = "";
this.artist = "";
this.genre = -1;
}

public SongBase(String title, String artist, int genre)
{
this.title = title;
this.artist = artist;
  
// if genre is not anyone of the following: 0, 1, 2, by default, it sets the genre to 0
if(genre != 0 && genre != 1 && genre != 2)
this.genre = 0;
else
this.genre = genre;
}

public String getTitle() {
return title;
}

public void setTitle(String title) {
this.title = title;
}

public String getArtist() {
return artist;
}

public void setArtist(String artist) {
this.artist = artist;
}

public int getGenre() {
return genre;
}

public void setGenre(int genre) {
this.genre = genre;
}
  
public String getGenreName()
{
String res;
if(this.genre == -1)
res = "";
else
{
switch(this.genre)
{
case 0:
res = "Holiday";
break;
  
case 1:
res = "Dance";
break;
  
case 2:
res = "Romance";
break;
  
default:
res = "";
}
}
return res;
}
  
@Override
public String toString()
{
return("Title: " + this.title + "\n"
+ "Artist: " + this.artist + "\n"
+ "Genre: " + getGenreName());
}
  
@Override
public boolean equals(Object other)
{
if(other instanceof SongBase)
return (this.title.equalsIgnoreCase(((SongBase) other).getTitle())
&& this.artist.equalsIgnoreCase(((SongBase) other).getArtist())
&& getGenreName().equalsIgnoreCase(((SongBase) other).getGenreName()));
else
return false;
}
}

PlaylistDerived.java

public class PlaylistDerived extends SongBase{
private static final int MAXSIZE = 8;
private SongBase playlist[] = new SongBase[MAXSIZE];
private int count;
  
public PlaylistDerived()
{
this.count = 0;
}
  
public int getCount(){ return this.count; }
  
public int addSong(String title, String artist, int genre)
{
if(count == MAXSIZE)
throw new ArrayIndexOutOfBoundsException("Cannot add: " + title
+ " Maximum playlist size is " + MAXSIZE + ".");
  
SongBase song = new SongBase(title, artist, genre);
if(this.count == 0)
{
this.playlist[count] = song;
this.count += 1;
return 0;
}
else
{
if(findSong(song) == -1) // not duplicate
{
this.playlist[count] = song;
this.count += 1;
return 0;
}
else
return -1;
}
}
  
public int removeSong(String title, String artist, int genre)
{
SongBase song = new SongBase(title, artist, genre);
if(findSong(song) != -1)
{
int position = findSong(song);
moveSongsUp(position);
this.count -= 1;
return 0;
}
else
return -1;
}
  
public String customPlaylist(String artist)
{
String res = "";
  
for(int i = 0; i < count; i++)
{
if(this.playlist[i].getArtist().equalsIgnoreCase(artist))
res += this.playlist[i].toString() + "\n--------------------\n";
}
  
if(res.equals(""))
return "No songs by this artist found.";
else
return res;
}
  
public String customPlaylist(int genre)
{
String res = "";
  
for(int i = 0; i < count; i++)
{
if(this.playlist[i].getGenre() == genre)
res += this.playlist[i].toString() + "\n--------------------\n";
}
  
if(res.equals(""))
return "No songs in this genre found.";
else
return res;
}
  
public int findSong(SongBase songToFind)
{
int index = -1;
  
if(this.count == 0)
index = -1;
else
{
for(int i = 0; i < this.count; i++)
{
if(this.playlist[i].equals(songToFind))
{
index = i;
break;
}
}
}
return index;
}
  
public void moveSongsUp(int position)
{
for(int i = position; i < count - 1; i++)
{
this.playlist[i] = this.playlist[i + 1];
}
}
  
@Override
public String toString()
{
String res = "";
  
if(count == 0)
res = "Playlist is empty\n";
else
{
res = "My Playlist (count of songs = " + getCount() + ")\n\n";
for(int i = 0; i < count; i++)
{
if(i == count - 1)
res += (i + 1) + ". " + this.playlist[i].toString() + "\n";
else
res += (i + 1) + ". " + this.playlist[i].toString() + "\n\n";
}
}
return res;
}
}

SongsTester.java (Client?Driver class)

public class SongsTester {
  
public static void main(String[] args)
{
System.out.println("***** Testing creating new playlist *****");
  
PlaylistDerived playlist = new PlaylistDerived();
System.out.println(playlist);
  
System.out.println("\n***** Testing adding 6 songs *****");
playlist.addSong("White Christmas", "Bing Crosby", 0);
playlist.addSong("White Christmas", "Bedha Skolar", 0);
playlist.addSong("Jingle Java Christmas", "NaDHA Skolar", 0);
playlist.addSong("All I Want For Christmas is For Nadha To Pass", "The Skolar Family", 0);
playlist.addSong("Be My Java Bae", "NAdha Skolar", 1);
playlist.addSong("Sad Sitch", "Stellar Skolar", 0);
  
System.out.println(playlist);
  
System.out.println("\n***** Testing adding duplicate songs *****");
if(playlist.addSong("Be My Java Bae", "nadha SKOLAR", 0) == -1)
System.out.println("ERROR: Duplicate song Be My Java Bae (genre 0) not added");
else
System.out.println("SUCCESS: Song Be My Java Bae (genre 0) successfully added");
  
if(playlist.addSong("Be My Java Bae", "nadha SKOLAR", 0) == -1)
System.out.println("ERROR: Duplicate song Be My Java Bae (genre 0) not added");
else
System.out.println("SUCCESS: Song Be My Java Bae (genre 0) successfully added");
  
if(playlist.addSong("Jingle Java Christmas", "NaDHA Skolar", 0) == -1)
System.out.println("ERROR: Duplicate song Jingle Java Christamas (genre 0) not added");
else
System.out.println("SUCCESS: Song Jingle Java Christamas (genre 0) successfully added");
  
System.out.println("\n" + playlist);
  
  
  
System.out.println("\n***** Testing overflowing the playlist *****");
playlist.addSong("Jingly Java Christmas", "NADHA SKOLAR", 1);
playlist.addSong("AddMe4", "BEDHA SKOLLAR", 0);
  
System.out.println(playlist);
}
}

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