API to Implement

For this homework, create:

a Playable interface

a PlayList class, and

a Song class

They must meet the APIs listed below. You may add additional methods to each class, if you wish (not required).

Playable Interface

public interface Playable

Create a Java interface named Playable that includes the following methods (and only the following methods):

public void play();

public String getName(); // returns the name (for PlayList) or title (for Song) of Playable object.

public int getPlayTimeSeconds(); // For Song: returns the number of seconds in the song. For PlayList: returns the number of seconds in the entire PlayList

public int numberOfSongs(); // For Song: returns 1. For PlayList returns the number of songs in the playlist and all playlists contained within.

Note: when writing getPlayTimeSeconds() and numberOfSongs() in the playlist class it can helpful to know that since both Playlist and Song implement theses methods it doesn't matter what the type of the object is when calling this method.

Both the Song and PlayList classes will implement this interface.

Song Class

public class Song

private String artist // the artist performing the song

private String title // the title of the song

private int minutes // number of min in length

private int seconds // number of seconds of length of the song (always less than 60)

// Add Getters / Setters for all fields

// Add the following three constructors (remember to initialize ALL fields in each of the constructors - regardless of the number of parameters!)

public Song(String artist, String title)

public Song(String artist, String title, int minutes, int seconds)

public Song(Song s)

public boolean equals(Object o) // a song is equal if all four fields are equal

public String toString() { // Use this code for toString EXACTLY

return "{Song: title = " + title + " artist = " + artist + "}";

}

public void play() { // Use this code for play EXACTLY

System.out.printf("Playing Song: artist = %-20s title = %s ", artist, title);

}

Make the Song class implement the interface Comparable, and make the ordering criteria as follows: Songs will be ordered by artist in ascending order. If the artists are the same, then by title in ascending order. If both artist and title are the same, then any order is acceptable.

Dont forget to include any methods needed to implement the Playable interface.

PlayList Class

public class PlayList

private String name // contains the name of the playlist

private ArrayList playableList // ArrayList of Playable elements that make up the play list

Methods that modify the list should return a boolean return true if they successfully change the list, otherwise they return false. Note that a PlayList can contain other PlayLists!

Methods that return a Playable element return null if they fail to find the song in question.

// Add Getters / Setters for name and songList

// Add a toString() method that returns the name of the playlist followed by its contents (by calling toString() on each item it contains). You should only have one name/title per line

// Add the following two constructors (remember to initialize ALL fields in each of the constructors - regardless of the number of parameters!)

public PlayList() // empty play list named "Untitled"

public PlayList(String newName) // empty play list

public boolean loadSongs(String fileName) // loads songs from file, more on this below

public boolean clear() // removes all playable elements in the play list

public boolean addSong(Song s) // adds Song s to the end of the play list

public Playable removePlayable(int index) // removes Playable element at index from the list and returns it

public Playable removePlayable(Playable p) // removes every occurrence of Playable p from the list and returns p

public Playable getPlayable(int index) // returns the Playable element at the appropriate index

public boolean addPlayList(PlayList pl) //adds the PlayList that is being passed to the end of the playableList and returns true unless the playableList already contains a playlist with the same name, in this case do not add the playlist and return false. Playlists are uniquely identified by name, so your program should not allow there to be two playlists with the same name.

public void play() // plays the play list by calling play() on each item in the play list in order

Write a method in PlayList called sortByName(). This method will sort the Playable items by the value returned by getName() in ascending order.

You must use a comparator object with Collections.sort() to achieve this. The interface to implement is Comparator.

Also add a method sortByTime() in PlayList that sorts by the Song or PlayList's total time in seconds, in ascending order (shortest first). It also must use a comparator object to achieve this. That object will use one of the methods in the Playable interface to get the time for each object.

Dont forget to include any methods needed to implement the Playable interface.

Data Input Format for PlayList.loadSongs() :

The data file that loadSongs() must process will have a simple format. There will be a total of 4 lines for each song, where the fourth line is always blank. (This means there will be one blank line at the end of the file.) The 1st line will be the song title; the 2nd line will be the artist; and the 3rd line will be the song's duration in the form M:SS or MM:SS.

Note that artist and title may be made up of multiple words separated by blanks. You must remove any leading or trailing blanks from any of these lines, if they are found.

Regarding the time format, there will not be any spaces inside the time-value. Either the minutes or seconds may be more or less than two characters. If the integer value for seconds is >= 60, then your code must determine the proper values of minutes and seconds-less-than-60 to store in the Song object.

Below is an example file. Be sure to create your own simple test files to test all possible wrinkles. Note the 2nd song has two lines that have leading spaces. Note that the 2nd song has a time-value of 1:135, which should be stored in the Song object as 3 minutes and 15 seconds. Note there is a final blank line in the file.

Testing

You will need to write at least 2 JUnit tests for each method above, this includes methods requried for for the Playable interface but exculdes getters and setters (no tests required for getters and setters although you can write some if you would like!) You will need to submit these to Web-Cat along with the rest of your code. Use standard naming conventions for these JUnit tests, however we do not mind what you call them. Remember, it would be best if you do not have more than one assert statement per JUnit test case (method). There is no upper limit on how many JUnit test cases you write. Place all your JUnit test cases in one single file ("JUnit Test Case") - you do not need separate files to test.

Make sure your JUnit test file has the word 'test' in it (e.g. TestHW4.java or PlayListTest.java, etc.)

Here is how the sample should look like

Dancing Queen Abba 4:13 Call Me Maybe Artie Jesperson and his Marching Polka Funk Ensemble 1:135