Mimics a simple music player

MusicFile.txt

Blue Suede Shoes
Elvis Presley
Elvis Presley: Legacy Edition
With A Little Help From My Friends
The Beatles
Sgt. Pepper's Lonely Hearts Club Band
Seven Nation Army
The White Stripes
Elephant
Long Line Of Cars
Cake
Comfort Eagle
Head Like A Hole
Nine Inch Nails
Pretty Hate Machine

PlayList.java

public interface PlayList {

	public PlayListTrack getNextTrack();
		// Removes track from PlayList and returns it to the caller
		// Should return a null value if the PlayList is empty
	
	public PlayListTrack peekAtNextTrack();
		// Returns next entry to the caller, but leaves it in the list
	
	public void addTrack(PlayListTrack track);
		// Adds this track to the playlist in the appropriate order
	
	public boolean isEmpty();
		// Returns true if the playlist is empty
}

PlayListTrack.java

import java.util.Scanner;
public interface PlayListTrack {
	public String getName();
	public void setName(String name);
	public String getArtist();
	public void setArtist(String artist);
	public String getAlbum();
	public void setAlbum(String album);
	public boolean getNextTrack(Scanner infile);
		// Attempts to read a playlist track entry from a Scanner object
		// Sets the values in the object to the values given in
		// the file
		// If it successfully loads the track, return true
		// otherwise, return false
}

Project01.java

import java.io.File;
import java.io.FileNotFoundException;
import java.util.Scanner;

/**
 * 
 * @author Holly Leary
 * 
 */
public class Project01 {
	static PlayListTrack track = new SimpleMusicTrack();
	static Scanner infile = new Scanner(System.in);
	static SimplePlayList playList;
	public String selection = "null";
	public int trackInPlayCounter = 0;

	/**
	 * Manage playlists
	 */
	public Project01() {
		playList = new SimplePlayList(track);
		getFile();
		while (!(selection.equals("Q"))) {
			try{
				userInterface();
			} catch (Exception e){
				System.out.println("Ivalid entry. System shutting down.");
				System.exit(0);
			}
		}
	}

	/**
	 * Gets file from user; converts to tracks in a playlist
	 */
	public static void getFile() {
		System.out.print("Input filename:");
		String filename = infile.nextLine();
		File inputFile = new File(filename);
		Scanner file;
		try {
			file = new Scanner(inputFile);
			track.getNextTrack(file);
		
		} catch (FileNotFoundException e) {
			file = null;
			file.close();
			throw new IllegalArgumentException("You must enter a valid file.");
		}
		
		while (file.hasNext() == true) {
			PlayListTrack track = new SimpleMusicTrack();
			track.getNextTrack(file);
			playList.addTrack(track);
		}
	}
	
	public void selectionP(){
		track = playList.getNextTrack();
		this.trackInPlayCounter += 1;
	}
	
	public void selectionA(){
		System.out.println("Please enter track name:");
		String name = infile.nextLine();
		System.out.println("Enter artist name:");
		String artist = infile.nextLine();
		System.out.println("Enter album name:");
		String album = infile.nextLine();
		
		PlayListTrack newTrack = new SimpleMusicTrack(name, artist,
				album);
		System.out.println("New track: " + newTrack.getName());
		System.out.println("Artist: " + newTrack.getArtist());
		System.out.println("Album: " + newTrack.getAlbum());

		System.out.println("Are you sure you want to add this track [y/n]?");
		String validity = infile.nextLine();

		if ((validity.equals("y") || validity.equals("Y"))) {
			playList.addTrack(newTrack);
		} else {
			this.selection = "no selection";
		}
	}
	
	public void selectionQ(){
		System.out.println("Tracks remaining in playlist: ");
		playList.remainingTracks();
		System.out.println();
		this.selection = "Q";
		System.exit(0);
	}

	public void getSelection(){
		if (playList.songsinPlaylist() >= 1){
			System.out.println("[P]lay next track");
		}
		System.out.println("[A]dd a new track");
		System.out.println("[Q]uit");
		selection = infile.nextLine();
	}
	/**
	 * User playlist interface
	 */
	public void userInterface() {
		if ((selection != "P") && (selection != "p") && (selection != "A") && (selection != "a") && (selection != "Q") && (selection != "q") && (selection != null)){
			selection = null;
			userInterface();
		} else { 
			if (this.trackInPlayCounter == 0) {
				System.out.println("Currently playing: No Song Playing");
			} else if (playList.songsinPlaylist()+ 1 == 0){
				System.out.println("Currently playing: There are no songs remaining in playlist");
			} else {
				System.out.println("Currently playing: " + track.toString());
			}
			
			if (playList.songsinPlaylist() >= 1){
				System.out.println("Next track to play: " + playList.peekAtNextTrack());
			} else {
				System.out.println("Next track to play: No songs remaining in playlist");
			}
			
			getSelection();
		
		//If user selects "P"
		if ((selection.equals("p")) || (selection.equals("P"))) {
			selectionP();
	
		//If user selects "A"
		} else if ((selection.equals("a")) || (selection.equals("A"))) {
			selectionA();

		//If user selects "Q"
		} else if ((selection.equals("q")) || (selection.equals("Q"))) {
			selectionQ();
		}
		}
	}

	/**
	 * main
	 * 
	 * @param args
	 */
	public static void main(String[] args) {
		Project01 startProject01 = new Project01();
	}
}

SimpleMusicTrack.java

import java.util.Scanner;
import java.io.File;
import java.io.FileNotFoundException;

/**
 * @author Holly Leary
 * 
 */
public class SimpleMusicTrack implements PlayListTrack {
	private String album = null;
	private String artist = null;
	private String name = null;

	public SimpleMusicTrack() {
	}

	/**
	 * @param name
	 * @param artist
	 * @param album
	 */
	public SimpleMusicTrack(String name, String artist, String album) {
		setName(name);
		setArtist(artist);
		setAlbum(album);
	}

	public String getName() {
		return this.name;
	}

	public void setName(String name) {
		this.name = name;
	}

	public String getArtist() {
		return this.artist;
	}

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

	public String getAlbum() {
		return this.album;
	}

	public void setAlbum(String album) {
		this.album = album;
	}

	/**
	 * @param Scanner infile
	 * @return boolean
	 * 
	 *         Attempts to read playlist track entry from Scanner object 
	 *         Sets values in object to values given in file 
	 *         Returns value regarding success of track loading
	 */
	public boolean getNextTrack(Scanner infile) {
		try {
			this.name = infile.nextLine();
			this.artist = infile.nextLine();
			this.album = infile.nextLine();
			return this.equals(infile);
		} catch (Exception e) {
			return false;
		}
	}

	/**
	 * @param obj
	 * @return boolean: are two tracks the same, or is there a failure?
	 */
	public boolean equals(Object obj) {
		try {
			if (obj instanceof SimpleMusicTrack) {
				if ((this.name == ((SimpleMusicTrack) obj).getName())
						&& (this.artist == ((SimpleMusicTrack) obj).getArtist())
						&& (this.album == ((SimpleMusicTrack) obj).getAlbum())) {
					return true;
				}
			}
			return false;
		} catch (Exception e){
			return false;
		}
	}

	/**
	 * @return String in 'Artist / Song' format
	 */
	public String toString() {
		return "'" + getArtist() + " / " + getName() + "'";
	}
}

SimplePlayList.java

import java.io.FileNotFoundException;
import java.util.ArrayList;

/**
 * 
 * @author Holly Leary
 * 
 */
public class SimplePlayList implements PlayList {
	public ArrayList<PlayListTrack> list = new ArrayList<PlayListTrack>();

	public SimplePlayList(PlayListTrack track) {
		addTrack(track);
	}

	/**
	 * @return PlayListTrack to caller; removes track from playlist 
	 * Should return a null value if the PlayList is empty
	 */
	public PlayListTrack getNextTrack() {
		PlayListTrack track;
		track = this.list.get(0);
		this.list.remove(0);
		return track;
	}

	/**
	 * @returns next PLayListTrack entry to the caller, but leaves it in the list
	 */
	public PlayListTrack peekAtNextTrack() {
		return this.list.get(0);
	}

	/**
	 * Prints and removes remaining tracks from playlist
	 */
	public void remainingTracks() {
		if (list.size() == 0) {
			System.out.println("No tracks remaining");
		} else {
			for (int i = 0; i < list.size(); i++) {
				System.out.print(i + 1 + ".) ");
				System.out.println(this.list.get(i).getArtist() + " / "
						+ this.list.get(i).getName() + " / "
						+ this.list.get(i).getAlbum());
			}
			list.clear();
		}
	}

	/**
	 * @param track
	 *            : adds this track to playlist in appropriate order
	 */
	public void addTrack(PlayListTrack track) {
		this.list.add(track);
	}

	/**
	 * @return boolean: is playlist empty?
	 */
	public boolean isEmpty() {
		if (this.list.size() >= 1) {
			return true;
		} else {
			return false;
		}
	}
	public int songsinPlaylist(){
		int quantity = list.size();
		return quantity;
}
}

Hello, Holly. I'm an instructor for CSE 2123 (Data Structures Using Java) at OSU. This is the solution to a homework problem that we still use for that course. To discourage plagiarism, please remove this repository or make it private.