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JT Keller
JT Keller
12,731 Points

My Addition to the Karaoke Application

This isn't really a question. I thought that I would just share some minor code additions to the exercise and provide some food for thought.

liked the idea of the Karaoke application, but it didn't make much sense to me why you would enter URLs for songs and that information not be actionable so I added some code to start the video playing in the system's default browser. I'll probably play around with this a bit more, but I just wanted to share what I had.

package com.treehouse;

import java.awt.Desktop;
import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStreamReader;
import java.net.URI;
import java.net.URISyntaxException;
import java.util.ArrayDeque;
import java.util.ArrayList;
import java.util.HashMap;
import java.util.List;
import java.util.Map;
import java.util.Queue;

import com.treehouse.model.Song;
import com.treehouse.model.SongBook;

public class KaraokeMachine {
    private SongBook mSongBook;
    private BufferedReader mReader;
    private Map<String, String> mMenu;
    private Queue<Song> mSongQueue;
    Desktop desktop;

    public KaraokeMachine(SongBook songBook) {
        mSongBook = songBook;
        mReader = new BufferedReader(new InputStreamReader(System.in));
        mMenu = new HashMap<String, String>();
        mSongQueue = new ArrayDeque<Song>();
        mMenu.put("add", "Add a new song to the song book");
        mMenu.put("choose", "Choose a song to sing!");
        mMenu.put("play", "Play the next song in the queue");
        mMenu.put("quit", "Give up. Exit the program");
        desktop = Desktop.getDesktop();

    private String promptAction() throws IOException {
        System.out.printf("There are %d songs available and %d in the queue. Your options are: %n", mSongBook.getSongCount(), mSongQueue.size());
        for (Map.Entry<String, String> option : mMenu.entrySet()) {
            System.out.printf("%s - %s %n", option.getKey(), option.getValue());
        System.out.print("What do you want to do: ");
        String choice = mReader.readLine();
        return choice.trim().toLowerCase();

    public void run() {
        String choice = "";
        do {
            try {
                choice = promptAction();
                switch (choice) {
                case "add":
                    Song song = promptNewSong();
                    System.out.printf("%s added! %n%n", song);
                case "choose":
                    String artist = promptArtist();
                    Song artistSong = promptSongForArtist(artist);
                    System.out.printf("You chose: %s %n", artistSong);
                case "play":
                case "quit":
                    System.out.println("Thanks for playing!");
                    System.out.printf("Unknown choice: '%s'. Try again. %n%n%n", choice);
            } catch (IOException e) {
                System.out.println("Problem with input");
            } catch (URISyntaxException e) {
                System.out.println("The link that you entered for your song isn't a valid URL");
        } while (!choice.equals("quit"));

    private Song promptNewSong() throws IOException {
        System.out.print("Enter the artist's name: ");
        String artist = mReader.readLine();
        System.out.print("Enter the title: ");
        String title = mReader.readLine();
        System.out.print("Enter the video URL: ");
        String videoUrl = mReader.readLine();
        return new Song(artist, title, videoUrl);

    private String promptArtist() throws IOException {
        System.out.println("Available artists: ");
        List<String> artists = new ArrayList<String>(mSongBook.getArtists());
        int index = promptForIndex(artists);
        return artists.get(index);

    private Song promptSongForArtist(String artist) throws IOException {
        List<Song> songs = mSongBook.getSongsForArtist(artist);
        List<String> songTitles = new ArrayList<String>();
        for (Song song : songs) {
        System.out.printf("Available songs for %s: %n", artist);
        int index = promptForIndex(songTitles);
        return songs.get(index);


    private int promptForIndex(List<String> options) throws IOException {
        int counter = 1;
        for (String option : options) {
            System.out.printf("%d.) %s %n", counter, option);
        System.out.print("Your choice: ");
        String optionAsString = mReader.readLine();
        int choice = Integer.parseInt(optionAsString.trim());
        return choice - 1;

    public void playNext() throws IOException, URISyntaxException {
        Song song = mSongQueue.poll();
        if (song == null) {
            System.out.println("Sorry there are no songs in the queue. Use choose from the menu to add some");
        } else {
            System.out.printf("%n%n%n Open %s to hear %s by %s %n%n%n", song.getVideoUrl(), song.getTitle(), song.getArtist());

    public void openDefaultBrowserForSong(String videoUrl) throws IOException, URISyntaxException {
        if (desktop.isSupported(Desktop.Action.BROWSE)) {
        desktop.browse(new URI(videoUrl));
        } else {
            System.out.println("Your system isn't currently configured to open URLs in your default browser");