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Java Java Data Structures Efficiency! Queueing

Lucas Frixione
Lucas Frixione
1,332 Points

I've been stuck for days with a problem i have no idea how to solve

i have followed the tutorials step by step and i can't figure out what is the problem, there are 4 and they are all related of that i'm sure: line 35:

error: ';' expected private String promptAction() throw IOException{

line 79:

error: ';' expected private Song promptNewSong() throw IOException{

line 89:

error: ';' expected private String promptArtist() throw IOException{

line 109:

error ';' expected private int promptForIndex(List<String> options)throw IOException{

at first i thought it was the import of java.io.IOException but i have imported it : here it goes the code

package com.teamtreehouse;
import com.teamtreehouse.model.SongBook;
import com.teamtreehouse.model.Song;
import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStreamReader;
import java.util.Map;
import java.util.HashMap;
import java.util.ArrayList;
import java.util.List;
import java.util.ArrayDeque;
import java.util.Queue;

public class KaraokeMachine{

  private SongBook mSongBook;
  private BufferedReader mReader;
  private Map<String,String> mMenu;
  private Queue<Song> mSongQueue;

  public KaraokeMachine(SongBook songBook){
 // esto convierte bytes a chars cuando realmente lo necesitamos
//para ayudar a la eficiencia
    mReader= new BufferedReader(new InputStreamReader(System.in));
    mSongQueue = new ArrayDeque<Song>();
    mMenu = new HashMap<String,String>();
    // los mapas string string sirven mucho para hacer menus
    mMenu.put("add","Add a new son to the song book");    
    mMenu.put("play","Play next song in the queue");
    mMenu.put("choose","Choose a song to sing!");
    mMenu.put("quit","Give up. Exit the program");

private String promptAction()throw IOException{
  //no es mi problema la exception
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();//trim recorta los espacios al final y al principio

  public void run(){
  String choice = "";
  do {
  choice = promptAction();//en vez de hacer ifs usamos switch
    case "add":
      Song song =promptNewSong();
      System.out.printf("%s has been added! %n%n",song);
        String artist = promptArtist();
        Song artistSong=promptSongForArtist(artist);
        //TODO: ADD TO A SONG QUEUE,done
        System.out.printf("you chose: %s %n",artistSong);
        case "play":
      case "quit":
      System.out.println("Thanks for playing!");
    default : 
      System.out.printf("unknown choice: '%s'. Try again.  %n%n%n",choice);
    }catch(IOException ioe){
    System.out.println("problem with input");

  private Song promptNewSong()throw 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 url =mReader.readLine();
  return new Song(artist,title,url);   

  private String promptArtist() throw IOException{
  System.out.println("Available artists: ");
    List<String> artists = new ArrayList<>(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<>();
  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)throw IOException{
  int counter = 1;
  for (String option : options){
  System.out.printf("%d.) %s %n",counter,option);
  counter ++;
   System.out.print("Your choice:  ");
 String optionAsString = mReader.readLine();
  int choice = Integer.parseInt(optionAsString.trim());
  return choice -1;

  public void playNext(){
  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()


please help me i cant move forward if i don't finish with this and i'm getting really frustrated, i really want to finish the course but it has been 5 days and still nothing, i believe the workspaces are extremely buggy and need tons of fixing

1 Answer

Seth Kroger
Seth Kroger
56,412 Points

Your function declarations use throw instead of throws. throw is the actual act of throwing an exception. In other words it's a code statement which is expected to end in a semi-colon. throws is what you want to use to say "It throws an exception."