Question

This is my playlist class:

class Playlist{
  
   private String name;
   private int numberOfRecordings = 0;
   private int durationInSeconds = 0;
   private int MAX_PLAYLIST_SIZE;
   Recording recordingslist[];
  
   Playlist(){
       name = "Unknown";
       MAX_PLAYLIST_SIZE = 5;
       recordingslist = new Recording[MAX_PLAYLIST_SIZE];
       durationInSeconds = 0;
   }
  
   Playlist(String name, int size){
       this.name = name;
       this.MAX_PLAYLIST_SIZE = size;
       recordingslist = new Recording[MAX_PLAYLIST_SIZE];
       durationInSeconds = 0;
      
   }
  
   public String getName(){
       return this.name;
   }
  
   public int getNumberOfRecordings(){
       return this.numberOfRecordings;
   }
  
  
   public int getMAX_PLAYLIST_SIZE(){
       return this.MAX_PLAYLIST_SIZE;
   }
  
   public Recording[] getRecordings(){
       return recordingslist;
   }
  
   public void setName(String name){
       if(name!=null)
           this.name = name;
   }
  
   public boolean add(Recording r){
       if(r==null)
           return false;
      
       else if(numberOfRecordings>=MAX_PLAYLIST_SIZE)
           return false;
           recordingslist[numberOfRecordings]=r;
           numberOfRecordings++;
           durationInSeconds+=r.getDuration();
           return true;
   }
  
   public void play(){
       for(int i=0; i            recordingslist[i].play();
       }
   }
  
   @Override
   public String toString(){
           int s = durationInSeconds % 60;
           int h = durationInSeconds / 60;
           int m = h % 60;
           String str="";
           str+="\nPlaylist : "+name+" ["+m+"m"+s+"s]\n";
               for(int i=0;i                    str+=recordingslist[i]+"\n";
               }
               return str;
   }
          
}

Here is the Recording Class:

public class Recording{

   public String ARTIST;
   public String NAME;
   public int DURATION_IN_SECONDS;
     
   Recording(){
       ARTIST = "Unknown";
       NAME = "Unknown";
       DURATION_IN_SECONDS = 0;
   }
     
   Recording(String ARTIST, String NAME, int DURATION_IN_SECONDS){
       if (ARTIST != null && NAME != null && DURATION_IN_SECONDS >0){
           this.ARTIST = ARTIST;
           this.NAME = NAME;
           this.DURATION_IN_SECONDS = DURATION_IN_SECONDS;
       } else {
           this.ARTIST = "Unknown";
           this.NAME = "Unknown";
           this.DURATION_IN_SECONDS = 0;
       }
   }

  
   public String getArtist(){
       return this.ARTIST;
   }
  
   public String getName(){
       return this.NAME;
   }
  
   public int getDuration(){
       return this.DURATION_IN_SECONDS;
   }
  
   public void play(){
       if (DURATION_IN_SECONDS > 0){
           int s = DURATION_IN_SECONDS % 60;
           int h = DURATION_IN_SECONDS / 60;
           int m = h % 60;
          
       System.out.println("Now Playing:"+ARTIST+"-" +NAME+ "[" +m+"m" +s+"s]");
      
       }
       else {
           System.out.println("ERROR: cannot play this recording");
       }
   }
  
   @Override
   public String toString(){
           int s = DURATION_IN_SECONDS % 60;
           int h = DURATION_IN_SECONDS / 60;
           int m = h % 60;
       return ARTIST +"-"+NAME +"[" +m+"m" +s+"s]";
}
  

}

Please add the following to the playlist class:

• add a void shuffle method such that:

  • if the playlist is not empty, will RANDOMLY play numberOfRecordingsToPlay (an argument for shuffle method),

  • it is fine if if the same recording is played two or more times in a row,

• Add a void load method which:

  • will open a data file (fileName passed as an argument to this method),

    • Use try-catch to handle FileNotFoundException,

      • if caught display ERROR: File not found! Message, where fileName is a variable

    • File class does not have a close() method - don’t worry about closing it

Answer 1

Currently you are calling play() without any parameter and you don't have play() in your Recording so you cannot call recordinglist[i].play().

I have modified the play() and added the shuffle() method to the code.

Shuffle method will play the song number received in the argument.

Here are two methods:

public void play(Recording r){
for(int i=0; i<recordingslist.length;i++) {
   play(recordingslist[i]);
}
}

public void shuffle(int numberOfRecToPlay) {
   play(recordingslist[numberOfRecToPlay]);
}

To play random song on shuffle, you can pass random number while calling shuffle. You can do that using following code:

Random number = new Random();

song = number.nextInt(50)+1; // This will genarate random number from 1-51

suffle(song); // shuffle will play the song number passed as argument