Music Player with BlueJ

Class yang dibutuhkan

MusicOrganizer,
dan MusicPlayer

Sourcecodes

Class MusicOrganizer

/**   
   * @version Y   
  */   
 import java.util.ArrayList;  
 public class MusicOrganizer   
 {    
   private ArrayList<String> files;   
   private MusicPlayer player;   
   public MusicOrganizer()   
   {   
     files = new ArrayList<String>();   
     player = new MusicPlayer();   
   }   
   public void addFile(String filename)   
   {files.add(filename);}   
   public int getNumberOfFiles()   
   {return files.size();}   
   public void listFile(int index)   
   {   
     if(index >= 0 && index < files.size())   
     {   
       String filename = files.get(index);   
       System.out.println(filename);   
     }   
   }   
   public void listAllFiles()   
   {   
     int i=0;   
     for(String filename : files)  
     {   
       System.out.println(i+": "+filename);   
       i++;   
     }   
   }   
   public void removeFile(int index)   
   {   
     if(index >= 0 && index < files.size())   
     {files.remove(index);}   
      }   
   public void startPlaying(int index)   
   {   
     if(validIndex(index))  
     {   
       String filename = files.get(index);   
       player.startPlaying(filename);   
     }   
   }   
   public void playAndWait(int index)   
   {   
     if(validIndex(index))  
     {   
       String filename = files.get(index);   
       player.startPlaying(filename);   
     }   
   }   
   public boolean validIndex(int index)   
   {   
     boolean valid;   
     if(index<0)  
     {   
       System.out.println("Index cannot be negative: "+index);   
       valid = false;   
     }   
     else if(index>= files.size())  
     {   
       System.out.println("Index is too large: "+ index);   
       valid=false;   
     }   
     else  
     {valid = true;}   
     return valid;   
   }   
  }

Class MusicPlayer

/**   
   * @version Y   
  */    
 public class MusicPlayer   
 {   
   private String Music;   
   public MusicPlayer()  
   {Music = "Tidak ada Lagu";}   
   public void startPlaying(String filename)   
   {   
    Music = filename;   
    System.out.println("Sedang memutar Lagu: "+Music);   
   }   
 }