Refined playlist loading:

- Removed intermediary collection.
- Filtered non-path metadata lines.

src/main/java/musicplayer/model/ExtractedMetadata.java

@@ -77,7 +77,8 @@ public class ExtractedMetadata {
         Tag audioTags = null;
         try {
             audioTags = AudioFileIO.read(targetFile.toFile()).getTag();
-        } catch (CannotReadException | IOException | ReadOnlyFileException | TagException | InvalidAudioFrameException ignored) {
+        } catch (CannotReadException | IOException | ReadOnlyFileException | TagException |
+                InvalidAudioFrameException | NullPointerException ignored) {
         }
         return audioTags == null ? Optional.empty() : Optional.of(new ExtractedMetadata(audioTags, targetFile.toFile()));
     }

src/main/java/musicplayer/playlist/IPlaylist.java

@@ -131,25 +131,40 @@ public interface IPlaylist {
      * @param targetFile File to read m3u playlist data from.
      * @return List of songs contained in the playlist.
      */
-    static List<Song> readPlaylistFromFile(File targetFile){
+    static List<Song> readPlaylistFromFile(final File targetFile){
         List<Song> result = new ArrayList<>();
         if(targetFile.exists()){
             try {
                 List<String> playlistData = Files.lines(targetFile.toPath()).filter(x -> !x.isEmpty() && !x.contains("#EXTINF")).collect(Collectors.toList());
                 if(playlistData.get(0).equals("#EXTM3U")){
                     playlistData.remove(0);
-                    List<Path> songPaths = playlistData.stream().map(Paths::get).collect(Collectors.toList());
+                    playlistData.stream().filter(x -> !x.startsWith("#")).map(Paths::get).map(x -> checkSongPath(x, targetFile)).map(ExtractedMetadata::autoParse)
-                    for(int i = 0; i < songPaths.size(); i++){
+                            .filter(Optional::isPresent).map(Optional::get).forEach(x ->
-                        if(!Files.exists(songPaths.get(i))){ // If song file doesn't exists, try treating it as relative
+                                    result.add(new Song(x.getTrackNumber(), x.getDiscNumber(), x.getTitle(),
-                            songPaths.set(i, Paths.get(targetFile.getParent(), songPaths.get(i).toString()));
+                                                new Artist(x.getArtist()), new Album(x.getAlbum()), x.getGenre(), x.getSongFile())));
-                        }
-                    }
-                    songPaths.stream().map(ExtractedMetadata::autoParse).filter(Optional::isPresent).map(Optional::get)
-                            .forEach(x -> result.add(new Song(x.getTrackNumber(), x.getDiscNumber(), x.getTitle(), new Artist(x.getArtist()), new Album(x.getAlbum()), x.getGenre(), x.getSongFile())));
                 }
             } catch (IOException ignored) { }
         }
         return result;
     }
 
+    /**
+     * Check whether a Path points to a valid file, if not try again under the assumption that the Path is instead
+     * relative instead of absolute. If neither then null is returned.
+     * @param targetFile Path to check if points to a valid file.
+     * @param playlistFile Playlist file being read (used to potentially transform paths to relative paths).
+     * @return A Path to a valid file or null.
+     */
+    static Path checkSongPath(final Path targetFile, final File playlistFile){
+        if(Files.exists(targetFile)){
+            return targetFile;
+        }
+        else{
+            Path alternateFile = Paths.get(playlistFile.getParent(), targetFile.toString());
+            if(Files.exists(alternateFile))
+                return alternateFile;
+        }
+        return null;
+    }
+
 }