return the number of tracks in the collection . concode_field_sep Random random concode_elem_sep TrackReader reader concode_elem_sep ArrayList<Track> tracks concode_elem_sep MusicPlayer player concode_field_sep void listTrack concode_elem_sep void removeTrack concode_elem_sep void randomListOfSong concode_elem_sep boolean indexValid concode_elem_sep void playTrack concode_elem_sep void stopPlaying concode_elem_sep void playFirst concode_elem_sep void addTrack concode_elem_sep void readLibrary concode_elem_sep void listAllTracks concode_elem_sep void listByArtist concode_elem_sep void randomSong concode_elem_sep void addFile
int function ( ) { return tracks . size ( ) ; }