public void Play(string fileName) { string fileExtension = fileName.Substring(fileName.LastIndexOf('.')); if (fileExtension.Equals("vlc")) { advancedMediaPlayer = new VLCPlayer(); advancedMediaPlayer.PlayVls(fileName); } else if (fileExtension.Equals("mp4")) { advancedMediaPlayer = new MP4Player(); advancedMediaPlayer.PlayMP4(fileName); } }