有谁能告诉我如何获得播放列表的成员数量？我尝试了这个，但它不起作用：
int PlayListCount = cursor.getInt(cursor.getColumnIndex(MediaStore.Audio.Playlists._COUNT));
它引发了这个异常：
llegalStateException: Couldn't read row 0, col -1 from CursorWindow.
Make sure the Cursor is initialized correctly before accessing data from it.