谁能告诉我如何获取播放列表的成员数？我试过这个但它不起作用：
int PlayListCount = cursor.getInt(cursor.getColumnIndex(MediaStore.Audio.Playlists._COUNT));
它抛出这个异常：
llegalStateException: Couldn't read row 0, col -1 from CursorWindow.
Make sure the Cursor is initialized correctly before accessing data from it.