我需要在 Flutter 中获取周末的日期（仅周五和周六）以及该月的第一天和最后一天的日期
\n这是我周末尝试过的方法，但它不起作用\xc2\xb4t：
\n var dateuntilfriday = DateTime.now();\n\n getFriday() async {\n if (dateuntilfriday.weekday == DateTime.friday) {\n dateuntilfriday.add(Duration(days: 0));\n print("1 Executed");\n } else if (dateuntilfriday.weekday == DateTime.saturday) {\n dateuntilfriday.subtract(Duration(days: 1));\n print("2 Executed");\n } else if (dateuntilfriday.weekday == DateTime.sunday) {\n dateuntilfriday.subtract(Duration(days: 2));\n print("3 Executed");\n } else if (dateuntilfriday.weekday == DateTime.monday) {\n dateuntilfriday.add(Duration(days: 4));\n print("4 Executed");\n } else if (dateuntilfriday.weekday == DateTime.tuesday) {\n dateuntilfriday.add(Duration(days: 3));\n print("5 Executed");\n } else if (dateuntilfriday.weekday == DateTime.wednesday) {\n …