我试图通过使用像这样的add方法扩展列表
add
List<String> mylists = ['a', 'b', 'c']; var d = mylists.add('d'); print(d);
它给出了错误This expression has type 'void' and can't be used. print(d);
This expression has type 'void' and can't be used. print(d);
为什么我无法将列表保存在新变量中?谢谢