flutter - 命名参数不能以 null safe flutter 下划线开头

Question

我不确定为什么会失败？如何解决？

根据这个 https://dart.dev/tools/diagnostic-messages#private_optional_parameter 它被告知要使它们不带下划线。但这会使变量成为公共(public)变量而不是私有(private)变量？

class ContactElement extends StatelessWidget {


  final IconData _icon;
  final String _heading;
  final String _describer;

  const ContactElement({
    Key? key,
    required this._icon,
    required this._heading,
    required this._describer,
  }) : super(key: key);
}

请帮忙

Answer 1

下划线表示 Dart 的私有(private)字段 ( more here )

class ContactElement extends StatelessWidget {
  const ContactElement({
    Key? key,
    required IconData icon,
    required String heading,
    required String describer,
  }) : _icon = icon,
       _heading = heading,
       _describer = describer,
       super(key: key);
  
  // Private fields
  final IconData _icon;
  final String _heading;
  final String _describer;

  // If you want that other parts of the code could to these
  // fields, use getters and setters. Here is a getter example. 
  IconData get icon => _icon;
  ...
}