Flutter 自定义View 构造参数写法，必传、选传_创建flutterview如何传参数-优快云博客

文章详细介绍了CustomDialogView类的使用，包括可选参数的处理、必传参数的要求，以及如何设置默认值和TextStyle。着重讲解了何时需要传递参数和何时可以省略，以及常量的使用规范。

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1、参数可以不传（优先）

CustomDialogView()

 CustomDialogView(title: "新标题",),

class CustomDialogView extends StatefulWidget {
  String title;
  String? titleStyle;

  CustomDialogView({super.key, this.title = "默认标题", this.titleStyle});

  @override
  State<CustomDialogView> createState() => _CustomDialogViewState();
}

class _CustomDialogViewState extends State<CustomDialogView> {
  @override
  Widget build(BuildContext context) {
    return Text(
      widget.title,
    );
  }
}

2、参数必传


 CustomDialogView(title: "新标题",),

class CustomDialogView extends StatefulWidget {
  String? title;
  String? titleStyle;

  CustomDialogView({super.key, this.title, this.titleStyle})
      : assert(title != null);

  @override
  State<CustomDialogView> createState() => _CustomDialogViewState();
}

class _CustomDialogViewState extends State<CustomDialogView> {
  @override
  Widget build(BuildContext context) {
    return Text(
      widget.title??"默认标题",
    );
  }
}

class CustomDialogView extends StatefulWidget {
  String title;
  String? titleStyle;

  CustomDialogView({super.key, required this.title, this.titleStyle});

  @override
  State<CustomDialogView> createState() => _CustomDialogViewState();
}

3、TextStyle 默认常量必须加 const

this.titleStyle = const TextStyle(fontSize: 12.0)});

4、content 是必传参数

class CustomDialogView extends StatefulWidget {
  String content;
  String title;
  TextStyle titleStyle;

  CustomDialogView(
      {super.key,
      required this.content,
      this.title = "默认标题",
      this.titleStyle = const TextStyle(fontSize: 12.0)});

  @override
  State<CustomDialogView> createState() => _CustomDialogViewState();
}

class _CustomDialogViewState extends State<CustomDialogView> {
  @override
  Widget build(BuildContext context) {
    return Text(
      widget.title,
      style: widget.titleStyle,
    );
  }
}