缺少“getter PreferredSize.child”的具体实现。 - 颤动

Question

我在为应用程序栏创建单独的类时收到错误

Missing concrete implementation of 'getter PreferredSize.child'.

这是我的代码：

import 'package:flutter/material.dart';

class CustomAppBar extends StatelessWidget implements PreferredSize {
  CustomAppBar({super.key});

  @override
  Size get preferredSize => Size.fromHeight(70);

  @override
  Widget build(BuildContext context) {
    return AppBar(
      title: Text('Calender'),
      centerTitle: true,
      actions: [Icon(Icons.settings)],
    );
  }
}