I want to pass a function in my constructor and want to use in next. I also used VoidCallback instead of Function but the same error showing.... "The argument type 'Function' can't be assigned to the parameter type 'void Function()'"

  ```  import 'package:flutter/material.dart';

class MyTextField extends StatelessWidget {
  const MyTextField({Key? key, required this.label,required this.onChanged}) : super(key: 
   key);
  final String label;
  final VoidCallback onChanged;

  @override
  Widget build(BuildContext context) {
    return TextField(
      style: const TextStyle(color: Colors.black),
      onChanged: onChanged,
      decoration:  InputDecoration(
        hintText: label,
        hintStyle: const TextStyle(color: Colors.grey),
        contentPadding: const EdgeInsets.symmetric(vertical: 10.0, horizontal: 20.0),
        border: const OutlineInputBorder(
          borderRadius: BorderRadius.all(Radius.circular(32.0)),
        ),
        enabledBorder: const OutlineInputBorder(
          borderSide:
          BorderSide(color: Colors.lightBlueAccent, width: 1.0),
          borderRadius: BorderRadius.all(Radius.circular(32.0)),
        ),
        focusedBorder: const OutlineInputBorder(
          borderSide:
          BorderSide(color: Colors.lightBlueAccent, width: 2.0),
          borderRadius: BorderRadius.all(Radius.circular(32.0)),
        ),
      ),
    );
  }
}

CodePudding user response：

instead

final VoidCallback onChanged;

use

   ValueChanged<String> onChanged;

e.g

class MyTextField extends StatelessWidget {
  const MyTextField({Key? key, required this.label,required this.onChanged}) : super(key: 
   key);
  final String label;
  final ValueChanged<String> onChanged;

  @override
  Widget build(BuildContext context) {
    return TextField(
      style: const TextStyle(color: Colors.black),
      onChanged: onChanged,
      decoration:  InputDecoration(
        hintText: label,
        hintStyle: const TextStyle(color: Colors.grey),
        contentPadding: const EdgeInsets.symmetric(vertical: 10.0, horizontal: 20.0),
        border: const OutlineInputBorder(
          borderRadius: BorderRadius.all(Radius.circular(32.0)),
        ),
        enabledBorder: const OutlineInputBorder(
          borderSide:
          BorderSide(color: Colors.lightBlueAccent, width: 1.0),
          borderRadius: BorderRadius.all(Radius.circular(32.0)),
        ),
        focusedBorder: const OutlineInputBorder(
          borderSide:
          BorderSide(color: Colors.lightBlueAccent, width: 2.0),
          borderRadius: BorderRadius.all(Radius.circular(32.0)),
        ),
      ),
    );
  }
}

CodePudding user response：

because VoidCallback not the same type as Type of onChanged in text filed so

change

final VoidCallback onChanged;

to

final void Function(String)? onChanged;