final_initialized_in_declaration_and_constructor

'{0}' is final and was given a value when it was declared, so it can't be set to a new value.

The analyzer produces this diagnostic when a final field is initialized twice: once where it's declared and once by a constructor's parameter.

The following code produces this diagnostic because the field f is initialized twice:

class C {
  final int f = 0;

  C(this.f);
}

If the field should have the same value for all instances, then remove the initialization in the parameter list:

class C {
  final int f = 0;

  C();
}

If the field can have different values in different instances, then remove the initialization in the declaration:

class C {
  final int f;

  C(this.f);
}

Unless stated otherwise, the documentation on this site reflects Dart 3.8.0. Page last updated on 2025-05-08. View source or report an issue.