unnecessary_final

Don't use final for local variables.

Use var, not final, when declaring local variables.

Per Effective Dart, there are two styles in wide use. This rule enforces the var style. For the alternative style that prefers final, enable prefer_final_locals and prefer_final_in_for_each instead.

For fields, final is always recommended; see the rule prefer_final_fields.

BAD:

void badMethod() {
  final label = 'Final or var?';
  for (final char in ['v', 'a', 'r']) {
    print(char);
  }
}

GOOD:

void goodMethod() {
  var label = 'Final or var?';
  for (var char in ['v', 'a', 'r']) {
    print(char);
  }
}

The unnecessary_final rule is incompatible with the following rules:

• prefer_final_locals
• prefer_final_parameters
• prefer_final_in_for_each

To enable the unnecessary_final rule, add unnecessary_final under linter > rules in your analysis_options.yaml file:

linter:
  rules:
    - unnecessary_final

If you're instead using the YAML map syntax to configure linter rules, add unnecessary_final: true under linter > rules:

linter:
  rules:
    unnecessary_final: true

Unless stated otherwise, the documentation on this site reflects Dart 3.7.0. Page last updated on 2025-01-27. View source or report an issue.