Contents

prefer_void_to_null

Contents

Don't use the Null type, unless you are positive that you don't want void.

This rule is available as of Dart 2.1.

This rule has a quick fix available.

Details

#

DON'T use the type Null where void would work.

BAD:

dart
Null f() {}
Future<Null> f() {}
Stream<Null> f() {}
f(Null x) {}

GOOD:

dart
void f() {}
Future<void> f() {}
Stream<void> f() {}
f(void x) {}

Some exceptions include formulating special function types:

dart
Null Function(Null, Null);

and for making empty literals which are safe to pass into read-only locations for any type of map or list:

dart
<Null>[];
<int, Null>{};

Usage

#

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

analysis_options.yaml
yaml
linter:
  rules:
    - prefer_void_to_null