switch_on_type

Avoid switch statements on a 'Type'.

The analyzer produces this diagnostic when a switch statement or switch expression is used on either the value of a Type or a toString call on a Type.

The following code produces this diagnostic because the switch statement is used on a Type:

void f(Object o) {
  switch (o.runtimeType) {
    case const (int):
      print('int');
    case const (String):
      print('String');
  }
}

Use pattern matching on the variable instead:

void f(Object o) {
  switch (o) {
    case int():
      print('int');
    case String():
      print('String');
  }
}

Unless stated otherwise, the documentation on this site reflects Dart 3.8.0. Page last updated on 2025-05-20. View source or report an issue.