Fields can't be initialized in the constructor if they are final and were already initialized at their declarationDRT-W1359

The analyzer produces this diagnostic when a final field is initialized in both the declaration of the field and in an initializer in a constructor. Final fields can only be assigned once, so it can't be initialized in both places.

Example

The following code produces this diagnostic because f is :

class C {
  final int f = 0;
  C() : f = 1;
}

Common fixes

If the initialization doesn't depend on any values passed to the constructor, and if all of the constructors need to initialize the field to the same value, then remove the initializer from the constructor:

class C {
  final int f = 0;
  C();
}

If the initialization depends on a value passed to the constructor, or if different constructors need to initialize the field differently, then remove the initializer in the field's declaration:

class C {
  final int f;
  C() : f = 1;
}