Default initializer vs constructor

main.dart

class A {
  String value;
  A(this.value) { print(value); }
  String toString() => value;
}

class B {
  A a = A('Default');
  
  B();
  B.withANull() : this.a = null;
  B.withAInitList() : this.a = A('Init list');
  B.withAParam(this.a);
  B.withAConstruct() { this.a = A('Construct'); }
}

void main() {
  print('>>> B()');
  print(B().a);
  
  print('>>> B.withANull()');
  print(B.withANull().a);
  
  print('>>> B.withAInitList()');
  print(B.withAInitList().a);
  
  print('>>> B.withAParam()');
  print(B.withAParam(A('Param')).a);
  
  print('>>> B.withAConstruct()');
  print(B.withAConstruct().a);
}