dart he default constructor is already defined. Try giving one of the constructors a name. code example
Example: dart he default constructor is already defined. Try giving one of the constructors a name.
In dart you can not have the same method/constructor name used several times
(even with different parameters).
In your case you can either use named constructor to define 2 constructors :
class FirstClass {
FirstClass() {}
FirstClass.withA(a) {}
}