Dart does not have a syntax for declaring interfaces . Class declarations are themselves interfaces in Dart. Classes should use the implements keyword to be able to use an interface. It is mandatory for the implementing class to provide a concrete implementation of all the functions of the implemented interface.
Read moreCan we create class of interface?
Yes, you can define a class inside an interface . In general, if the methods of the interface use this class and if we are not using it anywhere else we will declare a class within an interface.
Read more