[Dart] Class - interface

void main() {
  GradeA kim = new GradeA('kim');
  kim.sayName();

  GradeB lee = new GradeB('lee');
  lee.sayName();
}

// 학생, 학생이름
class Student {
  String? name;

  void sayName() {}
}

class GradeA implements Student {
  String? name;

  GradeA(this.name);

  void sayName() {
    print('My name is ${this.name}');
  }
}

class GradeB implements Student {
  String? name;

  GradeB(this.name);

  void sayName() {
    print('My name is ${this.name}');
  }
}

--------------------------------------------[result]

My name is kim
My name is lee