Interface in Dart

void main() {
  Drawable drawable1 = new Rectangle();
  drawable1.draw();

  Drawable drawable2 = new Circle();
  drawable2.draw();
}

class Drawable {
  void draw() {}
}

class Rectangle implements Drawable {
  void draw() {
    print("drawing rectangle");
  }
}

class Circle implements Drawable {
  void draw() {
    print("drawing circle");
  }
}
  

Output

drawing rectangle
drawing circle