Dartstuff

Main.dart

void main() {
  Animal bob = new Kitten();
  bob.grow();
  bob.grow();
  bob.birthday();
  
  print(bob.speak());
  Animal x = new Puppy();
  print(bob);
  
  print(x.speak());
}


abstract class Animal {
  int age;
  Animal() {
    this.age = 0;
    print("Animal in the house");
  }
  
  void grow() {
    age++;
  }
  
  birthday() {
    print("My Age is ${age}");
  }
  
  String speak();
  
  
}

class Kitten extends Animal {
  @override
  String speak() { 
      return 'Meow';
    }
}

class Puppy extends Animal {
   @override
  String speak() { 
      return 'Ruff';
    }
}