Flutter勉強会3回目の資料(継承)

flutter_study_3rd_3.dart

void main() {
  Animal animal1 = Mike();
  print(animal1.breed);
  animal1.bark();
  
  Animal animal2 = Shiba();
  print(animal2.breed);
  animal2.bark();
  
  Animal animal3 = Stranger();
  print(animal3.breed);
  animal3.bark();
  
  Animal animal4 = Unknown();
  print(animal4.breed);
  animal4.bark();
  
}

class Animal {
  // field
  String breed = 'Animal';
  
  // method
  void bark() {
    print('I am Animal.');
  }
}

class Mike extends Animal {
  @override
  String breed = 'Cat';
  
  @override
  void bark() {
    print('meow');
  }
}

class Shiba extends Animal {
  
  get breed => 'Dog';
  set breed(String newValue) => breed = newValue;
  
  // overrideがなくても問題ない
  void bark() {
    print('bow-wow');
  }
}

class Stranger extends Animal {
  String breed = 'Human?';
  
  void bark() {
    // overrideがなくてもsuperを呼べる
    super.bark();
  }
}

class Unknown extends Animal {
  // overrideしなければ親の値が自動的に呼ばれる
}