[Flutter] Dart 문법 (abstract, implement)

 

 

 

* 추상클래스, implement : 추상클래스 및 일반 클래스 implement 가능.

- implement하면 클래스가 구현해 둔 메서드도 재정의 해야할 강제성이 생김. (일반 메서드도 구현해야 함)

class Spacecraft extends Describable {
  String? name;
  DateTime? launchDate;

  //Constructor, with syntactic sugar for assignment to members.
  Spacecraft(this.name, this.launchDate) {
    //Initialization code goes here.
  }

  Spacecraft.origin() {
    name = "무탈리스크";
    launchDate = DateTime.now();
  }

  //Named contructor that forwards to the default one.
  Spacecraft.unlaunched(String name) : this(name, null);

  int? get launchYear => launchDate?.year; //read-only non-final property

  //Method
  void describe() {
    print('Spacecraft: $name');
    if (launchDate != null) {
      int years = DateTime.now().difference(launchDate!).inDays ~/ 365;
      print('Launched: $launchYear ($years years ago)');
    } else {
      print('Unlaunched');
    }
  }
}

abstract class Describable {
  void describe();

  void describeWithEmphasis() {
    print('=========');
    describe();
    print('=========');
  }
}

//일반 클래스 implements시, 일반 메서드도 다 구현
class MyClass implements Spacecraft {
  @override
  DateTime? launchDate;

  @override
  String? name;

  MyClass(this.name);

  @override
  void describe() {
    print('#### Spacecraft: $name / Unlaunched ####');
  }

  @override
  void describeWithEmphasis() {}

  @override
  int? get launchYear => throw UnimplementedError();
}

void printShow(Spacecraft spacecraft) => spacecraft.describe();

void main() {
  Spacecraft sc = Spacecraft("스카우트", DateTime.now());
  sc.describeWithEmphasis();

  printShow(MyClass("ABC"));
}

//결과
=========
Spacecraft: 스카우트
Launched: 2021 (0 years ago)
=========
#### Spacecraft: ABC / Unlaunched ####

 

 

---

같이 보면 좋은 다른 포스팅

https://cording-cossk3.tistory.com/83

[Flutter] Dart 문법 (상속)

https://cording-cossk3.tistory.com/84

[Flutter] Dart 문법 (abstract, implement)

https://cording-cossk3.tistory.com/85

[Flutter] Dart 문법 (async, Future, await, then)

https://cording-cossk3.tistory.com/86

[Flutter] Dart 문법 (getter, setter)

https://cording-cossk3.tistory.com/87

[Flutter] Dart 문법 (json)