[230318 - TIL] Dart - class

속성와 메서드

• 메서드에 같은 이름의 변수가없으면 this를 사용하지않아도 해당 클래스의 속성에 접근 가능

    class Player {
      String name = 'dongwoo';
      int age = 30;

      void sayHello() {
        print("hello my name is $name");
      }
    }
   
    void main() {
       var player = Player();
      player.sayHello();
      player.name = 'new name';
      player.sayHello();
    }

constructor

• late를 통해 constructor에서 할당 가능- final을 통해 수정 불가능

    class Player {
      late final String name;
      late int age;

      Player(String name, int age) {
        this.name = name;
        this.age = age;
      }
     
      void sayHello() {
        print("hello my name is $name");
      }
    }
   
    void main() {
       var player = Player("dongwoo", 30);
      player.sayHello();
      player.name = 'new name';
      player.sayHello();  
    }
   
    // hello my name is dongwoo
    // Uncaught Error: LateInitializationError: Field 'name' has already been initialized.

constructor - 2 : positional arguments

	class Player {
      final String name;
      int age;

      Player(this.name, this.age);

      void sayHello() {
        print("hello my name is $name");
      }
    }

    void main() {
       var player = Player("dongwoo", 30);
      player.sayHello();
    //   player.name = 'new name';
    //   player.sayHello();
    }

constructor - 3 : named arguments

    class Player {
      final String name;
      int age;

      Player({
        required this.name, 
        required this.age
        });
    
      void sayHello() {
        print("hello my name is $name");
      }
    }
 
    void main() {
       var player = Player(
         name: "dongwoo", 
         age: 30,
       );
      player.sayHello();
    }

constructor - 4 : named constructor

    class Player {
      final String name;
      int age;
      String team;

      Player.createBluePlayer({
        required String name,
        required int age,
      }) :  this.name = name,
            this.age = age,
            this.team = "blue";

      Player.createRedPlayer({
        required String name,
        required int age,
      }) :  this.name = name,
            this.age = age,
            this.team = "red";

      void sayHello() {
        print("hello my name is $name");
      }
    }

    void main() {
       var player = Player.createBluePlayer(
          name: "dongwoo",
          age: 30,
       );

      var player2 = Player.createRedPlayer(
        name: "hani",
        age: 20,
      );

      player.sayHello();
      player2.sayHello();
    }

api data binding

    class Player {
      final String name;
      int age;

      Player.fromJson(Map<String, dynamic> playerJson) 
        : name = playerJson['name'],
          age = playerJson['age'];

      void sayHello() {
        print("hello my name is $name");
      }
    }

    void main() {
       var apiData = [
         {
           "name": "dongwoo",
           "age": 30,
         },{
           "name": "minji",
           "age": 20,
         },{
           "name": "hani",
           "age": 20,
         },
       ];
   
      apiData.forEach((playerJson) {
        var player = Player.fromJson(playerJson);
        player.sayHello();
      });
    }

cascade notation

    class Player {
      String name;
      int age;
      String team;
    
      Player({
        required String name,
        required int age,
        required String team,
      }) :  this.name = name,
            this.age = age,
            this.team = team;
   
      void sayHello() {
        print("hello my name is $name");
      }
    }
 
    void main() {
      var dongwoo = Player(
        name:"dongwoo", 
        age: 30, 
        team: "redvelvet")
        ..name = 'minji'
        ..age = 20
        ..team = "newjeans";   
    }

enum

    enum Team {redvelvet, newjeans}

    class Player {
      String name;
      int age;
      Team team;
     
      Player({
        required String name,
        required int age,
        required Team team,
      }) :  this.name = name,
            this.age = age,
            this.team = team;
     
      void sayHello() {
        print("hello my name is $name");
      }
    }
   
    void main() {
      var dongwoo = Player(
        name:"dongwoo", 
        age: 30, 
        team: Team.redvelvet)
        ..name = 'minji'
        ..age = 20
        ..team = Team.newjeans;
  
      dongwoo.sayHello();
    }

abstract class

    enum Team {redvelvet, newjeans}
   
    abstract class Human {
      void walk();
    }
  
    class Player extends Human {
      String name;
      int age;
      Team team;
 
      Player({
        required String name,
        required int age,
        required Team team,
      }) :  this.name = name,
            this.age = age,
            this.team = team;
 
      void sayHello() {
        print("hello my name is $name");
      }

      void walk() {
        print("player $name is walking...");
      }
    }

    class Coach extends Human {
      void walk() {
        print("coach is walking...");
      }
    }

    void main() {
      var dongwoo = Player(
        name:"dongwoo", 
        age: 30, 
        team: Team.redvelvet);
      var hani = Coach();  

      dongwoo.walk();
      hani.walk();
    }

inheritance

    enum Team {redvelvet, newjeans}

    class Human {
      final String name;
      Human(this.nenum Team {redvelvet, newjeans}

    class Human {
      final String name;
      Human({required this.name});
 
      void sayHello() {
        print("hello my name is $name");
      }
    }

    class Player extends Human {
      Team team;

      Player({
        required this.team,
        required String name,
      }) : super(name: name);

      @override
      void sayHello() {
        super.sayHello();
        print("hello my team is $team");
      }

    }

    void main() {
      var dongwoo = Player(
        team: Team.redvelvet,
        name: "dongwoo",
      );

      dongwoo.sayHello();
    });

      void sayHello() {
        print("hello my name is $name");
      }
    }

    class Player extends Human {
      Team team;

      Player({
        required this.team,
        required String name,
      }) : super(name);

    }

    void main() {
      var dongwoo = Player(
        team: Team.redvelvet,
        name: "dongwoo",
      );

      dongwoo.sayHello();
    }

mixins

    class Strong {
      final double strenghtLevel = 1500.99;
    }

    class QuickRunner {
      void runQuick() {
        print("ruuuuuuuuun!");
      }
    }

    class Tall {
      final double height = 1.99;
    }

    enum Team {redvelvet, newjeans}

    class Player with Strong, QuickRunner, Tall {
      Team team;

      Player({
        required this.team,
      });

      void sayHello() {
        print("hello my team is $team");
      }

    }

    class Horse with Strong, QuickRunner {}

    class Kid with QuickRunner {}

    void main() {
      var dongwoo = Player(
        team: Team.redvelvet,
      );

      dongwoo.sayHello();
      dongwoo.runQuick();
      print(dongwoo.height);
    }

참고

노마드코더 - Dart 시작하기 (무료강의)