Enum

기존 방식

class Seasons {
    public static final Seasons SPRING = new Seasons();
    public static final Seasons SUMMER = new Seasons();
    public static final Seasons FALL   = new Seasons();
    public static final Seasons WINTER = new Seasons();
}

class Frameworks {
    public static final Frameworks DJANGO  = new Frameworks();
    public static final Frameworks SPRING  = new Frameworks();
    public static final Frameworks NEST    = new Frameworks();
    public static final Frameworks EXPRESS = new Frameworks();
}

적용 후

enum Seasons { SPRING, SUMMER, FALL, WINTER }
enum Frameworks { DJANGO, SPRING, NEST, EXPRESS }

Enum 활용 예제

적용 전

class Seasons {
    public static final Seasons SPRING = new Seasons();
    public static final Seasons SUMMER = new Seasons();
    public static final Seasons FALL   = new Seasons();
    public static final Seasons WINTER = new Seasons();
}

public class Main {
    public static void main(String[] args) {
        Seasons seasons = Seasons.SPRING;
        switch (seasons) {
            case Seasons.SPRING:
                System.out.println("봄");
                break;
            case Seasons.SUMMER:
                System.out.println("여름");
                break;
            case Seasons.FALL:
                System.out.println("가을");
                break;
            case Seasons.WINTER:
                System.out.println("겨울");
                break;
        }
    }
}

/*
출력값 
java: incompatible types: Seasons cannot be converted to int
*/

// 오류 이유:  switch문의 조건은 char, byte, short, int, Character, Byte, Short, Integer, String, enum 타입만 가능하지만, 위의 seasons는 사용자 정의 타입이기 때문입니다.

적용 후

enum Seasons {SPRING, SUMMER, FALL, WINTER}

public class Main {
    public static void main(String[] args) {
        Seasons seasons = Seasons.SPRING;
        switch (seasons) {
            case SPRING:
                System.out.println("봄");
                break;
            case SUMMER:
                System.out.println("여름");
                break;
            case FALL:
                System.out.println("가을");
                break;
            case WINTER:
                System.out.println("겨울");
                break;
        }
    }
}

//출력값 
봄