자바 코딩 / 조건문 프로그래밍 switch ~ case ~ default 사용 방법

날짜:

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public class App {
    public static void main(String[] args) throws Exception {

        System.out.println("\n---------- Start\n");

        String version = System.getProperty("java.version");
        String runtime = System.getProperty("java.runtime.version");
        String vendor = System.getProperty("java.vendor");

        System.out.println("Java Version : " + version);
        System.out.println("Runtime Version : " + runtime);
        System.out.println("Java Vendor : " + vendor);

        System.out.println("\n---------- End\n");
    }
}

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자바 실행 버전
자바 실행 버전

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import java.util.concurrent.ThreadLocalRandom;

public class App_02_Java_Version_int {
    public static void main(String[] args) throws Exception {

        System.out.println("\n---------- Start\n");

        /* 1 ~ 4 랜덤 */
        int rnd = ThreadLocalRandom.current().nextInt(1, 5);

        /* switch ~ case ~ default */
        switch (rnd) {
            case 1:
                System.out.println("숫자: " + rnd);
                break;
            case 2:
                System.out.println("숫자: " + rnd);
                break;
            case 3:
                System.out.println("숫자: " + rnd);
                break;
            default:
                System.out.println("기타 숫자: " + rnd);
        }

        System.out.println("\n---------- End\n");
    }
}

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자바 switch - int 조건 실행 결과
자바 switch - int 조건 실행 결과

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import java.util.concurrent.ThreadLocalRandom;

public class App_03_Java_Version_char {
    public static void main(String[] args) throws Exception {

        System.out.println("\n---------- Start\n");

        /* char 배열 */
        char[] arrChar = new char[] { 'A', 'B', 'C', 'D' };

        /* 0 ~ 3 랜덤 */
        int rnd = ThreadLocalRandom.current().nextInt(0, 4);

        /* switch ~ case ~ default */
        char valChar = arrChar[rnd];

        switch (valChar) {
            case 'A':
                System.out.println("선택된 문자: " + valChar);
                break;
            case 'B':
                System.out.println("선택된 문자: " + valChar);
                break;
            case 'C':
                System.out.println("선택된 문자: " + valChar);
                break;
            default:
                System.out.println("default - 기본 문자: " + valChar);
        }

        System.out.println("\n---------- End\n");
    }
}

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자바 switch - char 조건 실행 결과
자바 switch - char 조건 실행 결과

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import java.util.concurrent.ThreadLocalRandom;

public class App_04_Java_Version_string {
    public static void main(String[] args) throws Exception {

        System.out.println("\n---------- Start\n");

        /* String 배열 */
        String[] arrString = new String[] { "MON", "TUE", "WED", "THU", "FRI", "SAT", "SUN" };

        /* 0 ~ 7 랜덤 */
        int rnd = ThreadLocalRandom.current().nextInt(0, 7);

        /* switch ~ case ~ default */
        String valString = arrString[rnd];

        switch (valString) {
            case "MON":
                System.out.println("선택된 요일 MON: " + valString);
                break;
            case "TUE":
                System.out.println("선택된 요일 TUE: " + valString);
                break;
            case "WED":
                System.out.println("선택된 요일 WED: " + valString);
                break;
            case "THU":
                System.out.println("선택된 요일 THU: " + valString);
                break;
            case "FRI":
                System.out.println("선택된 요일 FRI: " + valString);
                break;
            case "SAT":
                System.out.println("선택된 요일 SAT: " + valString);
                break;
            default:
                System.out.println("기본 요일: " + valString);
                break;
        }

        System.out.println("\n---------- End\n");
    }
}

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자바 switch - String 조건 실행 결과
자바 switch - String 조건 실행 결과

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import java.util.concurrent.ThreadLocalRandom;

public class App_05_Java_Version_case_set {
    public static void main(String[] args) throws Exception {

        System.out.println("\n---------- Start\n");

        /* char 배열 */
        String[] arrString = new String[] { "MON", "TUE", "WED", "THU", "FRI", "SAT", "SUN" };

        /* 0 ~ 7 랜덤 */
        int rnd = ThreadLocalRandom.current().nextInt(0, 7);

        /* switch ~ case ~ default */
        String valString = arrString[rnd];

        switch (valString) {
            case "MON":
            case "TUE":
            case "WED":
            case "THU":
            case "FRI":
                System.out.println("주중: " + valString);
                break;
            case "SAT":
            case "SUN":
                System.out.println("주말: " + valString);
                break;
            default:
                System.out.println("기본 요일: " + valString);
                break;
        }

        System.out.println("\n---------- End\n");
    }
}

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자바 switch - case 집합 조건 실행 결과
자바 switch - case 집합 조건 실행 결과

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public class App {
    public static void main(String[] args) throws Exception {

        System.out.println("\n---------- Start\n");

        enum Day {
            MON, TUE, WED, THU, FRI, SAT, SUN
        }

        Day today = Day.FRI;

        switch (today) {
            case MON:
            case TUE:
            case WED:
            case THU:
            case FRI:
                System.out.println("주중입니다.");
                break;
            case SAT:
            case SUN:
                System.out.println("주말입니다.");
                break;
            default:
                break;
        }

        System.out.println("\n---------- End\n");
    }
}

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public class App {
    public static void main(String[] args) throws Exception {

        System.out.println("\n---------- Start\n");

        int day = 2;

        String result = switch (day) {
            case 1 -> "월요일";
            case 2 -> "화요일";
            case 3 -> "수요일";
            default -> "기타 요일";
        };

        System.out.println(result);

        System.out.println("\n---------- End\n");
    }
}

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public class App {
    public static void main(String[] args) throws Exception {

        System.out.println("\n---------- Start\n");

        int score = 85;

        String grade1 = switch (score / 10) {
            case 10, 9 -> "A";
            case 8 -> "B";
            case 7 -> "C";
            default -> {
                System.out.println("점수 낮음");
                yield "D";
            }
        };

        System.out.println(grade1);

        System.out.println("\n---------- End\n");
    }
}

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위치: 대한민국 서울특별시

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