صيغة switch بأسلوب السهم

مشكلة switch القديمة

أساسيات صيغة السهم

public class Main {
    public static void main(String[] args) {
        int day = 3;
        switch (day) {
            case 1 -> System.out.println("Monday");
            case 3 -> System.out.println("Wednesday");
            default -> System.out.println("Other day");
        }
    }
}

لا مزيد من break

public class Main {
    public static void main(String[] args) {
        char grade = 'B';
        switch (grade) {
            case 'A' -> System.out.println("Excellent");
            case 'B' -> System.out.println("Good");
            case 'C' -> System.out.println("Average");
            default -> System.out.println("Needs work");
        }
    }
}

أجسام الكتل

public class Main {
    public static void main(String[] args) {
        int code = 2;
        switch (code) {
            case 2 -> {
                System.out.println("Processing code 2");
                System.out.println("Done");
            }
            default -> System.out.println("Unknown");
        }
    }
}

استخدام switch مع String

public class Main {
    public static void main(String[] args) {
        String fruit = "apple";
        switch (fruit) {
            case "apple" -> System.out.println("Red or green");
            case "banana" -> System.out.println("Yellow");
            default -> System.out.println("Unknown fruit");
        }
    }
}

فرع default

public class Main {
    public static void main(String[] args) {
        int level = 99;
        switch (level) {
            case 1 -> System.out.println("Beginner");
            case 2 -> System.out.println("Intermediate");
            default -> System.out.println("Unknown level: " + level);
        }
    }
}

استخدام switch مع التعدادات

public class Main {
    enum Color { RED, GREEN, BLUE }
    public static void main(String[] args) {
        Color c = Color.GREEN;
        switch (c) {
            case RED -> System.out.println("Stop");
            case GREEN -> System.out.println("Go");
            case BLUE -> System.out.println("Calm");
        }
    }
}

استدعاء الدوال داخل الفروع

public class Main {
    static void greet(String who) {
        System.out.println("Hello, " + who);
    }
    public static void main(String[] args) {
        int who = 1;
        switch (who) {
            case 1 -> greet("Alice");
            case 2 -> greet("Bob");
            default -> greet("Stranger");
        }
    }
}

أوضح من if-else

public class Main {
    public static void main(String[] args) {
        int month = 4;
        switch (month) {
            case 12, 1, 2 -> System.out.println("Winter");
            case 3, 4, 5 -> System.out.println("Spring");
            case 6, 7, 8 -> System.out.println("Summer");
            default -> System.out.println("Autumn");
        }
    }
}

للتأثيرات الجانبية فقط

public class Main {
    public static void main(String[] args) {
        int n = 5;
        switch (n % 2) {
            case 0 -> System.out.println(n + " is even");
            case 1 -> System.out.println(n + " is odd");
        }
    }
}

قيم متعددة، وفرع واحد

public class Main {
    public static void main(String[] args) {
        char c = 'e';
        switch (c) {
            case 'a', 'e', 'i', 'o', 'u' -> System.out.println("Vowel");
            default -> System.out.println("Consonant");
        }
    }
}

تحقق سريع

مراجعة