Intro Extended Switch Expressions

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Intro Extended Switch Expressions

這篇介紹Extended Switch Expressions。

Example

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Java17的switch可以接收回傳值並不需使用break來增加可讀性。

DayOfWeek dayOfWeek = LocalDate.now().getDayOfWeek();
boolean freeDay = switch (dayOfWeek) {
    case MONDAY, TUESDAY, WEDNESDAY, THURSDAY, FRIDAY -> false;
    case SATURDAY, SUNDAY -> true;
};

允許使用yield回傳值，且使用一個function來執行其它程式碼語法。

DayOfWeek dayOfWeek = LocalDate.now().getDayOfWeek();
boolean freeDay = switch (dayOfWeek) {
    case MONDAY, TUESDAY, WEDNESDAY, THURSDAY, FRIDAY -> {
      System.out.println("Work work work");
      yield false;
    }
    case SATURDAY, SUNDAY -> {
      System.out.println("Yey, a free day!");
      yield true;
    }
};