Scala / Java枚举 [英] Scala/Java enumerations

问题描述

我已阅读这个和此，但我仍然不明白（惯用语）

I've read this and this, but I still don't understand the (idiomatic) equivalent way to do this in Scala

enum Status { 
    OK(1, "Ok", "Okay"),
    NOT_OK(5, "Not Ok", "Not Okay")
    BAD(10, "Bad", "Run for your life")

    int code;
    String name;
    String description; // custom fields

    Status(int code, String name, String description) {
        this.code = code;
        this.name = name;
        this.description = description;
    }
}

class Main {
    public static void main(String[] args) {
        for(Status status : Status.values) { // iterate through them
            doStuff(status);
        }
    }

    private doStuff(Status status) {
        System.out.println(status.description);
        // and more
    }
}

推荐答案

在Scala中，您可以创建一个接近Java的枚举的枚举结构。基本上，您需要做的只是扩展 scala.Enumeration类，并且如果您需要更复杂的类作为枚举，则扩展Val类。否则，您可以使用默认的Val类，它使用Int或String或Both。下面是您的Java代码的Scala版本。

In Scala you can create a Enumeration structure which is close to "enum" from Java. Basically, what you need to do is just to extend a scala.Enumeration class and to extend a Val class if you need a more complicated class as a enum. Otherwise, you can use default Val class which takes Int or String or Both. Below, is a Scala version of your Java code.

object Status extends Enumeration {

  case class StatusVal(code: Int, name: String, description: String) extends Val

  val OK = StatusVal(1, "Ok", "Okay")
  val NOT_OK = StatusVal(1, "Not Ok", "Not Okay")
  val BAD = StatusVal(1, "Bad", "Run for your life")
}

object Application extends App {
  Status.values foreach (s => println(s.asInstanceOf[StatusVal].description))
}

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