如何在scala中创建一个额外的字段的枚举 [英] How do I create an enum in scala that has an extra field

问题描述

  public enum FlatFileHeaderMapping {
 
 HEADER_EL（1） ，
 HEADER_RESERVED1（5），
 HEADER_RESERVED2（2），
 HEADER_MESSAGE_TYPE（4）
 
 public final int fieldSize; 
 
 private FlatFileHeaderMapping（int fieldSize）{
 this.fieldSize = fieldSize; 
} 
 
} 
  

然后我可以使用它每行进入地图，然后通过此枚举访问地图中的键（如符号）

枚举没有我能看到的这个质量，而案例类不像枚举声明那样排序 - 所以不能用于匹配如上所示的记录布局。至少没有没有一个有序的收藏的支持。

我可能会缺少一些明显的东西，因此这个问题！

谢谢

Ray

解决方案

：/ 7098500142 / diy-exhaustive-checking-on-scala-enums

In Java I have something like this

public enum FlatFileHeaderMapping {

   HEADER_EL(1),
   HEADER_RESERVED1(5),
   HEADER_RESERVED2(2),
   HEADER_MESSAGE_TYPE(4)

   public final int fieldSize;

    private FlatFileHeaderMapping(int fieldSize) {
        this.fieldSize = fieldSize;
   }

}

which I can then use it place each line into a map and later access the keys in the map via this enum (like symbols)

Enumeration does not have this quality as far as I can see, and case classes are not ordered like the enum declarations - so cannot be used to match a record layout as shown above. At least not without the support of an ordered collection.

I could be missing something obvious, hence the question!

Thanks

Ray

解决方案

Here is an approach that works: http://klangism.tumblr.com/post/7098500142/diy-exhaustiveness-checking-on-scala-enums

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