Java 5 Enum Typical Usage

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Declaration Example 1:

 

public enum Size { SMALL, MEDIUM, LARGE, EXTRA_LARGE };

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Declaration Example 2:

enum Size
{
   SMALL("S"), MEDIUM("M"), LARGE("L"), EXTRA_LARGE("XL");

   private Size(String abbreviation) { this.abbreviation = abbreviation; }
   public String getAbbreviation() { return abbreviation; }

   private String abbreviation;

 

   public static Size getFromAAbbreviation(String abbreviation)

  {
     for(Size size : Size.values())

     if(size.getAbbreviation().equals(abbreviation) return size;

  }

}

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How to convert String to an Enum instance?

 

Size s = (Size) Enum.valueOf(Size.class, "SMALL");

 

or

 

Size s = Size.valueOf("SMALL");

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How to enumerate?

Size[] values = Size.values();
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Remember:

 

1) you never need to use equals for values of enumerated types. Simply use == to compare them. Since The class has exactly four instances—it is not possible to construct new objects.