Package org.apache.avalon.framework

Class Enum

  • Direct Known Subclasses:
    ValuedEnum
    public abstract class Enum
extends java.lang.Object
    Basic enum class for type-safe enums. Should be used as an abstract base. For example: 
     import org.apache.avalon.framework.Enum;

 public final class Color extends Enum {
   public static final Color RED = new Color( "Red" );
   public static final Color GREEN = new Color( "Green" );
   public static final Color BLUE = new Color( "Blue" );

   private Color( final String color )
   {
     super( color );
   }
 }
    If further operations, such as iterating over all items, are required, the Enum(String, Map) constructor can be used to populate a Map, from which further functionality can be derived: 
     public final class Color extends Enum {
   static final Map map = new HashMap();

   public static final Color RED = new Color( "Red", map );
   public static final Color GREEN = new Color( "Green", map );
   public static final Color BLUE = new Color( "Blue", map );

   private Color( final String color, final Map map )
   {
     super( color, map );
   }

   public static Iterator iterator()
   {
     return map.values().iterator();
   }
 }

    NOTE: between 4.0 and 4.1, the constructors' access has been changed from public to protected. This is to prevent users of the Enum breaking type-safety by defining new Enum items. All Enum items should be defined in the Enum class, as shown above.

    Version:
    $Id: Enum.java 45862 2004-09-10 22:16:39 -0500 (Fri, 10 Sep 2004) niclas $
    Author:
    Avalon Development Team

    • Field Summary

      Fields 
      Modifier and Type Field Description
      private java.lang.String m_name
      The string representation of the Enum.

    • Constructor Summary

      Constructors 
      Modifier Constructor Description
      protected Enum​(java.lang.String name)
      Constructor to add a new named item.
      protected Enum​(java.lang.String name, java.util.Map map)
      Constructor to add a new named item.

    • Method Summary

      All Methods Instance Methods Concrete Methods 
      Modifier and Type Method Description
      boolean equals​(java.lang.Object o)
      Tests for equality.
      java.lang.String getName()
      Retrieve the name of this Enum item, set in the constructor.
      int hashCode()  
      java.lang.String toString()
      Human readable description of this Enum item.

      • Methods inherited from class java.lang.Object

        clone, finalize, getClass, notify, notifyAll, wait, wait, wait

    • Field Detail

      • m_name

        private final java.lang.String m_name
        The string representation of the Enum.

    • Constructor Detail

      • Enum

        protected Enum​(java.lang.String name)
        Constructor to add a new named item.

        Note: access changed from public to protected after 4.0. See class description.

        Parameters:
        name - Name of the item.

      • Enum

        protected Enum​(java.lang.String name,
               java.util.Map map)
        Constructor to add a new named item.

        Note: access changed from public to protected after 4.0. See class description.

        Parameters:
        name - Name of the item.
        map - A Map, to which will be added a pointer to the newly constructed object.

    • Method Detail

      • equals

        public boolean equals​(java.lang.Object o)
        Tests for equality. Two Enum:s are considered equal if they are of the same class and have the same names. The method is also declared final - I (LSutic) did this to allow the JIT to inline it easily.
        Overrides:
        equals in class java.lang.Object
        Parameters:
        o - the other object
        Returns:
        the equality status

      • hashCode

        public int hashCode()
        Overrides:
        hashCode in class java.lang.Object

      • getName

        public final java.lang.String getName()
        Retrieve the name of this Enum item, set in the constructor.
        Returns:
        the name String of this Enum item

      • toString

        public java.lang.String toString()
        Human readable description of this Enum item. For use when debugging.
        Overrides:
        toString in class java.lang.Object
        Returns:
        String in the form type[name], eg.: Color[Red].