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org.apache.avalon.framework
Class Enum

java.lang.Object
  org.apache.avalon.framework.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 2004-09-11 03:16:39Z niclas $

Author:

Avalon Development Team

Constructor Summary

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

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

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.

Parameters:

o - the other object

Returns:

the equality status

hashCode

public int hashCode()

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.

Returns:

String in the form type[name], eg.: Color[Red].