org.apache.avalon.framework

Class Enum

public abstract class Enum extends 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 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
Stringm_name
The string representation of the Enum.
Constructor Summary
protected Enum(String name)
Constructor to add a new named item.
protected Enum(String name, Map map)
Constructor to add a new named item.
Method Summary
booleanequals(Object o)
Tests for equality.
StringgetName()
Retrieve the name of this Enum item, set in the constructor.
inthashCode()
StringtoString()
Human readable description of this Enum item.

Field Detail

m_name

private final String m_name
The string representation of the Enum.

Constructor Detail

Enum

protected Enum(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(String name, 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(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

getName

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

Returns: the name String of this Enum item

hashCode

public int hashCode()

toString

public String toString()
Human readable description of this Enum item. For use when debugging.

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