Package org.apache.avalon.framework

Class ValuedEnum

java.lang.Object

org.apache.avalon.framework.Enum

org.apache.avalon.framework.ValuedEnum

public abstract class ValuedEnum
extends Enum

Basic enum class for type-safe enums with values. Valued enum items can be compared and ordered with the provided methods. Should be used as an abstract base. For example:

 import org.apache.avalon.framework.ValuedEnum;

 public final class JavaVersion
   extends ValuedEnum
 {
   //standard enums for version of JVM
   public static final JavaVersion  JAVA1_0  = new JavaVersion( "Java 1.0", 100 );
   public static final JavaVersion  JAVA1_1  = new JavaVersion( "Java 1.1", 110 );
   public static final JavaVersion  JAVA1_2  = new JavaVersion( "Java 1.2", 120 );
   public static final JavaVersion  JAVA1_3  = new JavaVersion( "Java 1.3", 130 );

   private JavaVersion( final String name, final int value )
   {
     super( name, value );
   }
 }
 

The above class could then be used as follows:

 import org.apache.avalon.framework.context.Context;
 import org.apache.avalon.framework.context.Contextualizable;
 import org.apache.avalon.framework.context.ContextException;

 public class MyComponent implements Contextualizable
 {
   JavaVersion requiredVer = JavaVersion.JAVA1_2;

   public void contextualize(Context context)
       throws ContextException
   {
     JavaVersion ver = (JavaVersion)context.get("java.version");
     if ( ver.isLessThan( requiredVer ) )
     {
       throw new RuntimeException( requiredVer.getName()+" or higher required" );
     }
   }
 }
 

As with Enum, the ValuedEnum(String, int, Map) constructor can be used to populate a Map, from which further functionality can be derived.

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: ValuedEnum.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 int	m_value	The value contained in enum.

Constructor Summary

Constructors

Modifier	Constructor	Description
protected	ValuedEnum(java.lang.String name, int value)	Constructor for enum item.
protected	ValuedEnum(java.lang.String name, int value, java.util.Map map)	Constructor for enum item so that it gets added to Map at creation.

Method Summary

Modifier and Type	Method	Description
boolean	equals(java.lang.Object o)	Tests for equality.
int	getValue()	Get value of enum item.
int	hashCode()
boolean	isEqualTo(ValuedEnum other)	Test if enum item is equal in value to other enum.
boolean	isGreaterThan(ValuedEnum other)	Test if enum item is greater than in value to other enum.
boolean	isGreaterThanOrEqual(ValuedEnum other)	Test if enum item is greater than or equal in value to other enum.
boolean	isLessThan(ValuedEnum other)	Test if enum item is less than in value to other enum.
boolean	isLessThanOrEqual(ValuedEnum other)	Test if enum item is less than or equal in value to other enum.
java.lang.String	toString()	Override toString method to produce human readable description.

Methods inherited from class org.apache.avalon.framework.Enum

getName

Methods inherited from class java.lang.Object

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

Field Detail

m_value

private final int m_value

The value contained in enum.

Constructor Detail

ValuedEnum

protected ValuedEnum(java.lang.String name,
                     int value)

Constructor for enum item.

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

Parameters:

name - the name of enum item.

value - the value of enum item.

ValuedEnum

protected ValuedEnum(java.lang.String name,
                     int value,
                     java.util.Map map)

Constructor for enum item so that it gets added to Map at creation. Adding to a map is useful for implementing find...() style methods.

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

Parameters:

name - the name of enum item.

value - the value of enum item.

map - the Map to add enum item to.

Method Detail

getValue

public final int getValue()

Get value of enum item.

Returns:

the enum item's value.

isEqualTo

public final boolean isEqualTo(ValuedEnum other)

Test if enum item is equal in value to other enum.

Parameters:

other - the other enum

Returns:

true if equal

isGreaterThan

public final boolean isGreaterThan(ValuedEnum other)

Test if enum item is greater than in value to other enum.

Parameters:

other - the other enum

Returns:

true if greater than

isGreaterThanOrEqual

public final boolean isGreaterThanOrEqual(ValuedEnum other)

Test if enum item is greater than or equal in value to other enum.

Parameters:

other - the other enum

Returns:

true if greater than or equal

isLessThan

public final boolean isLessThan(ValuedEnum other)

Test if enum item is less than in value to other enum.

Parameters:

other - the other enum

Returns:

true if less than

isLessThanOrEqual

public final boolean isLessThanOrEqual(ValuedEnum other)

Test if enum item is less than or equal in value to other enum.

Parameters:

other - the other enum

Returns:

true if less than or equal

equals

public boolean equals(java.lang.Object o)

Tests for equality. Two Enum:s are considered equal if they are of the same class, have the same name, and same value.

Overrides:

equals in class Enum

Parameters:

o - the other object

Returns:

the equality status

hashCode

public int hashCode()

Overrides:

hashCode in class Enum

toString

public java.lang.String toString()

Override toString method to produce human readable description.

Overrides:

toString in class Enum

Returns:

String in the form type[name=value], eg.: JavaVersion[Java 1.0=100].