org.apache.avalon.framework

Class 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 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
intm_value
The value contained in enum.
Constructor Summary
protected ValuedEnum(String name, int value)
Constructor for enum item.
protected ValuedEnum(String name, int value, Map map)
Constructor for enum item so that it gets added to Map at creation.
Method Summary
booleanequals(Object o)
Tests for equality.
intgetValue()
Get value of enum item.
inthashCode()
booleanisEqualTo(ValuedEnum other)
Test if enum item is equal in value to other enum.
booleanisGreaterThan(ValuedEnum other)
Test if enum item is greater than in value to other enum.
booleanisGreaterThanOrEqual(ValuedEnum other)
Test if enum item is greater than or equal in value to other enum.
booleanisLessThan(ValuedEnum other)
Test if enum item is less than in value to other enum.
booleanisLessThanOrEqual(ValuedEnum other)
Test if enum item is less than or equal in value to other enum.
StringtoString()
Override toString method to produce human readable description.

Field Detail

m_value

private final int m_value
The value contained in enum.

Constructor Detail

ValuedEnum

protected ValuedEnum(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(String name, int value, 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

equals

public boolean equals(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.

Parameters: o the other object

Returns: the equality status

getValue

public final int getValue()
Get value of enum item.

Returns: the enum item's value.

hashCode

public int hashCode()

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

toString

public String toString()
Override toString method to produce human readable description.

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