eu.simuline.util

Class SoftEnum<E extends SoftEnum<E>>

java.lang.Object

eu.simuline.util.SoftEnum<E>

Type Parameters:

E - The enum type subclass

All Implemented Interfaces:

Serializable, Comparable<E>

public abstract class SoftEnum<E extends SoftEnum<E>>
extends Object
implements Comparable<E>, Serializable

This class is inspired by Enum and is intended as common base class of classes we shall call 'soft enums'. While soft enums are ordinary classes and lack all support special to enumeration types, they are also not subject to the restrictions that come with them.

It is the programmer who is responsible for implementing soft enums in a proper way.

As enumeration types are implicitely final subclasses of Enum, 'soft enums' are derived from SoftEnum and shall be final except if constants overwrite methods. A 'soft enum' shall have no instances other than those defined by its enum constants. More information about enums, including descriptions of the implicitly declared methods synthesized by the compiler, can be found in section 8.9 of The Java™ Language Specification.

Note that when using an enumeration type as the type of a set or as the type of the keys in a map, specialized and efficient set and map implementations are available.

Since:

1.5

Author:

Josh Bloch, Neal Gafter

See Also:

Class.getEnumConstants(), EnumSet, EnumMap, Serialized Form

Field Summary

Fields

Modifier and Type	Field and Description
private String	name The name of this enum constant, as declared in the enum declaration.
private int	ordinal The ordinal of this enumeration constant (its position in the enum declaration, where the initial constant is assigned an ordinal of zero).
private static long	serialVersionUID

Constructor Summary

Constructors

Modifier	Constructor and Description
protected	SoftEnum(String name, int ordinal) Sole constructor.

Method Summary

Modifier and Type	Method and Description
SoftEnum<E>	clone() Throws CloneNotSupportedException.
int	compareTo(E obj) Compares this enum with the specified object for order.
boolean	equals(Object other) Returns true if the specified object is equal to this enum constant.
protected void	finalize() enum classes cannot have finalize methods.
Class<?>	getDeclaringClass() Returns the Class object corresponding to this enum constant's enum type.
int	hashCode() Returns a hash code for this enum constant.
String	name() Returns the name of this enum constant, exactly as declared in its enum declaration.
int	ordinal() Returns the ordinal of this enumeration constant (its position in its enum declaration, where the initial constant is assigned an ordinal of zero).
private void	readObject(ObjectInputStream stream) Prevent default deserialization.
private void	readObjectNoData()
String	toString() Returns the name of this enum constant, as contained in the declaration.

Methods inherited from class java.lang.Object

getClass, notify, notifyAll, wait, wait, wait

Field Detail

serialVersionUID

private static final long serialVersionUID

See Also:

Constant Field Values

name

private final String name

The name of this enum constant, as declared in the enum declaration. Most programmers should use the toString() method rather than accessing this field.

ordinal

private final int ordinal

The ordinal of this enumeration constant (its position in the enum declaration, where the initial constant is assigned an ordinal of zero). Most programmers will have no use for this field. It is designed for use by sophisticated enum-based data structures, such as EnumSet and EnumMap.

Constructor Detail

SoftEnum

protected SoftEnum(String name,
                   int ordinal)

Sole constructor. Programmers cannot invoke this constructor. It is for use by code emitted by the compiler in response to enum type declarations.

Parameters:

name - - The name of this enum constant, which is the identifier used to declare it.

ordinal - - The ordinal of this enumeration constant (its position in the enum declaration, where the initial constant is assigned an ordinal of zero).

Method Detail

name

public final String name()

Returns the name of this enum constant, exactly as declared in its enum declaration. Most programmers should use the toString() method in preference to this one, as the toString method may return a more user-friendly name. This method is designed primarily for use in specialized situations where correctness depends on getting the exact name, which will not vary from release to release.

Returns:

the name of this enum constant

ordinal

public final int ordinal()

Returns the ordinal of this enumeration constant (its position in its enum declaration, where the initial constant is assigned an ordinal of zero). Most programmers will have no use for this method. It is designed for use by sophisticated enum-based data structures, such as EnumSet and EnumMap.

Returns:

the ordinal of this enumeration constant

toString

public final String toString()

Returns the name of this enum constant, as contained in the declaration. This method may be overridden, though it typically isn't necessary or desirable. An enum type should override this method when a more "programmer-friendly" string form exists.

Overrides:

toString in class Object

Returns:

the name of this enum constant

equals

public final boolean equals(Object other)

Returns true if the specified object is equal to this enum constant.

Overrides:

equals in class Object

Parameters:

other - the object to be compared for equality with this object.

Returns:

true if the specified object is equal to this enum constant.

hashCode

public final int hashCode()

Returns a hash code for this enum constant.

Overrides:

hashCode in class Object

Returns:

a hash code for this enum constant.

clone

public final SoftEnum<E> clone()
                        throws CloneNotSupportedException

Throws CloneNotSupportedException. This guarantees that enums are never cloned, which is necessary to preserve their "singleton" status.

Overrides:

clone in class Object

Returns:

(never returns)

Throws:

CloneNotSupportedException

compareTo

public final int compareTo(E obj)

Compares this enum with the specified object for order. Returns a negative integer, zero, or a positive integer as this object is less than, equal to, or greater than the specified object. Enum constants are only comparable to other enum constants of the same enum type. The natural order implemented by this method is the order in which the constants are declared.

Specified by:

compareTo in interface Comparable<E extends SoftEnum<E>>

getDeclaringClass

public final Class<?> getDeclaringClass()

Returns the Class object corresponding to this enum constant's enum type. Two enum constants e1 and e2 are of the same enum type if and only if e1.getDeclaringClass() == e2.getDeclaringClass(). (The value returned by this method may differ from the one returned by the Object.getClass() method for enum constants with constant-specific class bodies.)

Returns:

the Class object corresponding to this enum constant's enum type

finalize

protected final void finalize()

enum classes cannot have finalize methods.

Overrides:

finalize in class Object

readObject

private void readObject(ObjectInputStream stream)
                 throws IOException,
                        ClassNotFoundException

Prevent default deserialization.

Throws:

IOException

ClassNotFoundException

readObjectNoData

private void readObjectNoData()
                       throws ObjectStreamException

Throws:

ObjectStreamException