java.lang.Object
java.lang.Enum<E>
- Type Parameters:
E- The type of the enum subclass
- All Implemented Interfaces:
Serializable,Comparable<E>,Constable
public abstract classEnum<E extends Enum<E>>extendsObjectimplementsConstable,Comparable<E>,Serializable
This is the common base class of all Java language enumeration classes. More information about enums, including descriptions of the implicitly declared methods synthesized by the compiler, can be found in section8.9 ofThe Java Language Specification. Enumeration classes are all serializable and receive special handling by the serialization mechanism. The serialized representation used for enum constants cannot be customized. Declarations of methods and fields that would otherwise interact with serialization are ignored, including
serialVersionUID; see theJava Object Serialization Specification for details.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 efficientset andmap implementations are available.
- SeeJava Language Specification:
- 8.9 Enum Classes
8.9.3 Enum Members - Since:
- 1.5
- External Specifications
- See Also:
Nested Class Summary
Nested ClassesModifier and TypeClassDescriptionstatic final classEnum.EnumDesc<E extendsEnum<E>>Anominal descriptor for anenumconstant.Constructor Summary
ConstructorsMethod Summary
Modifier and TypeMethodDescriptionprotected finalObjectclone()Throws CloneNotSupportedException.final intCompares this enum with the specified object for order.finalOptional<Enum.EnumDesc<E>> Returns an enum descriptorEnumDescfor this instance, if one can be constructed, or an emptyOptionalif one cannot be.final booleanReturns true if the specified object is equal to this enum constant.protected final voidfinalize()Deprecated, for removal: This API element is subject to removal in a future version.Finalization has been deprecated for removal.Returns the Class object corresponding to this enum constant's enum type.final inthashCode()Returns a hash code for this enum constant.finalStringname()Returns the name of this enum constant, exactly as declared in its enum declaration.final intordinal()Returns the ordinal of this enumeration constant (its position in its enum declaration, where the initial constant is assigned an ordinal of zero).toString()Returns the name of this enum constant, as contained in the declaration.static <T extendsEnum<T>>
TReturns the enum constant of the specified enum class with the specified name.
Constructor Details
Enum
Sole constructor. Programmers cannot invoke this constructor. It is for use by code emitted by the compiler in response to enum class 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 Details
name
Returns the name of this enum constant, exactly as declared in its enum declaration.Most programmers should use thetoString()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 asEnumSetandEnumMap.- Returns:
- the ordinal of this enumeration constant
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 class should override this method when a more "programmer-friendly" string form exists.equals
hashCode
clone
Throws CloneNotSupportedException. This guarantees that enums are never cloned, which is necessary to preserve their "singleton" status.- Overrides:
clonein classObject- Returns:
- (never returns)
- Throws:
CloneNotSupportedException- if the object's class does not support theCloneableinterface. Subclasses that override theclonemethod can also throw this exception to indicate that an instance cannot be cloned.- See Also:
compareTo
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:
compareToin interfaceComparable<E extendsEnum<E>>- Parameters:
o- the object to be compared.- Returns:
- a negative integer, zero, or a positive integer as this object is less than, equal to, or greater than the specified object.
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 theObject.getClass()method for enum constants with constant-specific class bodies.)- Returns:
- the Class object corresponding to this enum constant's enum type
describeConstable
Returns an enum descriptorEnumDescfor this instance, if one can be constructed, or an emptyOptionalif one cannot be.- Specified by:
describeConstablein interfaceConstable- Returns:
- An
Optionalcontaining the resulting nominal descriptor, or an emptyOptionalif one cannot be constructed. - Since:
- 12
valueOf
Returns the enum constant of the specified enum class with the specified name. The name must match exactly an identifier used to declare an enum constant in this class. (Extraneous whitespace characters are not permitted.)Note that for a particular enum class
T, the implicitly declaredpublic static T valueOf(String)method on that enum may be used instead of this method to map from a name to the corresponding enum constant. All the constants of an enum class can be obtained by calling the implicitpublic static T[] values()method of that class.- Type Parameters:
T- The enum class whose constant is to be returned- Parameters:
enumClass- theClassobject of the enum class from which to return a constantname- the name of the constant to return- Returns:
- the enum constant of the specified enum class with the specified name
- Throws:
IllegalArgumentException- if the specified enum class has no constant with the specified name, or the specified class object does not represent an enum classNullPointerException- ifenumClassornameis null- Since:
- 1.5
finalize
Deprecated, for removal: This API element is subject to removal in a future version.Finalization has been deprecated for removal. SeeObject.finalize()for background information and details about migration options.enum classes cannot have finalize methods.