E
- The enum type subclasspublic abstract class Enum<E extends Enum<E>> extends Object implements Comparable<E>, Serializable
This is the common base class of all Java language enumeration types. 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.
Class.getEnumConstants()
, EnumSet
, EnumMap
, Serialized Formprotected Enum(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.
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).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.
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
.
public 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.
public final boolean equals(Object other)
Returns true if the specified object is equal to this enum constant.
equals
in class Object
other
- the object to be compared for equality with this object.Object.hashCode()
, HashMap
public final int hashCode()
Returns a hash code for this enum constant.
hashCode
in class Object
Object.equals(java.lang.Object)
, System.identityHashCode(java.lang.Object)
protected final Object clone() throws CloneNotSupportedException
Throws CloneNotSupportedException. This guarantees that enums are never cloned, which is necessary to preserve their "singleton" status.
clone
in class Object
CloneNotSupportedException
- if the object's class does not support the Cloneable
interface. Subclasses that override the clone
method can also throw this exception to indicate that an instance cannot be cloned.Cloneable
public final int compareTo(E o)
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.
compareTo
in interface Comparable<E extends Enum<E>>
o
- the object to be compared.public final Class<E> 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.)
public static <T extends Enum<T>> T valueOf(Class<T> enumType, String name)
Returns the enum constant of the specified enum type with the specified name. The name must match exactly an identifier used to declare an enum constant in this type. (Extraneous whitespace characters are not permitted.)
Note that for a particular enum type T
, the implicitly declared public 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 type can be obtained by calling the implicit public static T[] values()
method of that type.
T
- The enum type whose constant is to be returnedenumType
- the Class
object of the enum type from which to return a constantname
- the name of the constant to returnIllegalArgumentException
- if the specified enum type has no constant with the specified name, or the specified class object does not represent an enum typeNullPointerException
- if enumType
or name
is nullprotected final void finalize()
enum classes cannot have finalize methods.
finalize
in class Object
WeakReference
, PhantomReference
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Documentation extracted from Debian's OpenJDK Development Kit package.
Licensed under the GNU General Public License, version 2, with the Classpath Exception.
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