程序包 java.lang

类 Enum<E extends Enum<E>>

java.lang.Object

java.lang.Enum<E>

类型参数:

E - The enum type subclass

所有已实现的接口:

Serializable, Comparable<E>

public 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.

从以下版本开始:

1.5

另请参阅:

Class.getEnumConstants(), EnumSet, EnumMap, 序列化表格

构造器概要

构造器

限定符	构造器	说明
protected	Enum(String name, int ordinal)	Sole constructor.

方法概要

限定符和类型	方法	说明
protected Object	clone()	Throws CloneNotSupportedException.
int	compareTo(E o)	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<E>	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).
String	toString()	Returns the name of this enum constant, as contained in the declaration.
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.

从类继承的方法 java.lang.Object

getClass, notify, notifyAll, wait, wait, wait

构造器详细资料

Enum

protected 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.

参数:

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).

方法详细资料

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.

返回:

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.

返回:

the ordinal of this enumeration constant

toString

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.

覆盖:

toString 在类中 Object

返回:

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.

覆盖:

equals 在类中 Object

参数:

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

返回:

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

另请参阅:

Object.hashCode(), HashMap

hashCode

public final int hashCode()

Returns a hash code for this enum constant.

覆盖:

hashCode 在类中 Object

返回:

a hash code for this enum constant.

另请参阅:

Object.equals(java.lang.Object), System.identityHashCode(java.lang.Object)

clone

protected final Object clone()
                      throws CloneNotSupportedException

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

覆盖:

clone 在类中 Object

返回:

(never returns)

抛出:

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.

另请参阅:

Cloneable

compareTo

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.

指定者:

compareTo 在接口中 Comparable<E extends Enum<E>>

参数:

o - the object to be compared.

返回:

a negative integer, zero, or a positive integer as this object is less than, equal to, or greater than the specified object.

getDeclaringClass

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.)

返回:

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

valueOf

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.

类型参数:

T - The enum type whose constant is to be returned

参数:

enumType - the Class object of the enum type from which to return a constant

name - the name of the constant to return

返回:

the enum constant of the specified enum type with the specified name

抛出:

IllegalArgumentException - if the specified enum type has no constant with the specified name, or the specified class object does not represent an enum type

NullPointerException - if enumType or name is null

从以下版本开始:

1.5

finalize

protected final void finalize()

enum classes cannot have finalize methods.

覆盖:

finalize 在类中 Object

另请参阅:

WeakReference, PhantomReference