OpenJDK 1.22 · java.util.EnumSet · APIdia, the JavaDoc alternative

A specialized Set implementation for use with enum types. All of the elements in an enum set must come from a single enum type that is specified, explicitly or implicitly, when the set is created. Enum sets are represented internally as bit vectors. This representation is extremely compact and efficient. The space and time performance of this class should be good enough to allow its use as a high-quality, typesafe alternative to traditional int-based "bit flags." Even bulk operations (such as containsAll and retainAll) should run very quickly if their argument is also an enum set.

The iterator returned by the iterator method traverses the elements in their natural order (the order in which the enum constants are declared). The returned iterator is weakly consistent: it will never throw ConcurrentModificationException and it may or may not show the effects of any modifications to the set that occur while the iteration is in progress.

Null elements are not permitted. Attempts to insert a null element will throw NullPointerException. Attempts to test for the presence of a null element or to remove one will, however, function properly.

Like most collection implementations, EnumSet is not synchronized. If multiple threads access an enum set concurrently, and at least one of the threads modifies the set, it should be synchronized externally. This is typically accomplished by synchronizing on some object that naturally encapsulates the enum set. If no such object exists, the set should be "wrapped" using the Collections#synchronizedSet method. This is best done at creation time, to prevent accidental unsynchronized access:

Set<MyEnum> s = Collections.synchronizedSet(EnumSet.noneOf(MyEnum.class));

Implementation Note

All basic operations execute in constant time. They are likely (though not guaranteed) to be much faster than their HashSet counterparts. Even bulk operations execute in constant time if their argument is also an enum set.

This class is a member of the Java Collections Framework.

Nested and Inner Type Summary

Modifier and Type	Class and Description
private static class	EnumSet.SerializationProxy<E extends Enum<E>> This class is used to serialize all EnumSet instances, regardless of implementation type.

Field Summary

Modifier and Type	Field and Description
pack-priv final transient Class<E>	elementType The class of all the elements of this set.
private static final long	serialVersionUID
pack-priv final transient Enum<?>[]	universe All of the values comprising E.

Constructor Summary

Access	Constructor and Description
pack-priv	EnumSet(Class<E> elementType, Enum<?>[] universe)

Method Summary

Modifier and Type	Method and Description
pack-priv abstract void	addAll() Adds all of the elements from the appropriate enum type to this enum set, which is empty prior to the call.
pack-priv abstract void	addRange(E from, E to) Adds the specified range to this enum set, which is empty prior to the call.
public static < The class of the elements in the set E extends Enum<E>> EnumSet<E>	Returns: An enum set containing all the elements in the specified type. allOf(Class<E> the class object of the element type for this enum set elementType) Creates an enum set containing all of the elements in the specified element type.
public EnumSet<E>	Returns: a copy of this set clone() Overrides java.lang.Object.clone. Returns a copy of this set.
pack-priv abstract void	complement() Complements the contents of this enum set.
public static < The class of the elements in the enum set E extends Enum<E>> EnumSet<E>	Returns: The complement of the specified set in this set complementOf(EnumSet<E> the enum set from whose complement to initialize this enum set s) Creates an enum set with the same element type as the specified enum set, initially containing all the elements of this type that are not contained in the specified set.
public static < The class of the elements in the set E extends Enum<E>> EnumSet<E>	Returns: A copy of the specified enum set. copyOf(EnumSet<E> the enum set from which to initialize this enum set s) Creates an enum set with the same element type as the specified enum set, initially containing the same elements (if any).
public static < The class of the elements in the collection E extends Enum<E>> EnumSet<E>	Returns: An enum set initialized from the given collection. copyOf(Collection<E> the collection from which to initialize this enum set c) Hides java.util.Set.copyOf. Creates an enum set initialized from the specified collection.
private static <E extends Enum<E>> E[]	getUniverse(Class<E> elementType) Returns all of the values comprising E.
public static < The class of the elements in the set E extends Enum<E>> EnumSet<E>	Returns: An empty enum set of the specified type. noneOf(Class<E> the class object of the element type for this enum set elementType) Creates an empty enum set with the specified element type.
public static < The class of the specified element and of the set E extends Enum<E>> EnumSet<E>	Returns: an enum set initially containing the specified element of(E the element that this set is to contain initially e) Hides java.util.Set.of. Creates an enum set initially containing the specified element.
public static < The class of the parameter elements and of the set E extends Enum<E>> EnumSet<E>	Returns: an enum set initially containing the specified elements of(E an element that this set is to contain initially e1, E another element that this set is to contain initially e2) Hides java.util.Set.of. Creates an enum set initially containing the specified elements.
public static < The class of the parameter elements and of the set E extends Enum<E>> EnumSet<E>	Returns: an enum set initially containing the specified elements of(E an element that this set is to contain initially e1, E another element that this set is to contain initially e2, E another element that this set is to contain initially e3) Hides java.util.Set.of. Creates an enum set initially containing the specified elements.
public static < The class of the parameter elements and of the set E extends Enum<E>> EnumSet<E>	Returns: an enum set initially containing the specified elements of(E an element that this set is to contain initially e1, E another element that this set is to contain initially e2, E another element that this set is to contain initially e3, E another element that this set is to contain initially e4) Hides java.util.Set.of. Creates an enum set initially containing the specified elements.
public static < The class of the parameter elements and of the set E extends Enum<E>> EnumSet<E>	Returns: an enum set initially containing the specified elements of(E an element that this set is to contain initially e1, E another element that this set is to contain initially e2, E another element that this set is to contain initially e3, E another element that this set is to contain initially e4, E another element that this set is to contain initially e5) Hides java.util.Set.of. Creates an enum set initially containing the specified elements.
public static < The class of the parameter elements and of the set E extends Enum<E>> EnumSet<E>	Returns: an enum set initially containing the specified elements of(E an element that the set is to contain initially first, E... the remaining elements the set is to contain initially rest) Hides java.util.Set.of. Creates an enum set initially containing the specified elements.
public static < The class of the parameter elements and of the set E extends Enum<E>> EnumSet<E>	Returns: an enum set initially containing all of the elements in the range defined by the two specified endpoints range(E the first element in the range from, E the last element in the range to) Creates an enum set initially containing all of the elements in the range defined by the two specified endpoints.
private void	readObject(ObjectInputStream the stream s) Throws `InvalidObjectException`.
private void	readObjectNoData() Throws `InvalidObjectException`.
pack-priv final void	typeCheck(E e) Throws an exception if e is not of the correct type for this enum set.
pack-priv Object	Returns: a `SerializationProxy` representing the state of this instance writeReplace() Returns a SerializationProxy representing the state of this instance.

Inherited from java.util.AbstractSet:: equals hashCode removeAll

Field Detail

elementType	back to summary
pack-priv final transient Class<E> elementType The class of all the elements of this set.

serialVersionUID	back to summary
private static final long serialVersionUID Annotations @Serial

universe	back to summary
pack-priv final transient Enum<?>[] universe All of the values comprising E. (Cached for performance.)

Constructor Detail

EnumSet	back to summary
pack-priv EnumSet(Class<E> elementType, Enum<?>[] universe)

Method Detail

addAll	back to summary
pack-priv abstract void addAll() Adds all of the elements from the appropriate enum type to this enum set, which is empty prior to the call.

addRange	back to summary
pack-priv abstract void addRange(E from, E to) Adds the specified range to this enum set, which is empty prior to the call.

allOf back to summary

allOf	back to summary
public static <E extends Enum<E>> EnumSet<E> allOf(Class<E> elementType) Creates an enum set containing all of the elements in the specified element type. Parameters <E> The class of the elements in the set elementType:Class<E> the class object of the element type for this enum set Returns:EnumSet<E> An enum set containing all the elements in the specified type. Exceptions NullPointerException: if `elementType` is null

public static <E extends Enum<E>> EnumSet<E> allOf(Class<E> elementType)

Creates an enum set containing all of the elements in the specified element type.

Parameters

<E>: The class of the elements in the set
elementType:Class<E>: the class object of the element type for this enum set

Returns:EnumSet<E>

An enum set containing all the elements in the specified type.

Exceptions

NullPointerException:: if elementType is null

clone	back to summary
public EnumSet<E> clone() Overrides java.lang.Object.clone. Returns a copy of this set. Returns:EnumSet<E> a copy of this set Annotations @SuppressWarnings:unchecked

clone

back to summary

public EnumSet<E> clone()

Overrides java.lang.Object.clone.

Returns a copy of this set.

Returns:EnumSet<E>

a copy of this set

Annotations

@SuppressWarnings:unchecked

complement	back to summary
pack-priv abstract void complement() Complements the contents of this enum set.

complementOf back to summary

complementOf	back to summary
public static <E extends Enum<E>> EnumSet<E> complementOf(EnumSet<E> s) Creates an enum set with the same element type as the specified enum set, initially containing all the elements of this type that are not contained in the specified set. Parameters <E> The class of the elements in the enum set s:EnumSet<E> the enum set from whose complement to initialize this enum set Returns:EnumSet<E> The complement of the specified set in this set Exceptions NullPointerException: if `s` is null

public static <E extends Enum<E>> EnumSet<E> complementOf(EnumSet<E> s)

Creates an enum set with the same element type as the specified enum set, initially containing all the elements of this type that are not contained in the specified set.

Parameters

<E>: The class of the elements in the enum set
s:EnumSet<E>: the enum set from whose complement to initialize this enum set

Returns:EnumSet<E>

The complement of the specified set in this set

Exceptions

NullPointerException:: if s is null

copyOf back to summary

copyOf	back to summary
public static <E extends Enum<E>> EnumSet<E> copyOf(EnumSet<E> s) Creates an enum set with the same element type as the specified enum set, initially containing the same elements (if any). Parameters <E> The class of the elements in the set s:EnumSet<E> the enum set from which to initialize this enum set Returns:EnumSet<E> A copy of the specified enum set. Exceptions NullPointerException: if `s` is null

public static <E extends Enum<E>> EnumSet<E> copyOf(EnumSet<E> s)

Creates an enum set with the same element type as the specified enum set, initially containing the same elements (if any).

Parameters

<E>: The class of the elements in the set
s:EnumSet<E>: the enum set from which to initialize this enum set

Returns:EnumSet<E>

A copy of the specified enum set.

Exceptions

NullPointerException:: if s is null

copyOf back to summary

copyOf	back to summary
public static <E extends Enum<E>> EnumSet<E> copyOf(Collection<E> c) Hides java.util.Set.copyOf. Creates an enum set initialized from the specified collection. If the specified collection is an `EnumSet` instance, this static factory method behaves identically to `copyOf(EnumSet)`. Otherwise, the specified collection must contain at least one element (in order to determine the new enum set's element type). Parameters <E> The class of the elements in the collection c:Collection<E> the collection from which to initialize this enum set Returns:EnumSet<E> An enum set initialized from the given collection. Exceptions IllegalArgumentException: if `c` is not an `EnumSet` instance and contains no elements NullPointerException: if `c` is null

public static <E extends Enum<E>> EnumSet<E> copyOf(Collection<E> c)

Hides java.util.Set.copyOf.

Creates an enum set initialized from the specified collection. If the specified collection is an EnumSet instance, this static factory method behaves identically to copyOf(EnumSet). Otherwise, the specified collection must contain at least one element (in order to determine the new enum set's element type).

Parameters

<E>: The class of the elements in the collection
c:Collection<E>: the collection from which to initialize this enum set

Returns:EnumSet<E>

An enum set initialized from the given collection.

Exceptions

IllegalArgumentException:: if c is not an EnumSet instance and contains no elements
NullPointerException:: if c is null

getUniverse	back to summary
private static <E extends Enum<E>> E[] getUniverse(Class<E> elementType) Returns all of the values comprising E. The result is uncloned, cached, and shared by all callers.

noneOf back to summary

noneOf	back to summary
public static <E extends Enum<E>> EnumSet<E> noneOf(Class<E> elementType) Creates an empty enum set with the specified element type. Parameters <E> The class of the elements in the set elementType:Class<E> the class object of the element type for this enum set Returns:EnumSet<E> An empty enum set of the specified type. Exceptions NullPointerException: if `elementType` is null

public static <E extends Enum<E>> EnumSet<E> noneOf(Class<E> elementType)

Creates an empty enum set with the specified element type.

Parameters

<E>: The class of the elements in the set
elementType:Class<E>: the class object of the element type for this enum set

Returns:EnumSet<E>

An empty enum set of the specified type.

Exceptions

NullPointerException:: if elementType is null

of back to summary

of	back to summary
public static <E extends Enum<E>> EnumSet<E> of(E e) Hides java.util.Set.of. Creates an enum set initially containing the specified element. Overloadings of this method exist to initialize an enum set with one through five elements. A sixth overloading is provided that uses the varargs feature. This overloading may be used to create an enum set initially containing an arbitrary number of elements, but is likely to run slower than the overloadings that do not use varargs. Parameters <E> The class of the specified element and of the set e:E the element that this set is to contain initially Returns:EnumSet<E> an enum set initially containing the specified element Exceptions NullPointerException: if `e` is null

public static <E extends Enum<E>> EnumSet<E> of(E e)

Hides java.util.Set.of.

Creates an enum set initially containing the specified element. Overloadings of this method exist to initialize an enum set with one through five elements. A sixth overloading is provided that uses the varargs feature. This overloading may be used to create an enum set initially containing an arbitrary number of elements, but is likely to run slower than the overloadings that do not use varargs.

Parameters

<E>: The class of the specified element and of the set
e:E: the element that this set is to contain initially

Returns:EnumSet<E>

an enum set initially containing the specified element

Exceptions

NullPointerException:: if e is null

of	back to summary
public static <E extends Enum<E>> EnumSet<E> of(E e1, E e2) Hides java.util.Set.of. Creates an enum set initially containing the specified elements. Overloadings of this method exist to initialize an enum set with one through five elements. A sixth overloading is provided that uses the varargs feature. This overloading may be used to create an enum set initially containing an arbitrary number of elements, but is likely to run slower than the overloadings that do not use varargs. Parameters <E> The class of the parameter elements and of the set e1:E an element that this set is to contain initially e2:E another element that this set is to contain initially Returns:EnumSet<E> an enum set initially containing the specified elements Exceptions NullPointerException: if any parameters are null

back to summary

public static <E extends Enum<E>> EnumSet<E> of(E e1, E e2)

Hides java.util.Set.of.

Creates an enum set initially containing the specified elements. Overloadings of this method exist to initialize an enum set with one through five elements. A sixth overloading is provided that uses the varargs feature. This overloading may be used to create an enum set initially containing an arbitrary number of elements, but is likely to run slower than the overloadings that do not use varargs.

Parameters

<E>: The class of the parameter elements and of the set
e1:E: an element that this set is to contain initially
e2:E: another element that this set is to contain initially

Returns:EnumSet<E>

an enum set initially containing the specified elements

Exceptions

NullPointerException:: if any parameters are null

of	back to summary
public static <E extends Enum<E>> EnumSet<E> of(E e1, E e2, E e3) Hides java.util.Set.of. Creates an enum set initially containing the specified elements. Overloadings of this method exist to initialize an enum set with one through five elements. A sixth overloading is provided that uses the varargs feature. This overloading may be used to create an enum set initially containing an arbitrary number of elements, but is likely to run slower than the overloadings that do not use varargs. Parameters <E> The class of the parameter elements and of the set e1:E an element that this set is to contain initially e2:E another element that this set is to contain initially e3:E another element that this set is to contain initially Returns:EnumSet<E> an enum set initially containing the specified elements Exceptions NullPointerException: if any parameters are null

back to summary

public static <E extends Enum<E>> EnumSet<E> of(E e1, E e2, E e3)

Hides java.util.Set.of.

Parameters

<E>: The class of the parameter elements and of the set
e1:E: an element that this set is to contain initially
e2:E: another element that this set is to contain initially
e3:E: another element that this set is to contain initially

Returns:EnumSet<E>

an enum set initially containing the specified elements

Exceptions

NullPointerException:: if any parameters are null

of	back to summary
public static <E extends Enum<E>> EnumSet<E> of(E e1, E e2, E e3, E e4) Hides java.util.Set.of. Creates an enum set initially containing the specified elements. Overloadings of this method exist to initialize an enum set with one through five elements. A sixth overloading is provided that uses the varargs feature. This overloading may be used to create an enum set initially containing an arbitrary number of elements, but is likely to run slower than the overloadings that do not use varargs. Parameters <E> The class of the parameter elements and of the set e1:E an element that this set is to contain initially e2:E another element that this set is to contain initially e3:E another element that this set is to contain initially e4:E another element that this set is to contain initially Returns:EnumSet<E> an enum set initially containing the specified elements Exceptions NullPointerException: if any parameters are null

back to summary

public static <E extends Enum<E>> EnumSet<E> of(E e1, E e2, E e3, E e4)

Hides java.util.Set.of.

Parameters

<E>: The class of the parameter elements and of the set
e1:E: an element that this set is to contain initially
e2:E: another element that this set is to contain initially
e3:E: another element that this set is to contain initially
e4:E: another element that this set is to contain initially

Returns:EnumSet<E>

an enum set initially containing the specified elements

Exceptions

NullPointerException:: if any parameters are null

of	back to summary
public static <E extends Enum<E>> EnumSet<E> of(E e1, E e2, E e3, E e4, E e5) Hides java.util.Set.of. Creates an enum set initially containing the specified elements. Overloadings of this method exist to initialize an enum set with one through five elements. A sixth overloading is provided that uses the varargs feature. This overloading may be used to create an enum set initially containing an arbitrary number of elements, but is likely to run slower than the overloadings that do not use varargs. Parameters <E> The class of the parameter elements and of the set e1:E an element that this set is to contain initially e2:E another element that this set is to contain initially e3:E another element that this set is to contain initially e4:E another element that this set is to contain initially e5:E another element that this set is to contain initially Returns:EnumSet<E> an enum set initially containing the specified elements Exceptions NullPointerException: if any parameters are null

back to summary

public static <E extends Enum<E>> EnumSet<E> of(E e1, E e2, E e3, E e4, E e5)

Hides java.util.Set.of.

Parameters

<E>: The class of the parameter elements and of the set
e1:E: an element that this set is to contain initially
e2:E: another element that this set is to contain initially
e3:E: another element that this set is to contain initially
e4:E: another element that this set is to contain initially
e5:E: another element that this set is to contain initially

Returns:EnumSet<E>

an enum set initially containing the specified elements

Exceptions

NullPointerException:: if any parameters are null

of back to summary

of	back to summary
public static <E extends Enum<E>> EnumSet<E> of(E first, E... rest) Hides java.util.Set.of. Creates an enum set initially containing the specified elements. This factory, whose parameter list uses the varargs feature, may be used to create an enum set initially containing an arbitrary number of elements, but it is likely to run slower than the overloadings that do not use varargs. Parameters <E> The class of the parameter elements and of the set first:E an element that the set is to contain initially rest:E[] the remaining elements the set is to contain initially Returns:EnumSet<E> an enum set initially containing the specified elements Annotations @SafeVarargs Exceptions NullPointerException: if any of the specified elements are null, or if `rest` is null

public static <E extends Enum<E>> EnumSet<E> of(E first, E... rest)

Hides java.util.Set.of.

Creates an enum set initially containing the specified elements. This factory, whose parameter list uses the varargs feature, may be used to create an enum set initially containing an arbitrary number of elements, but it is likely to run slower than the overloadings that do not use varargs.

Parameters

<E>: The class of the parameter elements and of the set
first:E: an element that the set is to contain initially
rest:E[]: the remaining elements the set is to contain initially

Returns:EnumSet<E>

an enum set initially containing the specified elements

Annotations

@SafeVarargs

Exceptions

NullPointerException:: if any of the specified elements are null, or if rest is null

range back to summary

range	back to summary
public static <E extends Enum<E>> EnumSet<E> range(E from, E to) Creates an enum set initially containing all of the elements in the range defined by the two specified endpoints. The returned set will contain the endpoints themselves, which may be identical but must not be out of order. Parameters <E> The class of the parameter elements and of the set from:E the first element in the range to:E the last element in the range Returns:EnumSet<E> an enum set initially containing all of the elements in the range defined by the two specified endpoints Exceptions NullPointerException: if `from` or `to` are null IllegalArgumentException: if `from.compareTo(to) > 0`

public static <E extends Enum<E>> EnumSet<E> range(E from, E to)

Creates an enum set initially containing all of the elements in the range defined by the two specified endpoints. The returned set will contain the endpoints themselves, which may be identical but must not be out of order.

Parameters

<E>: The class of the parameter elements and of the set
from:E: the first element in the range
to:E: the last element in the range

Returns:EnumSet<E>

an enum set initially containing all of the elements in the range defined by the two specified endpoints

Exceptions

NullPointerException:: if from or to are null
IllegalArgumentException:: if from.compareTo(to) > 0

readObject back to summary

readObject	back to summary
private void readObject(ObjectInputStream s) throws InvalidObjectException Throws `InvalidObjectException`. Parameters s:ObjectInputStream the stream Annotations @Serial Exceptions InvalidObjectException: always

private void readObject(ObjectInputStream s) throws InvalidObjectException

Throws InvalidObjectException.

Parameters

s:ObjectInputStream: the stream

Annotations

@Serial

Exceptions

InvalidObjectException:: always

readObjectNoData back to summary

readObjectNoData	back to summary
private void readObjectNoData() throws InvalidObjectException Throws `InvalidObjectException`. Annotations @Serial Exceptions InvalidObjectException: always

private void readObjectNoData() throws InvalidObjectException

Throws InvalidObjectException.

Annotations

@Serial

Exceptions

InvalidObjectException:: always

typeCheck	back to summary
pack-priv final void typeCheck(E e) Throws an exception if e is not of the correct type for this enum set.

writeReplace back to summary

writeReplace	back to summary
pack-priv Object writeReplace() Returns a SerializationProxy representing the state of this instance. Returns:Object a `SerializationProxy` representing the state of this instance Annotations @Serial

pack-priv Object writeReplace()

Returns a SerializationProxy representing the state of this instance.

Returns:Object

a SerializationProxy representing the state of this instance

Annotations

@Serial

Modifier and Type	Field and Description
private final Enum<?>[]	elements The elements contained in this enum set.
private final Class<E>	elementType The element type of this enum set.
private static final long	serialVersionUID
private static final Enum<?>[]	ZERO_LENGTH_ENUM_ARRAY

public abstract sealed Class EnumSet<E extends Enum<E>>

Nested and Inner Type Summary

Field Summary

Constructor Summary

Method Summary

Field Detail

Constructor Detail

Method Detail

private Class EnumSet.SerializationProxy<E extends Enum<E>>

Field Summary

Constructor Summary

Method Summary

Field Detail

Constructor Detail

Method Detail