E
- the enum type of elements maintained by this setSerializable
, Cloneable
, Iterable<E>
, Collection<E>
, Set<E>
public abstract sealed class EnumSet<E extends Enum<E>> extends AbstractSet<E> implements Cloneable, Serializable
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(java.util.Set<T>)
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.
Modifier and Type | Method | Description |
---|---|---|
static <E extends Enum<E>> |
allOf |
Creates an enum set containing all of the elements in the specified element type. |
EnumSet |
clone() |
Returns a copy of this set. |
static <E extends Enum<E>> |
complementOf |
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. |
static <E extends Enum<E>> |
copyOf |
Creates an enum set initialized from the specified collection. |
static <E extends Enum<E>> |
copyOf |
Creates an enum set with the same element type as the specified enum set, initially containing the same elements (if any). |
static <E extends Enum<E>> |
noneOf |
Creates an empty enum set with the specified element type. |
static <E extends Enum<E>> |
of |
Creates an enum set initially containing the specified element. |
static <E extends Enum<E>> |
of |
Creates an enum set initially containing the specified elements. |
static <E extends Enum<E>> |
of |
Creates an enum set initially containing the specified elements. |
static <E extends Enum<E>> |
of |
Creates an enum set initially containing the specified elements. |
static <E extends Enum<E>> |
of |
Creates an enum set initially containing the specified elements. |
static <E extends Enum<E>> |
of |
Creates an enum set initially containing the specified elements. |
static <E extends Enum<E>> |
range |
Creates an enum set initially containing all of the elements in the range defined by the two specified endpoints. |
equals, hashCode, removeAll
add, addAll, clear, contains, containsAll, isEmpty, iterator, remove, retainAll, toArray, toArray, toString
parallelStream, removeIf, stream, toArray
public static <E extends Enum<E>> EnumSet<E> noneOf(Class<E> elementType)
E
- The class of the elements in the setelementType
- the class object of the element type for this enum setNullPointerException
- if elementType
is nullpublic static <E extends Enum<E>> EnumSet<E> allOf(Class<E> elementType)
E
- The class of the elements in the setelementType
- the class object of the element type for this enum setNullPointerException
- if elementType
is nullpublic static <E extends Enum<E>> EnumSet<E> copyOf(EnumSet<E> s)
E
- The class of the elements in the sets
- the enum set from which to initialize this enum setNullPointerException
- if s
is nullpublic static <E extends Enum<E>> EnumSet<E> copyOf(Collection<E> c)
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).E
- The class of the elements in the collectionc
- the collection from which to initialize this enum setIllegalArgumentException
- if c
is not an EnumSet
instance and contains no elementsNullPointerException
- if c
is nullpublic static <E extends Enum<E>> EnumSet<E> complementOf(EnumSet<E> s)
E
- The class of the elements in the enum sets
- the enum set from whose complement to initialize this enum setNullPointerException
- if s
is nullpublic static <E extends Enum<E>> EnumSet<E> of(E e)
E
- The class of the specified element and of the sete
- the element that this set is to contain initiallyNullPointerException
- if e
is nullpublic static <E extends Enum<E>> EnumSet<E> of(E e1, E e2)
E
- The class of the parameter elements and of the sete1
- an element that this set is to contain initiallye2
- another element that this set is to contain initiallyNullPointerException
- if any parameters are nullpublic static <E extends Enum<E>> EnumSet<E> of(E e1, E e2, E e3)
E
- The class of the parameter elements and of the sete1
- an element that this set is to contain initiallye2
- another element that this set is to contain initiallye3
- another element that this set is to contain initiallyNullPointerException
- if any parameters are nullpublic static <E extends Enum<E>> EnumSet<E> of(E e1, E e2, E e3, E e4)
E
- The class of the parameter elements and of the sete1
- an element that this set is to contain initiallye2
- another element that this set is to contain initiallye3
- another element that this set is to contain initiallye4
- another element that this set is to contain initiallyNullPointerException
- if any parameters are nullpublic static <E extends Enum<E>> EnumSet<E> of(E e1, E e2, E e3, E e4, E e5)
E
- The class of the parameter elements and of the sete1
- an element that this set is to contain initiallye2
- another element that this set is to contain initiallye3
- another element that this set is to contain initiallye4
- another element that this set is to contain initiallye5
- another element that this set is to contain initiallyNullPointerException
- if any parameters are null@SafeVarargs public static <E extends Enum<E>> EnumSet<E> of(E first, E... rest)
E
- The class of the parameter elements and of the setfirst
- an element that the set is to contain initiallyrest
- the remaining elements the set is to contain initiallyNullPointerException
- if any of the specified elements are null, or if rest
is nullpublic static <E extends Enum<E>> EnumSet<E> range(E from, E to)
E
- The class of the parameter elements and of the setfrom
- the first element in the rangeto
- the last element in the rangeNullPointerException
- if from
or to
are nullIllegalArgumentException
- if from.compareTo(to) > 0
public EnumSet<E> clone()
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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.
Various third party code in OpenJDK is licensed under different licenses (see Debian package).
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https://docs.oracle.com/en/java/javase/21/docs/api/java.base/java/util/EnumSet.html