- Type Parameters:
E
- the enum type of elements maintained by this set
- All Implemented Interfaces:
Serializable
,Cloneable
,Iterable<E>
,Collection<E>
,Set<E>
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.
- Since:
- 1.5
- See Also:
-
Method Summary
Modifier and TypeMethodDescriptionCreates an enum set containing all of the elements in the specified element type.clone()
Returns a copy of this set.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.copyOf
(Collection<E> c) Creates an enum set initialized from the specified collection.Creates an enum set with the same element type as the specified enum set, initially containing the same elements (if any).Creates an empty enum set with the specified element type.of
(E e) Creates an enum set initially containing the specified element.of
(E e1, E e2) Creates an enum set initially containing the specified elements.of
(E first, E... rest) Creates an enum set initially containing the specified elements.of
(E e1, E e2, E e3) Creates an enum set initially containing the specified elements.of
(E e1, E e2, E e3, E e4) Creates an enum set initially containing the specified elements.of
(E e1, E e2, E e3, E e4, E e5) Creates an enum set initially containing the specified elements.range
(E from, E to) Creates an enum set initially containing all of the elements in the range defined by the two specified endpoints.Methods declared in class java.util.AbstractSet
equals, hashCode, removeAll
Methods declared in class java.util.AbstractCollection
add, addAll, clear, contains, containsAll, isEmpty, iterator, remove, retainAll, toArray, toArray, toString
Methods declared in interface java.util.Collection
parallelStream, removeIf, stream, toArray
-
Method Details
-
noneOf
Creates an empty enum set with the specified element type.- Type Parameters:
E
- The class of the elements in the set- Parameters:
elementType
- the class object of the element type for this enum set- Returns:
- An empty enum set of the specified type.
- Throws:
NullPointerException
- ifelementType
is null
-
allOf
Creates an enum set containing all of the elements in the specified element type.- Type Parameters:
E
- The class of the elements in the set- Parameters:
elementType
- the class object of the element type for this enum set- Returns:
- An enum set containing all the elements in the specified type.
- Throws:
NullPointerException
- ifelementType
is null
-
copyOf
Creates an enum set with the same element type as the specified enum set, initially containing the same elements (if any).- Type Parameters:
E
- The class of the elements in the set- Parameters:
s
- the enum set from which to initialize this enum set- Returns:
- A copy of the specified enum set.
- Throws:
NullPointerException
- ifs
is null
-
copyOf
Creates an enum set initialized from the specified collection. If the specified collection is anEnumSet
instance, this static factory method behaves identically tocopyOf(EnumSet)
. Otherwise, the specified collection must contain at least one element (in order to determine the new enum set's element type).- Type Parameters:
E
- The class of the elements in the collection- Parameters:
c
- the collection from which to initialize this enum set- Returns:
- An enum set initialized from the given collection.
- Throws:
IllegalArgumentException
- ifc
is not anEnumSet
instance and contains no elementsNullPointerException
- ifc
is null
-
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.- Type Parameters:
E
- The class of the elements in the enum set- Parameters:
s
- the enum set from whose complement to initialize this enum set- Returns:
- The complement of the specified set in this set
- Throws:
NullPointerException
- ifs
is null
-
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.- Type Parameters:
E
- The class of the specified element and of the set- Parameters:
e
- the element that this set is to contain initially- Returns:
- an enum set initially containing the specified element
- Throws:
NullPointerException
- ife
is null
-
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.- Type Parameters:
E
- The class of the parameter elements and of the set- Parameters:
e1
- an element that this set is to contain initiallye2
- another element that this set is to contain initially- Returns:
- an enum set initially containing the specified elements
- Throws:
NullPointerException
- if any parameters are null
-
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.- Type Parameters:
E
- The class of the parameter elements and of the set- Parameters:
e1
- 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 initially- Returns:
- an enum set initially containing the specified elements
- Throws:
NullPointerException
- if any parameters are null
-
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.- Type Parameters:
E
- The class of the parameter elements and of the set- Parameters:
e1
- 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 initially- Returns:
- an enum set initially containing the specified elements
- Throws:
NullPointerException
- if any parameters are null
-
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.- Type Parameters:
E
- The class of the parameter elements and of the set- Parameters:
e1
- 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 initially- Returns:
- an enum set initially containing the specified elements
- Throws:
NullPointerException
- if any parameters are null
-
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.- Type Parameters:
E
- The class of the parameter elements and of the set- Parameters:
first
- an element that the set is to contain initiallyrest
- the remaining elements the set is to contain initially- Returns:
- an enum set initially containing the specified elements
- Throws:
NullPointerException
- if any of the specified elements are null, or ifrest
is null
-
range
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.- Type Parameters:
E
- The class of the parameter elements and of the set- Parameters:
from
- the first element in the rangeto
- the last element in the range- Returns:
- an enum set initially containing all of the elements in the range defined by the two specified endpoints
- Throws:
NullPointerException
- iffrom
orto
are nullIllegalArgumentException
- iffrom.compareTo(to) > 0
-
clone
-