java.util

Class EnumSet<E,extends,Enum,E>

Implemented Interfaces:
Cloneable, Collection<E>, Iterable<T>, Serializable, Set<E>

public abstract class EnumSet<E,extends,Enum,E>
extends AbstractSet<E>
implements Cloneable, Serializable

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 the specified collection is also an enum set.

The iterator returned by the iteratormethod 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 method. This is best done at creation time, to prevent accidental unsynchronized access:

 Set<MyEnum> s = Collections.synchronizedSet(EnumSet.noneOf(Foo.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, such as EnumSet and EnumSet execute in constant time if the parameter is another EnumSet instance.

This class is a member of the ../../../guide/collections/index.html"> Java Collections Framework.

Since:
1.5
See Also:
EnumMap, Serialized Form

Method Summary

EnumSet
clone()
Returns a copy of this set.
static
extends Enum> EnumSet allOf(Class elementType)
Creates an enum set containing all of the elements in the specified element type.
static
extends Enum> EnumSet complementOf(EnumSet 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.
static
extends Enum> EnumSet copyOf(Collection c)
Creates an enum set initialized from the specified collection.
static
extends Enum> EnumSet copyOf(EnumSet s)
Creates an enum set with the same element type as the specified enum set, initially containing the same elements (if any).
static
extends Enum> EnumSet noneOf(Class elementType)
Creates an empty enum set with the specified element type.
static
extends Enum> EnumSet of(E e)
Creates an enum set initially containing the specified element.
static
extends Enum> EnumSet of(E e1, E e2)
Creates an enum set initially containing the specified elements.
static
extends Enum> EnumSet of(E e1, E e2, E e3)
Creates an enum set initially containing the specified elements.
static
extends Enum> EnumSet of(E e1, E e2, E e3, E e4)
Creates an enum set initially containing the specified elements.
static
extends Enum> EnumSet of(E e1, E e2, E e3, E e4, E e5)
Creates an enum set initially containing the specified elements.
static
extends Enum> EnumSet of(E first, E... rest)
Creates an enum set initially containing the specified elements.
static
extends Enum> EnumSet 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 inherited from class java.util.AbstractSet<E>

equals, hashCode, removeAll

Methods inherited from class java.util.AbstractCollection<E>

T[] toArray, add, addAll, clear, contains, containsAll, isEmpty, iterator, remove, removeAll, retainAll, size, toArray, toString

Methods inherited from class java.lang.Object

clone, equals, extends Object> getClass, finalize, hashCode, notify, notifyAll, toString, wait, wait, wait

Method Details

clone

public EnumSet clone()
Returns a copy of this set.
Overrides:
clone in interface Object
Returns:
a copy of this set.

extends Enum> EnumSet allOf

public static extends Enum> EnumSet allOf(Class elementType)
Creates an enum set containing all of the elements in the specified element type.
Parameters:
elementType - the class object of the element type for this enum set
Throws:
NullPointerException - if elementType is null

extends Enum> EnumSet complementOf

public static extends Enum> EnumSet complementOf(EnumSet 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:
s - the enum set from whose complement to initialize this enum set
Throws:
NullPointerException - if s is null

extends Enum> EnumSet copyOf

public static extends Enum> EnumSet copyOf(Collection c)
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:
c - the collection from which to initialize this enum set
Throws:
IllegalArgumentException - if c is not an EnumSet instance and contains no elements
NullPointerException - if c is null

extends Enum> EnumSet copyOf

public static extends Enum> EnumSet copyOf(EnumSet s)
Creates an enum set with the same element type as the specified enum set, initially containing the same elements (if any).
Parameters:
s - the enum set from which to initialize this enum set
Throws:
NullPointerException - if s is null

extends Enum> EnumSet noneOf

public static extends Enum> EnumSet noneOf(Class elementType)
Creates an empty enum set with the specified element type.
Parameters:
elementType - the class object of the element type for this enum set
Throws:
NullPointerException - if elementType is null

extends Enum> EnumSet of

public static extends Enum> EnumSet of(E e)
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 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 element that this set is to contain initially
Returns:
an enum set initially containing the specified element
Throws:
NullPointerException - if e is null

extends Enum> EnumSet of

public static extends Enum> EnumSet of(E e1,
                                                E e2)
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 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:
e1 - an element that this set is to contain initially
e2 - 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

extends Enum> EnumSet of

public static extends Enum> EnumSet of(E e1,
                                                E e2,
                                                E e3)
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 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:
e1 - an element that this set is to contain initially
e2 - another element that this set is to contain initially
e3 - 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

extends Enum> EnumSet of

public static extends Enum> EnumSet of(E e1,
                                                E e2,
                                                E e3,
                                                E e4)
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 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:
e1 - an element that this set is to contain initially
e2 - another element that this set is to contain initially
e3 - another element that this set is to contain initially
e4 - 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

extends Enum> EnumSet of

public static extends Enum> EnumSet of(E e1,
                                                E e2,
                                                E e3,
                                                E e4,
                                                E e5)
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 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:
e1 - an element that this set is to contain initially
e2 - another element that this set is to contain initially
e3 - another element that this set is to contain initially
e4 - another element that this set is to contain initially
e5 - 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

extends Enum> EnumSet of

public static extends Enum> EnumSet of(E first,
                                                E... rest)
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:
first - an element that the set is to contain initially
rest - 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 if rest is null

extends Enum> EnumSet range

public static extends Enum> EnumSet 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:
from - the first element in the range
to - 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 - if first or last are null
IllegalArgumentException - if first.compareTo(last) > 0