JavaTM 2 Platform Std. Ed. v1.6.0
java.util
Class EnumSet<E extends Enum<E>>
java.lang.Object
java.util.AbstractCollection<E>
java.util.AbstractSet<E>
java.util.EnumSet<E>
- All Implemented Interfaces:
- Serializable, Cloneable, Iterable<E>, Collection<E>, 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 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)
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:
EnumMap
Method Summary |
static
|
allOf(Class<E> elementType)
Creates an enum set containing all of the elements in the specified
element type. |
EnumSet<E> |
clone()
Returns a copy of this set. |
static
|
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. |
static
|
copyOf(Collection<E> c)
Creates an enum set initialized from the specified collection. |
static
|
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). |
static
|
noneOf(Class<E> elementType)
Creates an empty enum set with the specified element type. |
static
|
of(E e)
Creates an enum set initially containing the specified element. |
static
|
of(E first,
E... rest)
Creates an enum set initially containing the specified elements. |
static
|
of(E e1,
E e2)
Creates an enum set initially containing the specified elements. |
static
|
of(E e1,
E e2,
E e3)
Creates an enum set initially containing the specified elements. |
static
|
of(E e1,
E e2,
E e3,
E e4)
Creates an enum set initially containing the specified elements. |
static
|
of(E e1,
E e2,
E e3,
E e4,
E e5)
Creates an enum set initially containing the specified elements. |
static
|
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.AbstractCollection |
add, addAll, clear, contains, containsAll, isEmpty, iterator, remove, retainAll, size, toArray, toArray, toString |
Methods inherited from interface java.util.Set |
add, addAll, clear, contains, containsAll, isEmpty, iterator, remove, retainAll, size, toArray, toArray |
noneOf
public static <E extends Enum<E>> EnumSet<E> noneOf(Class<E> 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
allOf
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:
elementType - the class object of the element type for this enum
set
- Throws:
NullPointerException - if elementType is null
copyOf
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:
s - the enum set from which to initialize this enum set
- Throws:
NullPointerException - if s is null
copyOf
public static <E extends Enum<E>> EnumSet<E> copyOf(Collection<E> 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
complementOf
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:
s - the enum set from whose complement to initialize this enum set
- Throws:
NullPointerException - if s is null
of
public static <E extends Enum<E>> EnumSet<E> 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 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
of
public static <E extends Enum<E>> EnumSet<E> 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 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 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
public static <E extends Enum<E>> EnumSet<E> 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 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 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
public static <E extends Enum<E>> EnumSet<E> 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 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 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
public static <E extends Enum<E>> EnumSet<E> 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 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 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
public static <E extends Enum<E>> EnumSet<E> 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 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 if rest is null
range
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:
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 - if first or last are
null
IllegalArgumentException - if first.compareTo(last) > 0
clone
public EnumSet<E> clone()
- Returns a copy of this set.
- Overrides:
clone in class Object
- Returns:
- a copy of this set
- See Also:
Cloneable
Copyright 2003 Sun Microsystems, Inc. All rights reserved
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