@GwtCompatible(serializable=true, emulated=true) public abstract class ImmutableSet<E> extends ImmutableCollection<E> implements java.util.Set<E>
Set with reliable, user-specified
iteration order. Does not permit null elements.
Unlike Collections.unmodifiableSet(java.util.Set<? extends T>), which is a view of a
separate collection that can still change, an instance of this class contains
its own private data and will never change. This class is convenient
for public static final sets ("constant sets") and also lets you
easily make a "defensive copy" of a set provided to your class by a caller.
Warning: Like most sets, an ImmutableSet will not function
correctly if an element is modified after being placed in the set. For this
reason, and to avoid general confusion, it is strongly recommended to place
only immutable objects into this collection.
This class has been observed to perform significantly better than HashSet for objects with very fast Object.hashCode() implementations
(as a well-behaved immutable object should). While this class's factory
methods create hash-based instances, the ImmutableSortedSet subclass
performs binary searches instead.
Note: Although this class is not final, it cannot be subclassed outside its package as it has no public or protected constructors. Thus, instances of this type are guaranteed to be immutable.
See the Guava User Guide article on immutable collections.
ImmutableList,
ImmutableMap,
Serialized Form| Modifier and Type | Class and Description |
|---|---|
static class |
ImmutableSet.Builder<E>
A builder for creating immutable set instances, especially
public
static final sets ("constant sets"). |
private static class |
ImmutableSet.SerializedForm |
ImmutableCollection.ArrayBasedBuilder<E>| Modifier and Type | Field and Description |
|---|---|
private static int |
CUTOFF |
private static double |
DESIRED_LOAD_FACTOR |
(package private) static int |
MAX_TABLE_SIZE |
| Constructor and Description |
|---|
ImmutableSet() |
| Modifier and Type | Method and Description |
|---|---|
static <E> ImmutableSet.Builder<E> |
builder()
Returns a new builder.
|
(package private) static int |
chooseTableSize(int setSize)
Returns an array size suitable for the backing array of a hash table that
uses open addressing with linear probing in its implementation.
|
private static <E> ImmutableSet<E> |
construct(int n,
java.lang.Object... elements)
Constructs an
ImmutableSet from the first n elements of the specified array. |
static <E> ImmutableSet<E> |
copyOf(java.util.Collection<? extends E> elements)
Returns an immutable set containing the given elements, in order.
|
static <E> ImmutableSet<E> |
copyOf(E[] elements)
Returns an immutable set containing the given elements, in order.
|
static <E> ImmutableSet<E> |
copyOf(java.lang.Iterable<? extends E> elements)
Returns an immutable set containing the given elements, in order.
|
static <E> ImmutableSet<E> |
copyOf(java.util.Iterator<? extends E> elements)
Returns an immutable set containing the given elements, in order.
|
private static <E extends java.lang.Enum<E>> |
copyOfEnumSet(java.util.EnumSet<E> enumSet) |
boolean |
equals(java.lang.Object object) |
int |
hashCode() |
(package private) boolean |
isHashCodeFast()
Returns
true if the hashCode() method runs quickly. |
abstract UnmodifiableIterator<E> |
iterator()
Returns an unmodifiable iterator across the elements in this collection.
|
static <E> ImmutableSet<E> |
of()
Returns the empty immutable set.
|
static <E> ImmutableSet<E> |
of(E element)
Returns an immutable set containing a single element.
|
static <E> ImmutableSet<E> |
of(E e1,
E e2)
Returns an immutable set containing the given elements, in order.
|
static <E> ImmutableSet<E> |
of(E e1,
E e2,
E e3)
Returns an immutable set containing the given elements, in order.
|
static <E> ImmutableSet<E> |
of(E e1,
E e2,
E e3,
E e4)
Returns an immutable set containing the given elements, in order.
|
static <E> ImmutableSet<E> |
of(E e1,
E e2,
E e3,
E e4,
E e5)
Returns an immutable set containing the given elements, in order.
|
static <E> ImmutableSet<E> |
of(E e1,
E e2,
E e3,
E e4,
E e5,
E e6,
E... others)
Returns an immutable set containing the given elements, in order.
|
(package private) java.lang.Object |
writeReplace() |
add, addAll, asList, clear, contains, copyIntoArray, createAsList, isPartialView, remove, removeAll, retainAll, toArray, toArrayclone, finalize, getClass, notify, notifyAll, wait, wait, waitstatic final int MAX_TABLE_SIZE
private static final double DESIRED_LOAD_FACTOR
private static final int CUTOFF
public static <E> ImmutableSet<E> of()
Collections.emptySet(), and is preferable mainly for consistency
and maintainability of your code.public static <E> ImmutableSet<E> of(E element)
Collections.singleton(T), but will not accept
a null element. It is preferable mainly for consistency and
maintainability of your code.public static <E> ImmutableSet<E> of(E e1, E e2)
Object.equals(java.lang.Object)) after the
first are ignored.java.lang.NullPointerException - if any element is nullpublic static <E> ImmutableSet<E> of(E e1, E e2, E e3)
Object.equals(java.lang.Object)) after the
first are ignored.java.lang.NullPointerException - if any element is nullpublic static <E> ImmutableSet<E> of(E e1, E e2, E e3, E e4)
Object.equals(java.lang.Object)) after the
first are ignored.java.lang.NullPointerException - if any element is nullpublic static <E> ImmutableSet<E> of(E e1, E e2, E e3, E e4, E e5)
Object.equals(java.lang.Object)) after the
first are ignored.java.lang.NullPointerException - if any element is nullpublic static <E> ImmutableSet<E> of(E e1, E e2, E e3, E e4, E e5, E e6, E... others)
Object.equals(java.lang.Object)) after the
first are ignored.java.lang.NullPointerException - if any element is nullprivate static <E> ImmutableSet<E> construct(int n, java.lang.Object... elements)
ImmutableSet from the first n elements of the specified array.
If k is the size of the returned ImmutableSet, then the unique elements of
elements will be in the first k positions, and elements[i] == null for
k <= i < n.
This may modify elements. Additionally, if n == elements.length and
elements contains no duplicates, elements may be used without copying in the
returned ImmutableSet, in which case it may no longer be modified.
elements may contain only values of type E.
java.lang.NullPointerException - if any of the first n elements of elements is
nullstatic int chooseTableSize(int setSize)
Do not call this method with setSize < 2.
public static <E> ImmutableSet<E> copyOf(E[] elements)
Object.equals(java.lang.Object)) after the
first are ignored.java.lang.NullPointerException - if any of elements is nullpublic static <E> ImmutableSet<E> copyOf(java.lang.Iterable<? extends E> elements)
Object.equals(java.lang.Object)) after the
first are ignored. This method iterates over elements at most once.
Note that if s is a Set<String>, then ImmutableSet.copyOf(s) returns an ImmutableSet<String> containing
each of the strings in s, while ImmutableSet.of(s) returns
a ImmutableSet<Set<String>> containing one element (the given set
itself).
Despite the method name, this method attempts to avoid actually copying the data when it is safe to do so. The exact circumstances under which a copy will or will not be performed are undocumented and subject to change.
java.lang.NullPointerException - if any of elements is nullpublic static <E> ImmutableSet<E> copyOf(java.util.Iterator<? extends E> elements)
Object.equals(java.lang.Object)) after the
first are ignored.java.lang.NullPointerException - if any of elements is nullpublic static <E> ImmutableSet<E> copyOf(java.util.Collection<? extends E> elements)
Object.equals(java.lang.Object)) after the
first are ignored. This method iterates over elements at most
once.
Note that if s is a Set<String>, then ImmutableSet.copyOf(s) returns an ImmutableSet<String> containing
each of the strings in s, while ImmutableSet.of(s) returns
a ImmutableSet<Set<String>> containing one element (the given set
itself).
Note: Despite what the method name suggests, copyOf will
return constant-space views, rather than linear-space copies, of some
inputs known to be immutable. For some other immutable inputs, such as key
sets of an ImmutableMap, it still performs a copy in order to avoid
holding references to the values of the map. The heuristics used in this
decision are undocumented and subject to change except that:
ImmutableSortedSet.ImmutableSet.copyOf() is idempotent with respect to pointer
equality.This method is safe to use even when elements is a synchronized
or concurrent collection that is currently being modified by another
thread.
java.lang.NullPointerException - if any of elements is nullprivate static <E extends java.lang.Enum<E>> ImmutableSet<E> copyOfEnumSet(java.util.EnumSet<E> enumSet)
boolean isHashCodeFast()
true if the hashCode() method runs quickly.public boolean equals(@Nullable
java.lang.Object object)
public int hashCode()
public abstract UnmodifiableIterator<E> iterator()
ImmutableCollectionjava.lang.Object writeReplace()
writeReplace in class ImmutableCollection<E>public static <E> ImmutableSet.Builder<E> builder()
ImmutableSet.Builder constructor.