Package com.google.common.collect

Class ImmutableSet<E>

java.lang.Object

java.util.AbstractCollection<E>

com.google.common.collect.ImmutableCollection<E>

com.google.common.collect.ImmutableSet<E>

All Implemented Interfaces:

Serializable, Iterable<E>, Collection<E>, Set<E>

Direct Known Subclasses:

ImmutableSortedSet

@GwtCompatible(serializable=true,
               emulated=true)
public abstract class ImmutableSet<E>
extends ImmutableCollection<E>
implements Set<E>

A Set whose contents will never change, with many other important properties detailed at ImmutableCollection.

Since:

2.0

See Also:

Serialized Form

Nested Class Summary

Nested Classes

Modifier and Type	Class	Description
static class	ImmutableSet.Builder<E>	A builder for creating ImmutableSet instances.

Method Summary

Modifier and Type	Method	Description
static <E> ImmutableSet.Builder<E>	builder()	Returns a new builder.
static <E> ImmutableSet.Builder<E>	builderWithExpectedSize(int expectedSize)	Returns a new builder, expecting the specified number of distinct elements to be added.
static <E> ImmutableSet<E>	copyOf(E[] elements)	Returns an immutable set containing each of elements, minus duplicates, in the order each appears first in the source array.
static <E> ImmutableSet<E>	copyOf(Iterable<? extends E> elements)	Returns an immutable set containing each of elements, minus duplicates, in the order each appears first in the source iterable.
static <E> ImmutableSet<E>	copyOf(Collection<? extends E> elements)	Returns an immutable set containing each of elements, minus duplicates, in the order each appears first in the source collection.
static <E> ImmutableSet<E>	copyOf(Iterator<? extends E> elements)	Returns an immutable set containing each of elements, minus duplicates, in the order each appears first in the source iterator.
boolean	equals(Object object)
int	hashCode()
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 e1)	Returns an immutable set containing the given element.
static <E> ImmutableSet<E>	of(E e1, E e2)	Returns an immutable set containing the given elements, minus duplicates, in the order each was first specified.
static <E> ImmutableSet<E>	of(E e1, E e2, E e3)	Returns an immutable set containing the given elements, minus duplicates, in the order each was first specified.
static <E> ImmutableSet<E>	of(E e1, E e2, E e3, E e4)	Returns an immutable set containing the given elements, minus duplicates, in the order each was first specified.
static <E> ImmutableSet<E>	of(E e1, E e2, E e3, E e4, E e5)	Returns an immutable set containing the given elements, minus duplicates, in the order each was first specified.
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, minus duplicates, in the order each was first specified.
static <E> Collector<E,?,ImmutableSet<E>>	toImmutableSet()	Returns a Collector that accumulates the input elements into a new ImmutableSet.

Methods inherited from class com.google.common.collect.ImmutableCollection

add, addAll, asList, clear, contains, remove, removeAll, removeIf, retainAll, spliterator, toArray, toArray

Methods inherited from class java.util.AbstractCollection

containsAll, isEmpty, size, toString

Methods inherited from class java.lang.Object

clone, finalize, getClass, notify, notifyAll, wait, wait, wait

Methods inherited from interface java.util.Collection

parallelStream, removeIf, stream, toArray

Methods inherited from interface java.lang.Iterable

forEach

Methods inherited from interface java.util.Set

add, addAll, clear, contains, containsAll, isEmpty, remove, removeAll, retainAll, size, spliterator, toArray, toArray

Method Detail

toImmutableSet

public static <E> Collector<E,?,ImmutableSet<E>> toImmutableSet()

Returns a Collector that accumulates the input elements into a new ImmutableSet. Elements appear in the resulting set in the encounter order of the stream; if the stream contains duplicates (according to Object.equals(Object)), only the first duplicate in encounter order will appear in the result.

Since:

21.0

of

public static <E> ImmutableSet<E> of()

Returns the empty immutable set. Preferred over Collections.emptySet() for code consistency, and because the return type conveys the immutability guarantee.

Performance note: the instance returned is a singleton.

of

public static <E> ImmutableSet<E> of(E e1)

Returns an immutable set containing the given element. Preferred over Collections.singleton(T) for code consistency, null rejection, and because the return type conveys the immutability guarantee.

of

public static <E> ImmutableSet<E> of(E e1,
                                     E e2)

Returns an immutable set containing the given elements, minus duplicates, in the order each was first specified. That is, if multiple elements are equal, all except the first are ignored.

of

public static <E> ImmutableSet<E> of(E e1,
                                     E e2,
                                     E e3)

Returns an immutable set containing the given elements, minus duplicates, in the order each was first specified. That is, if multiple elements are equal, all except the first are ignored.

of

public static <E> ImmutableSet<E> of(E e1,
                                     E e2,
                                     E e3,
                                     E e4)

Returns an immutable set containing the given elements, minus duplicates, in the order each was first specified. That is, if multiple elements are equal, all except the first are ignored.

of

public static <E> ImmutableSet<E> of(E e1,
                                     E e2,
                                     E e3,
                                     E e4,
                                     E e5)

Returns an immutable set containing the given elements, minus duplicates, in the order each was first specified. That is, if multiple elements are equal, all except the first are ignored.

of

@SafeVarargs
public 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, minus duplicates, in the order each was first specified. That is, if multiple elements are equal, all except the first are ignored.

The array others must not be longer than Integer.MAX_VALUE - 6.

Since:

3.0 (source-compatible since 2.0)

copyOf

public static <E> ImmutableSet<E> copyOf(Collection<? extends E> elements)

Returns an immutable set containing each of elements, minus duplicates, in the order each appears first in the source collection.

Performance note: This method will sometimes recognize that the actual copy operation is unnecessary; for example, copyOf(copyOf(anArrayList)) will copy the data only once. This reduces the expense of habitually making defensive copies at API boundaries. However, the precise conditions for skipping the copy operation are undefined.

Throws:

NullPointerException - if any of elements is null

Since:

7.0 (source-compatible since 2.0)

copyOf

public static <E> ImmutableSet<E> copyOf(Iterable<? extends E> elements)

Returns an immutable set containing each of elements, minus duplicates, in the order each appears first in the source iterable. This method iterates over elements only once.

Performance note: This method will sometimes recognize that the actual copy operation is unnecessary; for example, copyOf(copyOf(anArrayList)) should copy the data only once. This reduces the expense of habitually making defensive copies at API boundaries. However, the precise conditions for skipping the copy operation are undefined.

Throws:

NullPointerException - if any of elements is null

copyOf

public static <E> ImmutableSet<E> copyOf(Iterator<? extends E> elements)

Returns an immutable set containing each of elements, minus duplicates, in the order each appears first in the source iterator.

Throws:

NullPointerException - if any of elements is null

copyOf

public static <E> ImmutableSet<E> copyOf(E[] elements)

Returns an immutable set containing each of elements, minus duplicates, in the order each appears first in the source array.

Throws:

NullPointerException - if any of elements is null

Since:

3.0

equals

public boolean equals(@CheckForNull
                      Object object)

Specified by:

equals in interface Collection<E>

Specified by:

equals in interface Set<E>

Overrides:

equals in class Object

hashCode

public int hashCode()

Specified by:

hashCode in interface Collection<E>

Specified by:

hashCode in interface Set<E>

Overrides:

hashCode in class Object

iterator

public abstract UnmodifiableIterator<E> iterator()

Description copied from class: ImmutableCollection

Returns an unmodifiable iterator across the elements in this collection.

Specified by:

iterator in interface Collection<E>

Specified by:

iterator in interface Iterable<E>

Specified by:

iterator in interface Set<E>

Specified by:

iterator in class ImmutableCollection<E>

builder

public static <E> ImmutableSet.Builder<E> builder()

Returns a new builder. The generated builder is equivalent to the builder created by the ImmutableSet.Builder constructor.

builderWithExpectedSize

public static <E> ImmutableSet.Builder<E> builderWithExpectedSize(int expectedSize)

Returns a new builder, expecting the specified number of distinct elements to be added.

If expectedSize is exactly the number of distinct elements added to the builder before ImmutableSet.Builder.build() is called, the builder is likely to perform better than an unsized builder() would have.

It is not specified if any performance benefits apply if expectedSize is close to, but not exactly, the number of distinct elements added to the builder.

Since:

23.1