com.google.common.collect.ImmutableCollection<E>
com.google.common.collect.ImmutableMultiset<E>
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java.lang.Object
public class ImmutableMultiset<E>
An immutable hash-based multiset. Does not permit null elements.
Its iterator orders elements according to the first appearance of the element among the items passed to the factory method or builder. When the multiset contains multiple instances of an element, those instances are consecutive in the iteration order.
| Nested Class Summary | |
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static class |
ImmutableMultiset.Builder<E>
A builder for creating immutable multiset instances, especially public static final multisets ("constant multisets"). |
| Nested classes/interfaces inherited from interface com.google.common.collect.Multiset |
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Multiset.Entry<E> |
| Method Summary | ||
|---|---|---|
int |
add(E element,
int occurrences)
Guaranteed to throw an exception and leave the collection unmodified. |
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static
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builder()
Returns a new builder. |
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boolean |
contains(Object element)
Determines whether this multiset contains the specified element. |
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static
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copyOf(Iterable<? extends E> elements)
Returns an immutable multiset containing the given elements. |
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static
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copyOf(Iterator<? extends E> elements)
Returns an immutable multiset containing the given elements. |
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int |
count(Object element)
Returns the number of occurrences of an element in this multiset (the count of the element). |
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Set<E> |
elementSet()
Returns the set of distinct elements contained in this multiset. |
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Set<Multiset.Entry<E>> |
entrySet()
Returns a view of the contents of this multiset, grouped into Multiset.Entry instances, each providing an element of the multiset and
the count of that element. |
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boolean |
equals(Object object)
Compares the specified object with this multiset for equality. |
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int |
hashCode()
Returns the hash code for this multiset. |
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UnmodifiableIterator<E> |
iterator()
Returns an unmodifiable iterator across the elements in this collection. |
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static
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of()
Returns the empty immutable multiset. |
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static
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of(E... elements)
Returns an immutable multiset containing the given elements. |
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int |
remove(Object element,
int occurrences)
Guaranteed to throw an exception and leave the collection unmodified. |
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int |
setCount(E element,
int count)
Guaranteed to throw an exception and leave the collection unmodified. |
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boolean |
setCount(E element,
int oldCount,
int newCount)
Guaranteed to throw an exception and leave the collection unmodified. |
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int |
size()
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String |
toString()
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| Methods inherited from class com.google.common.collect.ImmutableCollection |
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add, addAll, asList, clear, containsAll, isEmpty, remove, removeAll, retainAll, toArray, toArray |
| Methods inherited from class java.lang.Object |
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clone, finalize, getClass, notify, notifyAll, wait, wait, wait |
| Methods inherited from interface com.google.common.collect.Multiset |
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add, containsAll, remove, removeAll, retainAll |
| Methods inherited from interface java.util.Collection |
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addAll, clear, isEmpty, toArray, toArray |
| Method Detail |
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public static <E> ImmutableMultiset<E> of()
public static <E> ImmutableMultiset<E> of(E... elements)
The multiset is ordered by the first occurrence of each element. For
example, ImmutableMultiset.of(2, 3, 1, 3) yields a multiset with
elements in the order 2, 3, 3, 1.
NullPointerException - if any of elements is nullpublic static <E> ImmutableMultiset<E> copyOf(Iterable<? extends E> elements)
The multiset is ordered by the first occurrence of each element. For
example, ImmutableMultiset.copyOf(Arrays.asList(2, 3, 1, 3)) yields
a multiset with elements in the order 2, 3, 3, 1.
Note that if c is a Collection<String>, then ImmutableMultiset.copyOf(c) returns an ImmutableMultiset<String>
containing each of the strings in c, while
ImmutableMultiset.of(c) returns an
ImmutableMultiset<Collection<String>> containing one element (the
given collection itself).
Note: Despite what the method name suggests, if elements
is an ImmutableMultiset, no copy will actually be performed, and
the given multiset itself will be returned.
NullPointerException - if any of elements is nullpublic static <E> ImmutableMultiset<E> copyOf(Iterator<? extends E> elements)
The multiset is ordered by the first occurrence of each element. For
example,
ImmutableMultiset.copyOf(Arrays.asList(2, 3, 1, 3).iterator())
yields a multiset with elements in the order 2, 3, 3, 1.
NullPointerException - if any of elements is null
public int count(@Nullable
Object element)
MultisetObject.equals(java.lang.Object)-based
multiset, this gives the same result as Collections.frequency(java.util.Collection, java.lang.Object)
(which would presumably perform more poorly).
Note: the utility method Iterables.frequency(java.lang.Iterable, java.lang.Object) generalizes
this operation; it correctly delegates to this method when dealing with a
multiset, but it can also accept any other iterable type.
count in interface Multiset<E>element - the element to count occurrences of
public UnmodifiableIterator<E> iterator()
ImmutableCollection
iterator in interface Multiset<E>iterator in interface Iterable<E>iterator in interface Collection<E>iterator in class ImmutableCollection<E>public int size()
size in interface Collection<E>
public boolean contains(@Nullable
Object element)
MultisetThis method refines Collection.contains(java.lang.Object) to further specify that
it may not throw an exception in response to element being
null or of the wrong type.
contains in interface Multiset<E>contains in interface Collection<E>contains in class ImmutableCollection<E>element - the element to check for
true if this multiset contains at least one occurrence of
the element
public int add(E element,
int occurrences)
add in interface Multiset<E>element - the element to add occurrences of; may be null only
if explicitly allowed by the implementationoccurrences - the number of occurrences of the element to add. May be
zero, in which case no change will be made.
UnsupportedOperationException - always
public int remove(Object element,
int occurrences)
remove in interface Multiset<E>element - the element to conditionally remove occurrences ofoccurrences - the number of occurrences of the element to remove. May
be zero, in which case no change will be made.
UnsupportedOperationException - always
public int setCount(E element,
int count)
setCount in interface Multiset<E>element - the element to add or remove occurrences of; may be null
only if explicitly allowed by the implementationcount - the desired count of the element in this multiset
UnsupportedOperationException - always
public boolean setCount(E element,
int oldCount,
int newCount)
setCount in interface Multiset<E>element - the element to conditionally set the count of; may be null
only if explicitly allowed by the implementationoldCount - the expected present count of the element in this multisetnewCount - the desired count of the element in this multiset
true if the condition for modification was met. This
implies that the multiset was indeed modified, unless
oldCount == newCount.
UnsupportedOperationException - always
public boolean equals(@Nullable
Object object)
Multisettrue if the given object is also a multiset and contains equal
elements with equal counts, regardless of order.
equals in interface Multiset<E>equals in interface Collection<E>equals in class Objectpublic int hashCode()
Multiset(element == null ? 0 : element.hashCode()) ^ count(element)over all distinct elements in the multiset. It follows that a multiset and its entry set always have the same hash code.
hashCode in interface Multiset<E>hashCode in interface Collection<E>hashCode in class Objectpublic String toString()
MultisetIt is recommended, though not mandatory, that this method return the
result of invoking Multiset.toString() on the Multiset.entrySet(), yielding a
result such as
[a x 3, c, d x 2, e]
toString in interface Multiset<E>toString in class ImmutableCollection<E>public Set<E> elementSet()
MultisetIf the element set supports any removal operations, these necessarily cause all occurrences of the removed element(s) to be removed from the multiset. Implementations are not expected to support the add operations, although this is possible.
A common use for the element set is to find the number of distinct
elements in the multiset: elementSet().size().
elementSet in interface Multiset<E>public Set<Multiset.Entry<E>> entrySet()
MultisetMultiset.Entry instances, each providing an element of the multiset and
the count of that element. This set contains exactly one entry for each
distinct element in the multiset (thus it always has the same size as the
Multiset.elementSet()). The order of the elements in the element set is
unspecified.
The entry set is backed by the same data as the multiset, so any change
to either is immediately reflected in the other. However, multiset changes
may or may not be reflected in any Entry instances already
retrieved from the entry set (this is implementation-dependent).
Furthermore, implementations are not required to support modifications to
the entry set at all, and the Entry instances themselves don't
even have methods for modification. See the specific implementation class
for more details on how its entry set handles modifications.
entrySet in interface Multiset<E>public static <E> ImmutableMultiset.Builder<E> builder()
ImmutableMultiset.Builder constructor.
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