Package com.google.common.collect

Class ImmutableMultiset<E>

java.lang.Object

java.util.AbstractCollection<E>

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

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

All Implemented Interfaces:

Multiset<E>, java.io.Serializable, java.lang.Iterable<E>, java.util.Collection<E>

Direct Known Subclasses:

ImmutableSortedMultiset

@GwtCompatible(serializable=true,
               emulated=true)
public abstract class ImmutableMultiset<E>
extends ImmutableCollection<E>
implements Multiset<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.

See the Guava User Guide article on immutable collections.

Since:

2.0 (imported from Google Collections Library)

See Also:

Serialized Form

Nested Class Summary

Nested Classes

Modifier and Type	Class	Description
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

Multiset.Entry<E>

Method Summary

Modifier and Type	Method	Description
int	add(E element, int occurrences)	Deprecated. Unsupported operation.
static <E> ImmutableMultiset.Builder<E>	builder()	Returns a new builder.
boolean	contains(java.lang.Object object)	Determines whether this multiset contains the specified element.
boolean	containsAll(java.util.Collection<?> targets)	Returns true if this multiset contains at least one occurrence of each element in the specified collection.
static <E> ImmutableMultiset<E>	copyOf(E[] elements)	Returns an immutable multiset containing the given elements.
static <E> ImmutableMultiset<E>	copyOf(java.lang.Iterable<? extends E> elements)	Returns an immutable multiset containing the given elements.
static <E> ImmutableMultiset<E>	copyOf(java.util.Iterator<? extends E> elements)	Returns an immutable multiset containing the given elements.
ImmutableSet<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.
boolean	equals(java.lang.Object object)	Compares the specified object with this multiset for equality.
int	hashCode()	Returns the hash code for this multiset.
UnmodifiableIterator<E>	iterator()	Returns an unmodifiable iterator across the elements in this collection.
static <E> ImmutableMultiset<E>	of()	Returns the empty immutable multiset.
static <E> ImmutableMultiset<E>	of(E element)	Returns an immutable multiset containing a single element.
static <E> ImmutableMultiset<E>	of(E e1, E e2)	Returns an immutable multiset containing the given elements, in order.
static <E> ImmutableMultiset<E>	of(E e1, E e2, E e3)	Returns an immutable multiset containing the given elements, in order.
static <E> ImmutableMultiset<E>	of(E e1, E e2, E e3, E e4)	Returns an immutable multiset containing the given elements, in order.
static <E> ImmutableMultiset<E>	of(E e1, E e2, E e3, E e4, E e5)	Returns an immutable multiset containing the given elements, in order.
static <E> ImmutableMultiset<E>	of(E e1, E e2, E e3, E e4, E e5, E e6, E... others)	Returns an immutable multiset containing the given elements, in order.
int	remove(java.lang.Object element, int occurrences)	Deprecated. Unsupported operation.
int	setCount(E element, int count)	Deprecated. Unsupported operation.
boolean	setCount(E element, int oldCount, int newCount)	Deprecated. Unsupported operation.
java.lang.String	toString()

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

add, addAll, asList, clear, remove, removeAll, retainAll, toArray, toArray

Methods inherited from class java.util.AbstractCollection

isEmpty, size

Methods inherited from class java.lang.Object

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

Methods inherited from interface java.util.Collection

addAll, clear, isEmpty, parallelStream, removeIf, size, spliterator, stream, toArray, toArray, toArray

Methods inherited from interface java.lang.Iterable

forEach

Methods inherited from interface com.google.common.collect.Multiset

add, count, elementSet, remove, removeAll, retainAll

Method Detail

of

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

Returns the empty immutable multiset.

of

public static <E> ImmutableMultiset<E> of(E element)

Returns an immutable multiset containing a single element.

Throws:

java.lang.NullPointerException - if element is null

Since:

6.0 (source-compatible since 2.0)

of

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

Returns an immutable multiset containing the given elements, in order.

Throws:

java.lang.NullPointerException - if any element is null

Since:

6.0 (source-compatible since 2.0)

of

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

Returns an immutable multiset containing the given elements, in order.

Throws:

java.lang.NullPointerException - if any element is null

Since:

6.0 (source-compatible since 2.0)

of

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

Returns an immutable multiset containing the given elements, in order.

Throws:

java.lang.NullPointerException - if any element is null

Since:

6.0 (source-compatible since 2.0)

of

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

Returns an immutable multiset containing the given elements, in order.

Throws:

java.lang.NullPointerException - if any element is null

Since:

6.0 (source-compatible since 2.0)

of

public static <E> ImmutableMultiset<E> of(E e1,
                                          E e2,
                                          E e3,
                                          E e4,
                                          E e5,
                                          E e6,
                                          E... others)

Returns an immutable multiset containing the given elements, in order.

Throws:

java.lang.NullPointerException - if any element is null

Since:

6.0 (source-compatible since 2.0)

copyOf

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

Returns an immutable multiset containing the given elements.

The multiset is ordered by the first occurrence of each element. For example, ImmutableMultiset.copyOf([2, 3, 1, 3]) yields a multiset with elements in the order 2, 3, 3, 1.

Throws:

java.lang.NullPointerException - if any of elements is null

Since:

6.0

copyOf

public static <E> ImmutableMultiset<E> copyOf(java.lang.Iterable<? extends E> elements)

Returns an immutable multiset containing the given 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.

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.

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.

Throws:

java.lang.NullPointerException - if any of elements is null

copyOf

public static <E> ImmutableMultiset<E> copyOf(java.util.Iterator<? extends E> elements)

Returns an immutable multiset containing the given 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.

Throws:

java.lang.NullPointerException - if any of elements is null

iterator

public UnmodifiableIterator<E> iterator()

Description copied from class: ImmutableCollection

Returns an unmodifiable iterator across the elements in this collection.

Specified by:

iterator in interface java.util.Collection<E>

Specified by:

iterator in interface java.lang.Iterable<E>

Specified by:

iterator in interface Multiset<E>

Specified by:

iterator in class ImmutableCollection<E>

contains

public boolean contains(@Nullable
                        java.lang.Object object)

Description copied from interface: Multiset

Determines whether this multiset contains the specified element.

This 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.

Specified by:

contains in interface java.util.Collection<E>

Specified by:

contains in interface Multiset<E>

Overrides:

contains in class ImmutableCollection<E>

Parameters:

object - the element to check for

Returns:

true if this multiset contains at least one occurrence of the element

containsAll

public boolean containsAll(java.util.Collection<?> targets)

Description copied from interface: Multiset

Returns true if this multiset contains at least one occurrence of each element in the specified collection.

This method refines Collection.containsAll(java.util.Collection<?>) to further specify that it may not throw an exception in response to any of elements being null or of the wrong type.

Note: this method does not take into account the occurrence count of an element in the two collections; it may still return true even if elements contains several occurrences of an element and this multiset contains only one. This is no different than any other collection type like List, but it may be unexpected to the user of a multiset.

Specified by:

containsAll in interface java.util.Collection<E>

Specified by:

containsAll in interface Multiset<E>

Overrides:

containsAll in class java.util.AbstractCollection<E>

Parameters:

targets - the collection of elements to be checked for containment in this multiset

Returns:

true if this multiset contains at least one occurrence of each element contained in elements

add

@Deprecated
public final int add(E element,
                     int occurrences)

Deprecated.

Unsupported operation.

Guaranteed to throw an exception and leave the collection unmodified.

Specified by:

add in interface Multiset<E>

Parameters:

element - the element to add occurrences of; may be null only if explicitly allowed by the implementation

occurrences - the number of occurrences of the element to add. May be zero, in which case no change will be made.

Returns:

the count of the element before the operation; possibly zero

Throws:

java.lang.UnsupportedOperationException - always

remove

@Deprecated
public final int remove(java.lang.Object element,
                        int occurrences)

Deprecated.

Unsupported operation.

Guaranteed to throw an exception and leave the collection unmodified.

Specified by:

remove in interface Multiset<E>

Parameters:

element - the element to conditionally remove occurrences of

occurrences - the number of occurrences of the element to remove. May be zero, in which case no change will be made.

Returns:

the count of the element before the operation; possibly zero

Throws:

java.lang.UnsupportedOperationException - always

setCount

@Deprecated
public final int setCount(E element,
                          int count)

Deprecated.

Unsupported operation.

Guaranteed to throw an exception and leave the collection unmodified.

Specified by:

setCount in interface Multiset<E>

Parameters:

element - the element to add or remove occurrences of; may be null only if explicitly allowed by the implementation

count - the desired count of the element in this multiset

Returns:

the count of the element before the operation; possibly zero

Throws:

java.lang.UnsupportedOperationException - always

setCount

@Deprecated
public final boolean setCount(E element,
                              int oldCount,
                              int newCount)

Deprecated.

Unsupported operation.

Guaranteed to throw an exception and leave the collection unmodified.

Specified by:

setCount in interface Multiset<E>

Parameters:

element - the element to conditionally set the count of; may be null only if explicitly allowed by the implementation

oldCount - the expected present count of the element in this multiset

newCount - the desired count of the element in this multiset

Returns:

true if the condition for modification was met. This implies that the multiset was indeed modified, unless oldCount == newCount.

Throws:

java.lang.UnsupportedOperationException - always

equals

public boolean equals(@Nullable
                      java.lang.Object object)

Description copied from interface: Multiset

Compares the specified object with this multiset for equality. Returns true if the given object is also a multiset and contains equal elements with equal counts, regardless of order.

Specified by:

equals in interface java.util.Collection<E>

Specified by:

equals in interface Multiset<E>

Overrides:

equals in class java.lang.Object

hashCode

public int hashCode()

Description copied from interface: Multiset

Returns the hash code for this multiset. This is defined as the sum of

    

   ((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.

Specified by:

hashCode in interface java.util.Collection<E>

Specified by:

hashCode in interface Multiset<E>

Overrides:

hashCode in class java.lang.Object

toString

public java.lang.String toString()

Description copied from interface: Multiset

It 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].

Specified by:

toString in interface Multiset<E>

Overrides:

toString in class java.util.AbstractCollection<E>

entrySet

public ImmutableSet<Multiset.Entry<E>> entrySet()

Description copied from interface: Multiset

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. 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.

Specified by:

entrySet in interface Multiset<E>

Returns:

a set of entries representing the data of this multiset

builder

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

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