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

Direct Known Subclasses:

ImmutableSortedMultiset

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

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

Grouped iteration. In all current implementations, duplicate elements always appear consecutively when iterating. Elements iterate in order by the first appearance of that element when the multiset was created.

See the Guava User Guide article on immutable collections.

Since:

2.0

Author:

Jared Levy, Louis Wasserman

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 extends @Nullable Object>

Method Summary

Modifier and Type	Method	Description
int	add(E element, int occurrences)	Deprecated. Unsupported operation.
ImmutableList<E>	asList()	Returns an ImmutableList containing the same elements, in the same order, as this collection.
static <E> ImmutableMultiset.Builder<E>	builder()	Returns a new builder.
boolean	contains(Object object)	Returns true if this collection contains the specified element.
static <E> ImmutableMultiset<E>	copyOf(E[] elements)	Returns an immutable multiset containing the given elements, in the "grouped iteration order" described in the class documentation.
static <E> ImmutableMultiset<E>	copyOf(Iterable<? extends E> elements)	Returns an immutable multiset containing the given elements, in the "grouped iteration order" described in the class documentation.
static <E> ImmutableMultiset<E>	copyOf(Iterator<? extends E> elements)	Returns an immutable multiset containing the given elements, in the "grouped iteration order" described in the class documentation.
abstract ImmutableSet<E>	elementSet()	Returns the set of distinct elements contained in this multiset.
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(Object object)	Indicates whether some other object is "equal to" this one.
int	hashCode()	Returns a hash code value for the object.
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 the "grouped iteration order" described in the class documentation.
static <E> ImmutableMultiset<E>	of(E e1, E e2, E e3, E e4)	Returns an immutable multiset containing the given elements, in the "grouped iteration order" described in the class documentation.
static <E> ImmutableMultiset<E>	of(E e1, E e2, E e3, E e4, E e5)	Returns an immutable multiset containing the given elements, in the "grouped iteration order" described in the class documentation.
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 the "grouped iteration order" described in the class documentation.
int	remove(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.
String	toString()	Returns a string representation of this collection.

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

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

Methods inherited from class java.util.AbstractCollection

containsAll, 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, spliterator, stream, toArray, toArray, toArray

Methods inherited from interface java.lang.Iterable

forEach

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

add, containsAll, count, remove, removeAll, retainAll, size

Method Detail

of

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

Returns the empty immutable multiset.

Performance note: the instance returned is a singleton.

of

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

Returns an immutable multiset containing a single element.

Throws:

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:

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 the "grouped iteration order" described in the class documentation.

Throws:

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 the "grouped iteration order" described in the class documentation.

Throws:

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 the "grouped iteration order" described in the class documentation.

Throws:

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 the "grouped iteration order" described in the class documentation.

Throws:

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, in the "grouped iteration order" described in the class documentation.

Throws:

NullPointerException - if any of elements is null

Since:

6.0

copyOf

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

Returns an immutable multiset containing the given elements, in the "grouped iteration order" described in the class documentation.

Throws:

NullPointerException - if any of elements is null

copyOf

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

Returns an immutable multiset containing the given elements, in the "grouped iteration order" described in the class documentation.

Throws:

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 Collection<E>

Specified by:

iterator in interface Iterable<E>

Specified by:

iterator in interface Multiset<E>

Specified by:

iterator in class ImmutableCollection<E>

Returns:

an iterator over the elements contained in this collection

asList

public ImmutableList<E> asList()

Description copied from class: ImmutableCollection

Returns an ImmutableList containing the same elements, in the same order, as this collection.

Performance note: in most cases this method can return quickly without actually copying anything. The exact circumstances under which the copy is performed are undefined and subject to change.

Overrides:

asList in class ImmutableCollection<E>

contains

public boolean contains(@CheckForNull
                        Object object)

Description copied from class: java.util.AbstractCollection

Returns true if this collection contains the specified element. More formally, returns true if and only if this collection contains at least one element e such that Objects.equals(o, e).

Specified by:

contains in interface Collection<E>

Specified by:

contains in interface Multiset<E>

Specified by:

contains in class ImmutableCollection<E>

Parameters:

object - element whose presence in this collection is to be tested

Returns:

true if this collection contains the specified element

add

@CanIgnoreReturnValue
@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:

UnsupportedOperationException - always

remove

@CanIgnoreReturnValue
@Deprecated
public final int remove(@CheckForNull
                        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:

UnsupportedOperationException - always

setCount

@CanIgnoreReturnValue
@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:

UnsupportedOperationException - always

setCount

@CanIgnoreReturnValue
@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:

UnsupportedOperationException - always

equals

public boolean equals(@CheckForNull
                      Object object)

Description copied from class: java.lang.Object

Indicates whether some other object is "equal to" this one.

The equals method implements an equivalence relation on non-null object references:

• It is reflexive: for any non-null reference value x, x.equals(x) should return true.
• It is symmetric: for any non-null reference values x and y, x.equals(y) should return true if and only if y.equals(x) returns true.
• It is transitive: for any non-null reference values x, y, and z, if x.equals(y) returns true and y.equals(z) returns true, then x.equals(z) should return true.
• It is consistent: for any non-null reference values x and y, multiple invocations of x.equals(y) consistently return true or consistently return false, provided no information used in equals comparisons on the objects is modified.
• For any non-null reference value x, x.equals(null) should return false.

The equals method for class Object implements the most discriminating possible equivalence relation on objects; that is, for any non-null reference values x and y, this method returns true if and only if x and y refer to the same object (x == y has the value true).

Note that it is generally necessary to override the hashCode method whenever this method is overridden, so as to maintain the general contract for the hashCode method, which states that equal objects must have equal hash codes.

Specified by:

equals in interface Collection<E>

Specified by:

equals in interface Multiset<E>

Overrides:

equals in class Object

Parameters:

object - the reference object with which to compare.

Returns:

true if this object is the same as the obj argument; false otherwise.

See Also:

Object.hashCode(), HashMap

hashCode

public int hashCode()

Description copied from class: java.lang.Object

Returns a hash code value for the object. This method is supported for the benefit of hash tables such as those provided by HashMap.

The general contract of hashCode is:

• Whenever it is invoked on the same object more than once during an execution of a Java application, the hashCode method must consistently return the same integer, provided no information used in equals comparisons on the object is modified. This integer need not remain consistent from one execution of an application to another execution of the same application.
• If two objects are equal according to the equals(Object) method, then calling the hashCode method on each of the two objects must produce the same integer result.
• It is not required that if two objects are unequal according to the Object.equals(java.lang.Object) method, then calling the hashCode method on each of the two objects must produce distinct integer results. However, the programmer should be aware that producing distinct integer results for unequal objects may improve the performance of hash tables.

As much as is reasonably practical, the hashCode method defined by class Object does return distinct integers for distinct objects. (The hashCode may or may not be implemented as some function of an object's memory address at some point in time.)

Specified by:

hashCode in interface Collection<E>

Specified by:

hashCode in interface Multiset<E>

Overrides:

hashCode in class Object

Returns:

a hash code value for this object.

See Also:

Object.equals(java.lang.Object), System.identityHashCode(java.lang.Object)

toString

public String toString()

Description copied from class: java.util.AbstractCollection

Returns a string representation of this collection. The string representation consists of a list of the collection's elements in the order they are returned by its iterator, enclosed in square brackets ("[]"). Adjacent elements are separated by the characters ", " (comma and space). Elements are converted to strings as by String.valueOf(Object).

Specified by:

toString in interface Multiset<E>

Overrides:

toString in class AbstractCollection<E>

Returns:

a string representation of this collection

elementSet

public abstract ImmutableSet<E> elementSet()

Description copied from interface: Multiset

Returns the set of distinct elements contained in this multiset. The element set is backed by the same data as the multiset, so any change to either is immediately reflected in the other. The order of the elements in the element set is unspecified.

If 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().

Specified by:

elementSet in interface Multiset<E>

Returns:

a view of the set of distinct elements in this multiset

Since:

21.0 (present with return type Set since 2.0)

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.