@GwtCompatible(emulated=true) public final class TreeMultiset<E> extends AbstractCollection<E> implements Serializable
A multiset which maintains the ordering of its elements, according to either their natural order or an explicit Comparator. In all cases, this implementation uses Comparable.compareTo(T) or Comparator.compare(T, T) instead of Object.equals(java.lang.Object) to determine equivalence of instances.
Warning: The comparison must be consistent with equals as explained by the Comparable class specification. Otherwise, the resulting multiset will violate the Collection contract, which is specified in terms of Object.equals(java.lang.Object).
See the Guava User Guide article on Multiset.
Multiset.Entry<E>| Modifier and Type | Method and Description |
|---|---|
boolean |
add(E element)
Adds a single occurrence of the specified element to this multiset.
|
int |
add(E element,
int occurrences)
Adds a number of occurrences of an element to this multiset.
|
boolean |
addAll(Collection<? extends E> elementsToAdd) |
void |
clear() |
Comparator<? super E> |
comparator()
Returns the comparator that orders this multiset, or
Ordering.natural() if the natural ordering of the elements is used. |
boolean |
contains(Object element)
Determines whether this multiset contains the specified element.
|
int |
count(Object element)
Returns the number of occurrences of an element in this multiset (the count of the element).
|
static <E extends Comparable> |
create()
Creates a new, empty multiset, sorted according to the elements’ natural order.
|
static <E> TreeMultiset<E> |
create(Comparator<? super E> comparator)
Creates a new, empty multiset, sorted according to the specified comparator.
|
static <E extends Comparable> |
create(Iterable<? extends E> elements)
Creates an empty multiset containing the given initial elements, sorted according to the elements’ natural order.
|
SortedMultiset<E> |
descendingMultiset()
Returns a descending view of this multiset.
|
NavigableSet<E> |
elementSet()
Returns the set of distinct elements contained in this multiset.
|
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. |
boolean |
equals(Object object)
Compares the specified object with this multiset for equality.
|
Multiset.Entry<E> |
firstEntry()
Returns the entry of the first element in this multiset, or
null if this multiset is empty. |
int |
hashCode()
Returns the hash code for this multiset.
|
SortedMultiset<E> |
headMultiset(E upperBound,
BoundType boundType)
Returns a view of this multiset restricted to the elements less than
upperBound, optionally including upperBound itself. |
boolean |
isEmpty() |
Iterator<E> |
iterator() |
Multiset.Entry<E> |
lastEntry()
Returns the entry of the last element in this multiset, or
null if this multiset is empty. |
Multiset.Entry<E> |
pollFirstEntry()
Returns and removes the entry associated with the lowest element in this multiset, or returns
null if this multiset is empty. |
Multiset.Entry<E> |
pollLastEntry()
Returns and removes the entry associated with the greatest element in this multiset, or returns
null if this multiset is empty. |
boolean |
remove(Object element)
Removes a single occurrence of the specified element from this multiset, if present.
|
int |
remove(Object element,
int occurrences)
Removes a number of occurrences of the specified element from this multiset.
|
boolean |
removeAll(Collection<?> elementsToRemove) |
boolean |
retainAll(Collection<?> elementsToRetain) |
int |
setCount(E element,
int count)
Adds or removes the necessary occurrences of an element such that the element attains the desired count.
|
boolean |
setCount(E element,
int oldCount,
int newCount)
Conditionally sets the count of an element to a new value, as described in
Multiset.setCount(Object, int), provided that the element has the expected current count. |
int |
size() |
SortedMultiset<E> |
subMultiset(E fromElement,
BoundType fromBoundType,
E toElement,
BoundType toBoundType)
Returns a view of this multiset restricted to the range between
lowerBound and upperBound. |
SortedMultiset<E> |
tailMultiset(E lowerBound,
BoundType boundType)
Returns a view of this multiset restricted to the elements greater than
lowerBound, optionally including lowerBound itself. |
String |
toString() |
containsAll, toArray, toArrayclone, finalize, getClass, notify, notifyAll, wait, wait, waitentrySet, iteratoradd, contains, containsAll, equals, hashCode, remove, removeAll, retainAll, toStringaddAll, clear, isEmpty, parallelStream, removeIf, spliterator, stream, toArray, toArraypublic static <E extends Comparable> TreeMultiset<E> create()
Creates a new, empty multiset, sorted according to the elements’ natural order. All elements inserted into the multiset must implement the Comparable interface. Furthermore, all such elements must be mutually comparable: e1.compareTo(e2) must not throw a ClassCastException for any elements e1 and e2 in the multiset. If the user attempts to add an element to the multiset that violates this constraint (for example, the user attempts to add a string element to a set whose elements are integers), the add(Object) call will throw a ClassCastException.
The type specification is <E extends Comparable>, instead of the more specific <E extends Comparable<? super E>>, to support classes defined without generics.
public static <E> TreeMultiset<E> create(@Nullable Comparator<? super E> comparator)
Creates a new, empty multiset, sorted according to the specified comparator. All elements inserted into the multiset must be mutually comparable by the specified comparator: comparator.compare(e1,
e2) must not throw a ClassCastException for any elements e1 and e2 in the multiset. If the user attempts to add an element to the multiset that violates this constraint, the add(Object) call will throw a ClassCastException.
comparator - the comparator that will be used to sort this multiset. A null value indicates that the elements’ natural ordering should be used.public static <E extends Comparable> TreeMultiset<E> create(Iterable<? extends E> elements)
Creates an empty multiset containing the given initial elements, sorted according to the elements’ natural order.
This implementation is highly efficient when elements is itself a Multiset.
The type specification is <E extends Comparable>, instead of the more specific <E extends Comparable<? super E>>, to support classes defined without generics.
public int size()
size in interface Collection<E>public int count(@Nullable Object element)
MultisetReturns the number of occurrences of an element in this multiset (the count of the element). Note that for an Object.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.
public int add(@Nullable E element, int occurrences)
MultisetAdds a number of occurrences of an element to this multiset. Note that if occurrences == 1, this method has the identical effect to Multiset.add(Object). This method is functionally equivalent (except in the case of overflow) to the call addAll(Collections.nCopies(element,
occurrences)), which would presumably perform much more poorly.
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.public int remove(@Nullable Object element, int occurrences)
MultisetRemoves a number of occurrences of the specified element from this multiset. If the multiset contains fewer than this number of occurrences to begin with, all occurrences will be removed. Note that if occurrences == 1, this is functionally equivalent to the call remove(element).
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.public int setCount(@Nullable E element, int count)
MultisetAdds or removes the necessary occurrences of an element such that the element attains the desired 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 multisetpublic boolean setCount(@Nullable E element, int oldCount, int newCount)
MultisetConditionally sets the count of an element to a new value, as described in Multiset.setCount(Object, int), provided that the element has the expected current count. If the current count is not oldCount, no change is made.
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 multisettrue if the condition for modification was met. This implies that the multiset was indeed modified, unless oldCount == newCount.public SortedMultiset<E> headMultiset(@Nullable E upperBound, BoundType boundType)
SortedMultisetReturns a view of this multiset restricted to the elements less than upperBound, optionally including upperBound itself. The returned multiset is a view of this multiset, so changes to one will be reflected in the other. The returned multiset supports all operations that this multiset supports.
The returned multiset will throw an IllegalArgumentException on attempts to add elements outside its range.
headMultiset in interface SortedMultiset<E>public SortedMultiset<E> tailMultiset(@Nullable E lowerBound, BoundType boundType)
SortedMultisetReturns a view of this multiset restricted to the elements greater than lowerBound, optionally including lowerBound itself. The returned multiset is a view of this multiset, so changes to one will be reflected in the other. The returned multiset supports all operations that this multiset supports.
The returned multiset will throw an IllegalArgumentException on attempts to add elements outside its range.
tailMultiset in interface SortedMultiset<E>public NavigableSet<E> elementSet()
MultisetReturns 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().
elementSet in interface Multiset<E>elementSet in interface SortedMultiset<E>public Comparator<? super E> comparator()
SortedMultisetReturns the comparator that orders this multiset, or Ordering.natural() if the natural ordering of the elements is used.
comparator in interface SortedMultiset<E>public Multiset.Entry<E> firstEntry()
SortedMultisetReturns the entry of the first element in this multiset, or null if this multiset is empty.
firstEntry in interface SortedMultiset<E>public Multiset.Entry<E> lastEntry()
SortedMultisetReturns the entry of the last element in this multiset, or null if this multiset is empty.
lastEntry in interface SortedMultiset<E>public Multiset.Entry<E> pollFirstEntry()
SortedMultisetReturns and removes the entry associated with the lowest element in this multiset, or returns null if this multiset is empty.
pollFirstEntry in interface SortedMultiset<E>public Multiset.Entry<E> pollLastEntry()
SortedMultisetReturns and removes the entry associated with the greatest element in this multiset, or returns null if this multiset is empty.
pollLastEntry in interface SortedMultiset<E>public SortedMultiset<E> subMultiset(@Nullable E fromElement, BoundType fromBoundType, @Nullable E toElement, BoundType toBoundType)
SortedMultisetReturns a view of this multiset restricted to the range between lowerBound and upperBound. The returned multiset is a view of this multiset, so changes to one will be reflected in the other. The returned multiset supports all operations that this multiset supports.
The returned multiset will throw an IllegalArgumentException on attempts to add elements outside its range.
This method is equivalent to tailMultiset(lowerBound, lowerBoundType).headMultiset(upperBound,
upperBoundType).
subMultiset in interface SortedMultiset<E>public SortedMultiset<E> descendingMultiset()
SortedMultisetReturns a descending view of this multiset. Modifications made to either map will be reflected in the other.
descendingMultiset in interface SortedMultiset<E>public boolean isEmpty()
isEmpty in interface Collection<E>isEmpty in class AbstractCollection<E>public boolean contains(@Nullable Object element)
MultisetDetermines 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.
contains in interface Multiset<E>contains in interface Collection<E>contains in class AbstractCollection<E>element - the element to check fortrue if this multiset contains at least one occurrence of the elementpublic Iterator<E> iterator()
MultisetElements that occur multiple times in the multiset will appear multiple times in this iterator, though not necessarily sequentially.
public boolean add(@Nullable E element)
MultisetAdds a single occurrence of the specified element to this multiset.
This method refines Collection.add(E), which only ensures the presence of the element, to further specify that a successful call must always increment the count of the element, and the overall size of the collection, by one.
To both add the element and obtain the previous count of that element, use add(element, 1) instead.
add in interface Multiset<E>add in interface Collection<E>add in class AbstractCollection<E>element - the element to add one occurrence of; may be null only if explicitly allowed by the implementationtrue always, since this call is required to modify the multiset, unlike other Collection typespublic boolean remove(@Nullable Object element)
MultisetRemoves a single occurrence of the specified element from this multiset, if present.
This method refines Collection.remove(java.lang.Object) to further specify that it may not throw an exception in response to element being null or of the wrong type.
To both remove the element and obtain the previous count of that element, use remove(element, 1) instead.
remove in interface Multiset<E>remove in interface Collection<E>remove in class AbstractCollection<E>element - the element to remove one occurrence oftrue if an occurrence was found and removedpublic boolean addAll(Collection<? extends E> elementsToAdd)
This implementation is highly efficient when elementsToAdd
is itself a Multiset.
addAll in interface Collection<E>addAll in class AbstractCollection<E>public boolean removeAll(Collection<?> elementsToRemove)
MultisetNote: This method ignores how often any element might appear in c, and only cares whether or not an element appears at all. If you wish to remove one occurrence in this multiset for every occurrence in c, see Multisets.removeOccurrences(Multiset, Multiset).
This method refines Collection.removeAll(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.
removeAll in interface Multiset<E>removeAll in interface Collection<E>removeAll in class AbstractCollection<E>public boolean retainAll(Collection<?> elementsToRetain)
MultisetNote: This method ignores how often any element might appear in c, and only cares whether or not an element appears at all. If you wish to remove one occurrence in this multiset for every occurrence in c, see Multisets.retainOccurrences(Multiset, Multiset).
This method refines Collection.retainAll(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.
retainAll in interface Multiset<E>retainAll in interface Collection<E>retainAll in class AbstractCollection<E>Multisets.retainOccurrences(Multiset, Multiset)public void clear()
clear in interface Collection<E>clear in class AbstractCollection<E>public Set<Multiset.Entry<E>> entrySet()
MultisetReturns 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.
public boolean equals(@Nullable Object object)
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.
This implementation returns true if object is a multiset
of the same size and if, for each element, the two multisets have the same
count.
public int hashCode()
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.
This implementation returns the hash code of Multiset.entrySet().
public String toString()
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].
This implementation returns the result of invoking toString on
Multiset.entrySet().