Package com.google.common.collect

Class TreeMultiset<E extends @Nullable java.lang.Object>

  • All Implemented Interfaces:
    Multiset<E>, SortedMultiset<E>, java.io.Serializable, java.lang.Iterable<E>, java.util.Collection<E>
    @GwtCompatible(emulated=true)
public final class TreeMultiset<E extends @Nullable java.lang.Object>
extends java.util.AbstractCollection<E>
implements java.io.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.

    Since:
    2.0
    Author:
    Louis Wasserman, Jared Levy
    See Also:
    Serialized Form

    • Method Summary

      All Methods Static Methods Instance Methods Concrete Methods 
      Modifier and Type Method 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​(java.util.Collection<? extends E> elementsToAdd)
      void clear()  
      java.util.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​(java.lang.Object element)
      Determines whether this multiset contains the specified element.
      int count​(java.lang.Object element)
      Returns the number of occurrences of an element in this multiset (the count of the element).
      static <E extends java.lang.Comparable>
      TreeMultiset<E>      		 create()
      Creates a new, empty multiset, sorted according to the elements' natural order.
      static <E extends java.lang.Comparable>
      TreeMultiset<E>      		 create​(java.lang.Iterable<? extends E> elements)
      Creates an empty multiset containing the given initial elements, sorted according to the elements' natural order.
      static <E extends @Nullable java.lang.Object>
      TreeMultiset<E>      		 create​(java.util.Comparator<? super E> comparator)
      Creates a new, empty multiset, sorted according to the specified comparator.
      SortedMultiset<E> descendingMultiset()
      Returns a descending view of this multiset.
      java.util.NavigableSet<E> elementSet()
      Returns the set of distinct elements contained in this multiset.
      java.util.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​(java.lang.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()  
      java.util.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​(java.lang.Object element)
      Removes a single occurrence of the specified element from this multiset, if present.
      int remove​(java.lang.Object element, int occurrences)
      Removes a number of occurrences of the specified element from this multiset.
      boolean removeAll​(java.util.Collection<?> elementsToRemove)
      boolean retainAll​(java.util.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()
      Returns the total number of all occurrences of all elements in this multiset.
      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.
      java.lang.String toString()

      • Methods inherited from class java.util.AbstractCollection

        containsAll, toArray, toArray

      • Methods inherited from class java.lang.Object

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

      • Methods inherited from interface java.util.Collection

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

      • Methods inherited from interface java.lang.Iterable

        forEach

    • Method Detail

      • create

        public static <E extends java.lang.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.

      • create

        public static <E extends @Nullable java.lang.Object> TreeMultiset<E> create​(@CheckForNull
                                                                            java.util.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.
        Parameters:
        comparator - the comparator that will be used to sort this multiset. A null value indicates that the elements' natural ordering should be used.

      • create

        public static <E extends java.lang.Comparable> TreeMultiset<E> create​(java.lang.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.

      • size

        public int size()
        Description copied from interface: Multiset
        Returns the total number of all occurrences of all elements in this multiset.

        Note: this method does not return the number of distinct elements in the multiset, which is given by entrySet().size().

        Specified by:
        size in interface java.util.Collection<E extends @Nullable java.lang.Object>
        Specified by:
        size in interface Multiset<E extends @Nullable java.lang.Object>
        Specified by:
        size in class java.util.AbstractCollection<E extends @Nullable java.lang.Object>

      • count

        public int count​(@CheckForNull
                 java.lang.Object element)
        Description copied from interface: Multiset
        Returns 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.

        Specified by:
        count in interface Multiset<E extends @Nullable java.lang.Object>
        Parameters:
        element - the element to count occurrences of
        Returns:
        the number of occurrences of the element in this multiset; possibly zero but never negative

      • add

        @CanIgnoreReturnValue
public int add​(E element,
               int occurrences)
        Description copied from interface: Multiset
        Adds 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.
        Specified by:
        add in interface Multiset<E extends @Nullable java.lang.Object>
        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

      • remove

        @CanIgnoreReturnValue
public int remove​(@CheckForNull
                  java.lang.Object element,
                  int occurrences)
        Description copied from interface: Multiset
        Removes 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).
        Specified by:
        remove in interface Multiset<E extends @Nullable java.lang.Object>
        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

      • setCount

        @CanIgnoreReturnValue
public int setCount​(E element,
                    int count)
        Description copied from interface: Multiset
        Adds or removes the necessary occurrences of an element such that the element attains the desired count.
        Specified by:
        setCount in interface Multiset<E extends @Nullable java.lang.Object>
        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

      • setCount

        @CanIgnoreReturnValue
public boolean setCount​(E element,
                        int oldCount,
                        int newCount)
        Description copied from interface: Multiset
        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. If the current count is not oldCount, no change is made.
        Specified by:
        setCount in interface Multiset<E extends @Nullable java.lang.Object>
        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.

      • clear

        public void clear()
        Specified by:
        clear in interface java.util.Collection<E extends @Nullable java.lang.Object>

      • iterator

        public java.util.Iterator<E> iterator()
        Description copied from interface: SortedMultiset

        Elements that occur multiple times in the multiset will appear multiple times in this iterator, though not necessarily sequentially.

        The iterator returns the elements in ascending order according to this multiset's comparator.

        Specified by:
        iterator in interface java.util.Collection<E extends @Nullable java.lang.Object>
        Specified by:
        iterator in interface java.lang.Iterable<E extends @Nullable java.lang.Object>
        Specified by:
        iterator in interface Multiset<E extends @Nullable java.lang.Object>
        Specified by:
        iterator in interface SortedMultiset<E extends @Nullable java.lang.Object>
        Specified by:
        iterator in class java.util.AbstractCollection<E extends @Nullable java.lang.Object>

      • headMultiset

        public SortedMultiset<E> headMultiset​(E upperBound,
                                      BoundType boundType)
        Description copied from interface: SortedMultiset
        Returns 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.

        Specified by:
        headMultiset in interface SortedMultiset<E extends @Nullable java.lang.Object>

      • tailMultiset

        public SortedMultiset<E> tailMultiset​(E lowerBound,
                                      BoundType boundType)
        Description copied from interface: SortedMultiset
        Returns 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.

        Specified by:
        tailMultiset in interface SortedMultiset<E extends @Nullable java.lang.Object>

      • elementSet

        public java.util.NavigableSet<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 extends @Nullable java.lang.Object>
        Specified by:
        elementSet in interface SortedMultiset<E extends @Nullable java.lang.Object>
        Returns:
        a view of the set of distinct elements in this multiset

      • comparator

        public java.util.Comparator<? super E> comparator()
        Description copied from interface: SortedMultiset
        Returns the comparator that orders this multiset, or Ordering.natural() if the natural ordering of the elements is used.
        Specified by:
        comparator in interface SortedMultiset<E extends @Nullable java.lang.Object>

      • subMultiset

        public SortedMultiset<E> subMultiset​(E fromElement,
                                     BoundType fromBoundType,
                                     E toElement,
                                     BoundType toBoundType)
        Description copied from interface: SortedMultiset
        Returns 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).

        Specified by:
        subMultiset in interface SortedMultiset<E extends @Nullable java.lang.Object>

      • isEmpty

        public boolean isEmpty()
        Specified by:
        isEmpty in interface java.util.Collection<E extends @Nullable java.lang.Object>
        Overrides:
        isEmpty in class java.util.AbstractCollection<E extends @Nullable java.lang.Object>

      • contains

        public boolean contains​(@CheckForNull
                        java.lang.Object element)
        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 extends @Nullable java.lang.Object>
        Specified by:
        contains in interface Multiset<E extends @Nullable java.lang.Object>
        Overrides:
        contains in class java.util.AbstractCollection<E extends @Nullable java.lang.Object>
        Parameters:
        element - the element to check for
        Returns:
        true if this multiset contains at least one occurrence of the element

      • add

        @CanIgnoreReturnValue
public final boolean add​(E element)
        Description copied from interface: Multiset
        Adds 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.

        Specified by:
        add in interface java.util.Collection<E extends @Nullable java.lang.Object>
        Specified by:
        add in interface Multiset<E extends @Nullable java.lang.Object>
        Overrides:
        add in class java.util.AbstractCollection<E extends @Nullable java.lang.Object>
        Parameters:
        element - the element to add one occurrence of; may be null only if explicitly allowed by the implementation
        Returns:
        true always, since this call is required to modify the multiset, unlike other Collection types

      • remove

        @CanIgnoreReturnValue
public final boolean remove​(@CheckForNull
                            java.lang.Object element)
        Description copied from interface: Multiset
        Removes 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.

        Specified by:
        remove in interface java.util.Collection<E extends @Nullable java.lang.Object>
        Specified by:
        remove in interface Multiset<E extends @Nullable java.lang.Object>
        Overrides:
        remove in class java.util.AbstractCollection<E extends @Nullable java.lang.Object>
        Parameters:
        element - the element to remove one occurrence of
        Returns:
        true if an occurrence was found and removed

      • addAll

        @CanIgnoreReturnValue
public final boolean addAll​(java.util.Collection<? extends E> elementsToAdd)

        This implementation is highly efficient when elementsToAdd is itself a Multiset.

        Specified by:
        addAll in interface java.util.Collection<E extends @Nullable java.lang.Object>
        Overrides:
        addAll in class java.util.AbstractCollection<E extends @Nullable java.lang.Object>

      • removeAll

        @CanIgnoreReturnValue
public final boolean removeAll​(java.util.Collection<?> elementsToRemove)
        Description copied from interface: Multiset

        Note: 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.

        Specified by:
        removeAll in interface java.util.Collection<E extends @Nullable java.lang.Object>
        Specified by:
        removeAll in interface Multiset<E extends @Nullable java.lang.Object>
        Overrides:
        removeAll in class java.util.AbstractCollection<E extends @Nullable java.lang.Object>

      • retainAll

        @CanIgnoreReturnValue
public final boolean retainAll​(java.util.Collection<?> elementsToRetain)
        Description copied from interface: Multiset

        Note: 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.

        Specified by:
        retainAll in interface java.util.Collection<E extends @Nullable java.lang.Object>
        Specified by:
        retainAll in interface Multiset<E extends @Nullable java.lang.Object>
        Overrides:
        retainAll in class java.util.AbstractCollection<E extends @Nullable java.lang.Object>
        See Also:
        Multisets.retainOccurrences(Multiset, Multiset)

      • entrySet

        public java.util.Set<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 extends @Nullable java.lang.Object>
        Returns:
        a set of entries representing the data of this multiset

      • equals

        public final boolean equals​(@CheckForNull
                            java.lang.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.

        Specified by:
        equals in interface java.util.Collection<E extends @Nullable java.lang.Object>
        Specified by:
        equals in interface Multiset<E extends @Nullable java.lang.Object>
        Overrides:
        equals in class java.lang.Object

      • hashCode

        public final 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().

        Specified by:
        hashCode in interface java.util.Collection<E extends @Nullable java.lang.Object>
        Specified by:
        hashCode in interface Multiset<E extends @Nullable java.lang.Object>
        Overrides:
        hashCode in class java.lang.Object

      • toString

        public final java.lang.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().

        Specified by:
        toString in interface Multiset<E extends @Nullable java.lang.Object>
        Overrides:
        toString in class java.util.AbstractCollection<E extends @Nullable java.lang.Object>