Class EnumMultiset<E extends Enum<E>>

All Implemented Interfaces:
Multiset<E>, Serializable, Iterable<E>, Collection<E>

public final class EnumMultiset<E extends Enum<E>> extends AbstractMultiset<E> implements Serializable
Multiset implementation specialized for enum elements, supporting all single-element operations in O(1).

See the Guava User Guide article on Multiset.

Since:
2.0
See Also:
  • Field Details

    • type

      private transient Class<E extends Enum<E>> type
    • enumConstants

      private transient E extends Enum<E>[] enumConstants
    • counts

      private transient int[] counts
    • distinctElements

      private transient int distinctElements
    • size

      private transient long size
    • serialVersionUID

      private static final long serialVersionUID
      See Also:
  • Constructor Details

    • EnumMultiset

      private EnumMultiset(Class<E> type)
      Creates an empty EnumMultiset.
  • Method Details

    • create

      public static <E extends Enum<E>> EnumMultiset<E> create(Class<E> type)
      Creates an empty EnumMultiset.
    • create

      public static <E extends Enum<E>> EnumMultiset<E> create(Iterable<E> elements)
      Creates a new EnumMultiset containing the specified elements.

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

      Parameters:
      elements - the elements that the multiset should contain
      Throws:
      IllegalArgumentException - if elements is empty
    • create

      public static <E extends Enum<E>> EnumMultiset<E> create(Iterable<E> elements, Class<E> type)
      Returns a new EnumMultiset instance containing the given elements. Unlike create(Iterable), this method does not produce an exception on an empty iterable.
      Since:
      14.0
    • isActuallyE

      private boolean isActuallyE(@CheckForNull Object o)
    • checkIsE

      private void checkIsE(Object element)
      Returns element cast to E, if it actually is a nonnull E. Otherwise, throws either a NullPointerException or a ClassCastException as appropriate.
    • distinctElements

      int distinctElements()
      Specified by:
      distinctElements in class AbstractMultiset<E extends Enum<E>>
    • 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 Collection<E extends Enum<E>>
      Specified by:
      size in interface Multiset<E extends Enum<E>>
      Specified by:
      size in class AbstractCollection<E extends Enum<E>>
    • count

      public int count(@CheckForNull 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 Enum<E>>
      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

      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 Enum<E>>
      Overrides:
      add in class AbstractMultiset<E extends Enum<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
    • remove

      public int remove(@CheckForNull 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 Enum<E>>
      Overrides:
      remove in class AbstractMultiset<E extends Enum<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
    • setCount

      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 Enum<E>>
      Overrides:
      setCount in class AbstractMultiset<E extends Enum<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
    • clear

      public void clear()
      Specified by:
      clear in interface Collection<E extends Enum<E>>
      Specified by:
      clear in class AbstractMultiset<E extends Enum<E>>
    • elementIterator

      Iterator<E> elementIterator()
      Specified by:
      elementIterator in class AbstractMultiset<E extends Enum<E>>
    • entryIterator

      Iterator<Multiset.Entry<E>> entryIterator()
      Specified by:
      entryIterator in class AbstractMultiset<E extends Enum<E>>
    • forEachEntry

      public void forEachEntry(ObjIntConsumer<? super E> action)
      Description copied from interface: Multiset
      Runs the specified action for each distinct element in this multiset, and the number of occurrences of that element. For some Multiset implementations, this may be more efficient than iterating over the Multiset.entrySet() either explicitly or with entrySet().forEach(action).
      Specified by:
      forEachEntry in interface Multiset<E extends Enum<E>>
    • iterator

      public Iterator<E> iterator()
      Description copied from interface: Multiset

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

      Specified by:
      iterator in interface Collection<E extends Enum<E>>
      Specified by:
      iterator in interface Iterable<E extends Enum<E>>
      Specified by:
      iterator in interface Multiset<E extends Enum<E>>
      Specified by:
      iterator in class AbstractCollection<E extends Enum<E>>
    • writeObject

      private void writeObject(ObjectOutputStream stream) throws IOException
      Throws:
      IOException
    • readObject

      private void readObject(ObjectInputStream stream) throws IOException, ClassNotFoundException
      Throws:
      IOException
      ClassNotFoundException