Class AbstractMapBasedMultiset<E>

java.lang.Object
java.util.AbstractCollection<E>
com.google.common.collect.AbstractMultiset<E>
com.google.common.collect.AbstractMapBasedMultiset<E>
All Implemented Interfaces:
Multiset<E>, Serializable, Iterable<E>, Collection<E>
Direct Known Subclasses:
HashMultiset, LinkedHashMultiset

abstract class AbstractMapBasedMultiset<E> extends AbstractMultiset<E> implements Serializable
Basic implementation of Multiset<E> backed by an instance of Map<E, Count>.

For serialization to work, the subclass must specify explicit readObject and writeObject methods.

  • Field Details

    • backingMap

      private transient Map<E,Count> backingMap
    • size

      private transient long size
    • serialVersionUID

      private static final long serialVersionUID
      See Also:
  • Constructor Details

    • AbstractMapBasedMultiset

      protected AbstractMapBasedMultiset(Map<E,Count> backingMap)
      Standard constructor.
  • Method Details

    • setBackingMap

      void setBackingMap(Map<E,Count> backingMap)
      Used during deserialization only. The backing map must be empty.
    • entrySet

      public 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. 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.

      Invoking Multiset.Entry.getCount() on an entry in the returned set always returns the current count of that element in the multiset, as opposed to the count at the time the entry was retrieved.

      Specified by:
      entrySet in interface Multiset<E>
      Overrides:
      entrySet in class AbstractMultiset<E>
      Returns:
      a set of entries representing the data of this multiset
    • elementIterator

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

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

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

      int distinctElements()
      Specified by:
      distinctElements in class AbstractMultiset<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>
      Specified by:
      size in interface Multiset<E>
      Specified by:
      size in class AbstractCollection<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>
      Specified by:
      iterator in interface Iterable<E>
      Specified by:
      iterator in interface Multiset<E>
      Specified by:
      iterator in class AbstractCollection<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>
      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)
      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>
      Overrides:
      add in class AbstractMultiset<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:
      IllegalArgumentException - if the call would result in more than Integer.MAX_VALUE occurrences of element in this multiset.
    • 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>
      Overrides:
      remove in class AbstractMultiset<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>
      Overrides:
      setCount in class AbstractMultiset<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
    • getAndSet

      private static int getAndSet(@CheckForNull Count i, int count)
    • readObjectNoData

      private void readObjectNoData() throws ObjectStreamException
      Throws:
      ObjectStreamException