Package org.apache.commons.collections4.multiset

Class AbstractMultiSet<E>

  • Type Parameters:
    E - the type held in the multiset
    All Implemented Interfaces:
    java.lang.Iterable<E>, java.util.Collection<E>, MultiSet<E>
    Direct Known Subclasses:
    AbstractMapMultiSet
    public abstract class AbstractMultiSet<E>
extends java.util.AbstractCollection<E>
implements MultiSet<E>
    Abstract implementation of the MultiSet interface to simplify the creation of subclass implementations.
    Since:
    4.1

    • Nested Class Summary

    • Method Summary

      All Methods Instance Methods Concrete Methods 
      Modifier and Type Method Description
      boolean add​(E object)
      Adds one copy of the specified object to the MultiSet.
      int add​(E object, int occurrences)
      Adds a number of occurrences of the specified object to the MultiSet.
      void clear()
      Clears the multiset removing all elements from the entrySet.
      boolean contains​(java.lang.Object object)
      Determines if the multiset contains the given element.
      java.util.Set<MultiSet.Entry<E>> entrySet()
      Returns an unmodifiable view of the entries of this multiset.
      boolean equals​(java.lang.Object object)
      Compares this MultiSet to another object.
      int getCount​(java.lang.Object object)
      Returns the number of occurrence of the given element in this multiset by iterating over its entrySet.
      int hashCode()
      Gets a hash code for the MultiSet compatible with the definition of equals.
      java.util.Iterator<E> iterator()
      Gets an iterator over the multiset elements.
      boolean remove​(java.lang.Object object)
      Removes one occurrence of the given object from the MultiSet.
      int remove​(java.lang.Object object, int occurrences)
      Removes a number of occurrences of the specified object from the MultiSet.
      boolean removeAll​(java.util.Collection<?> coll)
      Remove all occurrences of all elements from this MultiSet represented in the given collection.
      int setCount​(E object, int count)
      Sets the number of occurrences of the specified object in the MultiSet to the given count.
      int size()
      Returns the number of elements in this multiset.
      java.lang.String toString()
      Implement a toString() method suitable for debugging.
      java.util.Set<E> uniqueSet()
      Returns a view of the unique elements of this multiset.

      • Methods inherited from class java.util.AbstractCollection

        addAll, containsAll, isEmpty, retainAll, toArray, toArray

      • Methods inherited from class java.lang.Object

        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

      • size

        public int size()
        Returns the number of elements in this multiset.
        Specified by:
        size in interface java.util.Collection<E>
        Specified by:
        size in interface MultiSet<E>
        Specified by:
        size in class java.util.AbstractCollection<E>
        Returns:
        current size of the multiset

      • getCount

        public int getCount​(java.lang.Object object)
        Returns the number of occurrence of the given element in this multiset by iterating over its entrySet.
        Specified by:
        getCount in interface MultiSet<E>
        Parameters:
        object - the object to search for
        Returns:
        the number of occurrences of the object, zero if not found

      • setCount

        public int setCount​(E object,
                    int count)
        Description copied from interface: MultiSet
        Sets the number of occurrences of the specified object in the MultiSet to the given count.

        If the provided count is zero, the object will be removed from the MultiSet.uniqueSet().

        Specified by:
        setCount in interface MultiSet<E>
        Parameters:
        object - the object to update
        count - the number of occurrences of the object
        Returns:
        the number of occurrences of the object before this operation, zero if the object was not contained in the multiset

      • contains

        public boolean contains​(java.lang.Object object)
        Determines if the multiset contains the given element.
        Specified by:
        contains in interface java.util.Collection<E>
        Overrides:
        contains in class java.util.AbstractCollection<E>
        Parameters:
        object - the object to search for
        Returns:
        true if the multiset contains the given element

      • iterator

        public java.util.Iterator<E> iterator()
        Gets an iterator over the multiset elements. Elements present in the MultiSet more than once will be returned repeatedly.
        Specified by:
        iterator in interface java.util.Collection<E>
        Specified by:
        iterator in interface java.lang.Iterable<E>
        Specified by:
        iterator in interface MultiSet<E>
        Specified by:
        iterator in class java.util.AbstractCollection<E>
        Returns:
        the iterator

      • add

        public boolean add​(E object)
        Description copied from interface: MultiSet
        Adds one copy of the specified object to the MultiSet.

        If the object is already in the MultiSet.uniqueSet() then increment its count as reported by MultiSet.getCount(Object). Otherwise add it to the MultiSet.uniqueSet() and report its count as 1.

        Specified by:
        add in interface java.util.Collection<E>
        Specified by:
        add in interface MultiSet<E>
        Overrides:
        add in class java.util.AbstractCollection<E>
        Parameters:
        object - the object to add
        Returns:
        true always, as the size of the MultiSet is increased in any case

      • add

        public int add​(E object,
               int occurrences)
        Description copied from interface: MultiSet
        Adds a number of occurrences of the specified object to the MultiSet.

        If the object is already in the MultiSet.uniqueSet() then increment its count as reported by MultiSet.getCount(Object). Otherwise add it to the MultiSet.uniqueSet() and report its count as occurrences.

        Specified by:
        add in interface MultiSet<E>
        Parameters:
        object - the object to add
        occurrences - the number of occurrences to add, may be zero, in which case no change is made to the multiset
        Returns:
        the number of occurrences of the object in the multiset before this operation; possibly zero

      • clear

        public void clear()
        Clears the multiset removing all elements from the entrySet.
        Specified by:
        clear in interface java.util.Collection<E>
        Overrides:
        clear in class java.util.AbstractCollection<E>

      • remove

        public boolean remove​(java.lang.Object object)
        Description copied from interface: MultiSet
        Removes one occurrence of the given object from the MultiSet.

        If the number of occurrences after this operations is reduced to zero, the object will be removed from the MultiSet.uniqueSet().

        Specified by:
        remove in interface java.util.Collection<E>
        Specified by:
        remove in interface MultiSet<E>
        Overrides:
        remove in class java.util.AbstractCollection<E>
        Parameters:
        object - the object to remove
        Returns:
        true if this call changed the collection

      • remove

        public int remove​(java.lang.Object object,
                  int occurrences)
        Description copied from interface: MultiSet
        Removes a number of occurrences of the specified object from the MultiSet.

        If the number of occurrences to remove is greater than the actual number of occurrences in the multiset, the object will be removed from the multiset.

        Specified by:
        remove in interface MultiSet<E>
        Parameters:
        object - the object to remove
        occurrences - the number of occurrences to remove, may be zero, in which case no change is made to the multiset
        Returns:
        the number of occurrences of the object in the multiset before the operation; possibly zero

      • removeAll

        public boolean removeAll​(java.util.Collection<?> coll)
        Description copied from interface: MultiSet
        Remove all occurrences of all elements from this MultiSet represented in the given collection.
        Specified by:
        removeAll in interface java.util.Collection<E>
        Specified by:
        removeAll in interface MultiSet<E>
        Overrides:
        removeAll in class java.util.AbstractCollection<E>
        Parameters:
        coll - the collection of elements to remove
        Returns:
        true if this call changed the multiset

      • uniqueSet

        public java.util.Set<E> uniqueSet()
        Returns a view of the unique elements of this multiset.
        Specified by:
        uniqueSet in interface MultiSet<E>
        Returns:
        the set of unique elements in this multiset

      • entrySet

        public java.util.Set<MultiSet.Entry<E>> entrySet()
        Returns an unmodifiable view of the entries of this multiset.
        Specified by:
        entrySet in interface MultiSet<E>
        Returns:
        the set of entries in this multiset

      • equals

        public boolean equals​(java.lang.Object object)
        Description copied from interface: MultiSet
        Compares this MultiSet to another object.

        This MultiSet equals another object if it is also a MultiSet that contains the same number of occurrences of the same elements.

        Specified by:
        equals in interface java.util.Collection<E>
        Specified by:
        equals in interface MultiSet<E>
        Overrides:
        equals in class java.lang.Object
        Parameters:
        object - the object to compare to
        Returns:
        true if equal

      • hashCode

        public int hashCode()
        Description copied from interface: MultiSet
        Gets a hash code for the MultiSet compatible with the definition of equals. The hash code is defined as the sum total of a hash code for each element. The per element hash code is defined as (e==null ? 0 : e.hashCode()) ^ noOccurances).
        Specified by:
        hashCode in interface java.util.Collection<E>
        Specified by:
        hashCode in interface MultiSet<E>
        Overrides:
        hashCode in class java.lang.Object
        Returns:
        the hash code of the MultiSet

      • toString

        public java.lang.String toString()
        Implement a toString() method suitable for debugging.
        Overrides:
        toString in class java.util.AbstractCollection<E>
        Returns:
        a debugging toString