Package org.apache.commons.collections4.multiset

Class AbstractMultiSet<E>

java.lang.Object
java.util.AbstractCollection<E>
org.apache.commons.collections4.multiset.AbstractMultiSet<E>
Type Parameters:
E - the type held in the multiset
All Implemented Interfaces:
Iterable<E>, Collection<E>, MultiSet<E>
Direct Known Subclasses:
AbstractMapMultiSet
public abstract class AbstractMultiSet<E> extends AbstractCollection<E> implements MultiSet<E>
Abstract implementation of the MultiSet interface to simplify the creation of subclass implementations.
Since:
4.1

  • Constructor Details

    • AbstractMultiSet

      protected AbstractMultiSet()
      Constructor needed for subclass serialisation.

  • Method Details

    • 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 Collection<E>
      Specified by:
      add in interface MultiSet<E>
      Overrides:
      add in class 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 Collection<E>
      Overrides:
      clear in class AbstractCollection<E>

    • contains

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

    • createEntrySet

      protected Set<MultiSet.Entry<E>> createEntrySet()
      Create a new view for the set of entries in this multiset.
      Returns:
      a view of the set of entries

    • createEntrySetIterator

      protected abstract Iterator<MultiSet.Entry<E>> createEntrySetIterator()
      Creates an entry set iterator. Subclasses can override this to return iterators with different properties.
      Returns:
      the entrySet iterator

    • createUniqueSet

      protected Set<E> createUniqueSet()
      Create a new view for the set of unique elements in this multiset.
      Returns:
      a view of the set of unique elements

    • createUniqueSetIterator

      protected Iterator<E> createUniqueSetIterator()
      Creates a unique set iterator. Subclasses can override this to return iterators with different properties.
      Returns:
      the uniqueSet iterator

    • doReadObject

      protected void doReadObject(ObjectInputStream in) throws IOException, ClassNotFoundException
      Read the multiset in using a custom routine.
      Parameters:
      in - the input stream
      Throws:
      IOException - any of the usual I/O related exceptions
      ClassNotFoundException - if the stream contains an object which class can not be loaded
      ClassCastException - if the stream does not contain the correct objects

    • doWriteObject

      protected void doWriteObject(ObjectOutputStream out) throws IOException
      Write the multiset out using a custom routine.
      Parameters:
      out - the output stream
      Throws:
      IOException - any of the usual I/O related exceptions

    • entrySet

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

    • getCount

      public int getCount(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

    • 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()) ^ noOccurrences).
      Specified by:
      hashCode in interface Collection<E>
      Specified by:
      hashCode in interface MultiSet<E>
      Overrides:
      hashCode in class Object
      Returns:
      the hash code of the MultiSet

    • iterator

      public 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 Collection<E>
      Specified by:
      iterator in interface Iterable<E>
      Specified by:
      iterator in interface MultiSet<E>
      Specified by:
      iterator in class AbstractCollection<E>
      Returns:
      the iterator

    • remove

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

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

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

    • remove

      public int remove(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(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 Collection<E>
      Specified by:
      removeAll in interface MultiSet<E>
      Overrides:
      removeAll in class AbstractCollection<E>
      Parameters:
      coll - the collection of elements to remove
      Returns:
      true if this call changed the multiset

    • 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

    • size

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

    • toString

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

    • uniqueElements

      protected abstract int uniqueElements()
      Returns the number of unique elements in this multiset.
      Returns:
      the number of unique elements

    • uniqueSet

      public 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