Package org.apache.commons.collections4.multiset

Class UnmodifiableMultiSet<E>

java.lang.Object
org.apache.commons.collections4.collection.AbstractCollectionDecorator<E>
org.apache.commons.collections4.multiset.AbstractMultiSetDecorator<E>
org.apache.commons.collections4.multiset.UnmodifiableMultiSet<E>
Type Parameters:
E - the type held in the multiset
All Implemented Interfaces:
Serializable, Iterable<E>, Collection<E>, MultiSet<E>, Unmodifiable
public final class UnmodifiableMultiSet<E> extends AbstractMultiSetDecorator<E> implements Unmodifiable
Decorates another MultiSet to ensure it can't be altered.

Attempts to modify it will result in an UnsupportedOperationException.

Since:
4.1
See Also:

  • Field Details

    • serialVersionUID

      private static final long serialVersionUID
      Serialization version
      See Also:

  • Constructor Details

    • UnmodifiableMultiSet

      private UnmodifiableMultiSet(MultiSet<? extends E> multiset)
      Constructor that wraps (not copies).
      Parameters:
      multiset - the multiset to decorate, may not be null
      Throws:
      NullPointerException - if multiset is null

  • Method Details

    • unmodifiableMultiSet

      public static <E> MultiSet<E> unmodifiableMultiSet(MultiSet<? extends E> multiset)
      Factory method to create an unmodifiable multiset.

      If the multiset passed in is already unmodifiable, it is returned.

      Type Parameters:
      E - the type of the elements in the multiset
      Parameters:
      multiset - the multiset to decorate, may not be null
      Returns:
      an unmodifiable MultiSet
      Throws:
      NullPointerException - if multiset is null

    • writeObject

      private void writeObject(ObjectOutputStream out) throws IOException
      Write the collection out using a custom routine.
      Parameters:
      out - the output stream
      Throws:
      IOException - if an error occurs while writing to the stream

    • readObject

      private void readObject(ObjectInputStream in) throws IOException, ClassNotFoundException
      Read the collection in using a custom routine.
      Parameters:
      in - the input stream
      Throws:
      IOException - if an error occurs while reading from the stream
      ClassNotFoundException - if an object read from the stream can not be loaded
      ClassCastException - if deserialised object has wrong type

    • iterator

      public Iterator<E> iterator()
      Description copied from interface: MultiSet
      Returns an Iterator over the entire set of members, including copies due to cardinality. This iterator is fail-fast and will not tolerate concurrent modifications.
      Specified by:
      iterator in interface Collection<E>
      Specified by:
      iterator in interface Iterable<E>
      Specified by:
      iterator in interface MultiSet<E>
      Overrides:
      iterator in class AbstractCollectionDecorator<E>
      Returns:
      iterator over all elements in the MultiSet

    • 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 AbstractCollectionDecorator<E>
      Parameters:
      object - the object to add
      Returns:
      true always, as the size of the MultiSet is increased in any case

    • addAll

      public boolean addAll(Collection<? extends E> coll)
      Specified by:
      addAll in interface Collection<E>
      Overrides:
      addAll in class AbstractCollectionDecorator<E>

    • clear

      public void clear()
      Specified by:
      clear in interface Collection<E>
      Overrides:
      clear in class AbstractCollectionDecorator<E>

    • 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 operations 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 AbstractCollectionDecorator<E>
      Parameters:
      object - the object to remove
      Returns:
      true if this call changed the collection

    • removeIf

      public boolean removeIf(Predicate<? super E> filter)
      Specified by:
      removeIf in interface Collection<E>
      Overrides:
      removeIf in class AbstractCollectionDecorator<E>
      Since:
      4.4

    • 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 AbstractCollectionDecorator<E>
      Parameters:
      coll - the collection of elements to remove
      Returns:
      true if this call changed the multiset

    • retainAll

      public boolean retainAll(Collection<?> coll)
      Description copied from interface: MultiSet
      Remove any elements of this MultiSet that are not contained in the given collection.
      Specified by:
      retainAll in interface Collection<E>
      Specified by:
      retainAll in interface MultiSet<E>
      Overrides:
      retainAll in class AbstractCollectionDecorator<E>
      Parameters:
      coll - the collection of elements to retain
      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>
      Overrides:
      setCount in class AbstractMultiSetDecorator<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

    • add

      public int add(E object, int count)
      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>
      Overrides:
      add in class AbstractMultiSetDecorator<E>
      Parameters:
      object - the object to add
      count - 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

    • remove

      public int remove(Object object, int count)
      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>
      Overrides:
      remove in class AbstractMultiSetDecorator<E>
      Parameters:
      object - the object to remove
      count - 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

    • uniqueSet

      public Set<E> uniqueSet()
      Description copied from interface: MultiSet
      Returns a Set of unique elements in the MultiSet.

      Uniqueness constraints are the same as those in Set.

      The returned set is backed by this multiset, so any change to either is immediately reflected in the other. Only removal operations are supported, in which case all occurrences of the element are removed from the backing multiset.

      Specified by:
      uniqueSet in interface MultiSet<E>
      Overrides:
      uniqueSet in class AbstractMultiSetDecorator<E>
      Returns:
      the Set of unique MultiSet elements

    • entrySet

      public Set<MultiSet.Entry<E>> entrySet()
      Description copied from interface: MultiSet
      Returns a Set of all entries contained in the MultiSet.

      The returned set is backed by this multiset, so any change to either is immediately reflected in the other.

      Specified by:
      entrySet in interface MultiSet<E>
      Overrides:
      entrySet in class AbstractMultiSetDecorator<E>
      Returns:
      the Set of MultiSet entries