Package org.apache.commons.collections4.bag

Class UnmodifiableBag<E>

java.lang.Object
org.apache.commons.collections4.collection.AbstractCollectionDecorator<E>
org.apache.commons.collections4.bag.AbstractBagDecorator<E>
org.apache.commons.collections4.bag.UnmodifiableBag<E>
Type Parameters:
E - the type of elements in this bag
All Implemented Interfaces:
Serializable, Iterable<E>, Collection<E>, Bag<E>, Unmodifiable
public final class UnmodifiableBag<E> extends AbstractBagDecorator<E> implements Unmodifiable
Decorates another Bag to ensure it can't be altered.

This class is Serializable from Commons Collections 3.1.

Attempts to modify it will result in an UnsupportedOperationException.

Since:
3.0
See Also:

  • Method Details

    • unmodifiableBag

      public static <E> Bag<E> unmodifiableBag(Bag<? extends E> bag)
      Factory method to create an unmodifiable bag.

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

      Type Parameters:
      E - the type of the elements in the bag
      Parameters:
      bag - the bag to decorate, must not be null
      Returns:
      an unmodifiable Bag
      Throws:
      NullPointerException - if bag is null
      Since:
      4.0

    • add

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

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

      Since this method always increases the size of the bag, according to the Collection.add(Object) contract, it should always return true. Since it sometimes returns false, this method violates the contract.

      Specified by:
      add in interface Bag<E>
      Specified by:
      add in interface Collection<E>
      Overrides:
      add in class AbstractCollectionDecorator<E>
      Parameters:
      object - the object to add
      Returns:
      true if the object was not already in the uniqueSet

    • add

      public boolean add(E object, int count)
      Description copied from interface: Bag
      Adds nCopies copies of the specified object to the Bag.

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

      Specified by:
      add in interface Bag<E>
      Overrides:
      add in class AbstractBagDecorator<E>
      Parameters:
      object - the object to add
      count - the number of copies to add
      Returns:
      true if the object was not already in the uniqueSet

    • 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>

    • iterator

      public Iterator<E> iterator()
      Description copied from interface: Bag
      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 Bag<E>
      Specified by:
      iterator in interface Collection<E>
      Specified by:
      iterator in interface Iterable<E>
      Overrides:
      iterator in class AbstractCollectionDecorator<E>
      Returns:
      iterator over all elements in the Bag

    • remove

      public boolean remove(Object object)
      Description copied from interface: Bag
      (Violation) Removes all occurrences of the given object from the bag.

      This will also remove the object from the Bag.uniqueSet().

      According to the Collection.remove(Object) method, this method should only remove the first occurrence of the given object, not all occurrences.

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

    • remove

      public boolean remove(Object object, int count)
      Description copied from interface: Bag
      Removes nCopies copies of the specified object from the Bag.

      If the number of copies to remove is greater than the actual number of copies in the Bag, no error is thrown.

      Specified by:
      remove in interface Bag<E>
      Overrides:
      remove in class AbstractBagDecorator<E>
      Parameters:
      object - the object to remove
      count - the number of copies to remove
      Returns:
      true if this call changed the collection

    • removeAll

      public boolean removeAll(Collection<?> coll)
      Description copied from interface: Bag
      (Violation) Remove all elements represented in the given collection, respecting cardinality. That is, if the given collection coll contains n copies of a given object, the bag will have n fewer copies, assuming the bag had at least n copies to begin with.

      The Collection.removeAll(Collection) method specifies that cardinality should not be respected; this method should remove all occurrences of every object contained in the given collection.

      Specified by:
      removeAll in interface Bag<E>
      Specified by:
      removeAll in interface Collection<E>
      Overrides:
      removeAll in class AbstractCollectionDecorator<E>
      Parameters:
      coll - the collection 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

    • retainAll

      public boolean retainAll(Collection<?> coll)
      Description copied from interface: Bag
      (Violation) Remove any members of the bag that are not in the given collection, respecting cardinality. That is, if the given collection coll contains n copies of a given object and the bag has m &gt; n copies, then delete m - n copies from the bag. In addition, if e is an object in the bag but !coll.contains(e), then remove e and any of its copies.

      The Collection.retainAll(Collection) method specifies that cardinality should not be respected; this method should keep all occurrences of every object contained in the given collection.

      Specified by:
      retainAll in interface Bag<E>
      Specified by:
      retainAll in interface Collection<E>
      Overrides:
      retainAll in class AbstractCollectionDecorator<E>
      Parameters:
      coll - the collection to retain
      Returns:
      true if this call changed the collection

    • uniqueSet

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

      Uniqueness constraints are the same as those in Set.

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