Package org.apache.commons.collections4.bag

Class PredicatedBag<E>

java.lang.Object
org.apache.commons.collections4.collection.AbstractCollectionDecorator<E>
org.apache.commons.collections4.collection.PredicatedCollection<E>
org.apache.commons.collections4.bag.PredicatedBag<E>
Type Parameters:
E - the type of elements in this bag
All Implemented Interfaces:
Serializable, Iterable<E>, Collection<E>, Bag<E>
Direct Known Subclasses:
PredicatedSortedBag
public class PredicatedBag<E> extends PredicatedCollection<E> implements Bag<E>
Decorates another Bag to validate that additions match a specified predicate.

This bag exists to provide validation for the decorated bag. It is normally created to decorate an empty bag. If an object cannot be added to the bag, an IllegalArgumentException is thrown.

One usage would be to ensure that no null entries are added to the bag. 

 Bag bag = PredicatedBag.predicatedBag(new HashBag(), NotNullPredicate.INSTANCE);

This class is Serializable from Commons Collections 3.1.

Since:
3.0
See Also:

  • Constructor Details

    • PredicatedBag

      protected PredicatedBag(Bag<E> bag, Predicate<? super E> predicate)
      Constructor that wraps (not copies).

      If there are any elements already in the bag being decorated, they are validated.

      Parameters:
      bag - the bag to decorate, must not be null
      predicate - the predicate to use for validation, must not be null
      Throws:
      NullPointerException - if bag or predicate is null
      IllegalArgumentException - if the bag contains invalid elements

  • Method Details

    • predicatedBag

      public static <E> PredicatedBag<E> predicatedBag(Bag<E> bag, Predicate<? super E> predicate)
      Factory method to create a predicated (validating) bag.

      If there are any elements already in the bag being decorated, they are validated.

      Type Parameters:
      E - the type of the elements in the bag
      Parameters:
      bag - the bag to decorate, must not be null
      predicate - the predicate to use for validation, must not be null
      Returns:
      a new predicated Bag
      Throws:
      NullPointerException - if bag or predicate is null
      IllegalArgumentException - if the bag contains invalid elements
      Since:
      4.0

    • 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>
      Parameters:
      object - the object to add
      count - the number of copies to add
      Returns:
      true if the object was not already in the uniqueSet

    • decorated

      protected Bag<E> decorated()
      Gets the decorated bag.
      Overrides:
      decorated in class AbstractCollectionDecorator<E>
      Returns:
      the decorated bag

    • equals

      public boolean equals(Object object)
      Specified by:
      equals in interface Collection<E>
      Overrides:
      equals in class Object

    • getCount

      public int getCount(Object object)
      Description copied from interface: Bag
      Returns the number of occurrences (cardinality) of the given object currently in the bag. If the object does not exist in the bag, return 0.
      Specified by:
      getCount in interface Bag<E>
      Parameters:
      object - the object to search for
      Returns:
      the number of occurrences of the object, zero if not found

    • hashCode

      public int hashCode()
      Specified by:
      hashCode in interface Collection<E>
      Overrides:
      hashCode in class Object

    • 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>
      Parameters:
      object - the object to remove
      count - the number of copies to remove
      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>
      Returns:
      the Set of unique Bag elements