Package org.apache.commons.collections4.bag

Class TransformedBag<E>

java.lang.Object
org.apache.commons.collections4.collection.AbstractCollectionDecorator<E>
org.apache.commons.collections4.collection.TransformedCollection<E>
org.apache.commons.collections4.bag.TransformedBag<E>
Type Parameters:
E - the type of elements in this bag
All Implemented Interfaces:
Serializable, Iterable<E>, Collection<E>, Bag<E>
Direct Known Subclasses:
TransformedSortedBag
public class TransformedBag<E> extends TransformedCollection<E> implements Bag<E>
Decorates another Bag to transform objects that are added.

The add methods are affected by this class. Thus objects must be removed or searched for using their transformed form. For example, if the transformation converts Strings to Integers, you must use the Integer form to remove objects.

This class is Serializable from Commons Collections 3.1.

Since:
3.0
See Also:

  • Constructor Details

    • TransformedBag

      protected TransformedBag(Bag<E> bag, Transformer<? super E,? extends E> transformer)
      Constructor that wraps (not copies).

      If there are any elements already in the bag being decorated, they are NOT transformed.

      Parameters:
      bag - the bag to decorate, must not be null
      transformer - the transformer to use for conversion, must not be null
      Throws:
      NullPointerException - if bag or transformer is null

  • Method Details

    • transformedBag

      public static <E> Bag<E> transformedBag(Bag<E> bag, Transformer<? super E,? extends E> transformer)
      Factory method to create a transforming bag that will transform existing contents of the specified bag.

      If there are any elements already in the bag being decorated, they will be transformed by this method. Contrast this with transformingBag(Bag, Transformer).

      Type Parameters:
      E - the type of the elements in the bag
      Parameters:
      bag - the bag to decorate, must not be null
      transformer - the transformer to use for conversion, must not be null
      Returns:
      a new transformed Bag
      Throws:
      NullPointerException - if bag or transformer is null
      Since:
      4.0

    • transformingBag

      public static <E> Bag<E> transformingBag(Bag<E> bag, Transformer<? super E,? extends E> transformer)
      Factory method to create a transforming bag.

      If there are any elements already in the bag being decorated, they are NOT transformed. Contrast this with transformedBag(Bag, Transformer).

      Type Parameters:
      E - the type of the elements in the bag
      Parameters:
      bag - the bag to decorate, must not be null
      transformer - the transformer to use for conversion, must not be null
      Returns:
      a new transformed Bag
      Throws:
      NullPointerException - if bag or transformer is null
      Since:
      4.0

    • add

      public boolean add(E object, int nCopies)
      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
      nCopies - the number of copies to add
      Returns:
      true if the object was not already in the uniqueSet

    • equals

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

    • getBag

      protected Bag<E> getBag()
      Gets the decorated bag.
      Returns:
      the decorated bag

    • 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 nCopies)
      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
      nCopies - 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