Package org.apache.commons.collections4.bag

Class 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:
    Serialized Form

    • Constructor Detail

      • 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 Detail

      • 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

      • 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

      • 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

      • 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

      • 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

      • 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