org.apache.commons.collections.bag

Class TransformedBag

Implemented Interfaces:
Bag, Collection, Serializable
Known Direct Subclasses:
TransformedSortedBag

public class TransformedBag
extends TransformedCollection
implements Bag

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.

Version:
$Revision: 1.7 $ $Date: 2004/06/03 22:02:12 $
Author:
Stephen Colebourne
Since:
Commons Collections 3.0

Field Summary

Fields inherited from class org.apache.commons.collections.collection.TransformedCollection

transformer

Fields inherited from class org.apache.commons.collections.collection.AbstractCollectionDecorator

collection

Constructor Summary

TransformedBag(Bag bag, Transformer transformer)
Constructor that wraps (not copies).

Method Summary

boolean
add(Object object, int nCopies)
Adds nCopies copies of the specified object to the Bag.
static Bag
decorate(Bag bag, Transformer transformer)
Factory method to create a transforming bag.
protected Bag
getBag()
Gets the decorated bag.
int
getCount(Object object)
Returns the number of occurrences (cardinality) of the given object currently in the bag.
boolean
remove(Object object, int nCopies)
Removes nCopies copies of the specified object from the Bag.
Set
uniqueSet()
Returns a Set of unique elements in the Bag.

Methods inherited from class org.apache.commons.collections.collection.TransformedCollection

add, addAll, decorate, transform, transform

Methods inherited from class org.apache.commons.collections.collection.AbstractCollectionDecorator

add, addAll, clear, contains, containsAll, equals, getCollection, hashCode, isEmpty, iterator, remove, removeAll, retainAll, size, toArray, toArray, toString

Constructor Details

TransformedBag

protected TransformedBag(Bag bag,
                         Transformer 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

Method Details

add

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

decorate

public static Bag decorate(Bag bag,
                           Transformer transformer)
Factory method to create a transforming bag.

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
Returns:
a new transformed Bag

getBag

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

getCount

public int getCount(Object object)
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
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)
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
Parameters:
object - the object to remove
nCopies - the number of copies to remove
Returns:
true if this call changed the collection

uniqueSet

public Set uniqueSet()
Returns a Set of unique elements in the Bag.

Uniqueness constraints are the same as those in java.util.Set.

Specified by:
uniqueSet in interface Bag
Returns:
the Set of unique Bag elements

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