org.apache.commons.collections
Interface Bag

All Superinterfaces:
Collection
All Known Subinterfaces:
SortedBag
All Known Implementing Classes:
DefaultMapBag, HashBag, AbstractBag, TreeBag

public interface Bag
extends Collection

A Collection that counts the number of times an object appears in the collection. Suppose you have a Bag that contains {a, a, b, c}. Calling getCount(Object) on a would return 2, while calling uniqueSet() would return {a, b, c}.

Author:
Chuck Burdick

Method Summary
 boolean add(Object o)
          Add the given object to the bag and keep a count.
 boolean add(Object o, int i)
          Add i copies of the given object to the bag and keep a count.
 boolean containsAll(Collection c)
          Returns true if the bag contains all elements in the given collection, respecting cardinality.
 int getCount(Object o)
          Return the number of occurrences (cardinality) of the given object currently in the bag.
 Iterator iterator()
          Returns an Iterator over the entire set of members, including copies due to cardinality.
 boolean remove(Object o)
          Remove all occurrences of the given object from the bag, and do not represent the object in the uniqueSet().
 boolean remove(Object o, int i)
          Remove the given number of occurrences from the bag.
 boolean removeAll(Collection c)
          Remove all elements represented in the given collection, respecting cardinality.
 boolean retainAll(Collection c)
          Remove any members of the bag that are not in the given collection, respecting cardinality.
 int size()
          Returns the total number of items in the bag across all types.
 Set uniqueSet()
          The Set of unique members that represent all members in the bag.
 
Methods inherited from interface java.util.Collection
addAll, clear, contains, equals, hashCode, isEmpty, toArray, toArray
 

Method Detail

add

public boolean add(Object o)
Add the given object to the bag and keep a count. If the object is already in the uniqueSet() then increment its count as reported by getCount(Object). Otherwise add it to the uniqueSet() and report its count as 1.
Specified by:
add in interface Collection
Returns:
true if the object was not already in the uniqueSet
See Also:
getCount(Object)

add

public boolean add(Object o,
                   int i)
Add i copies of the given object to the bag and keep a count.
Returns:
true if the object was not already in the uniqueSet
See Also:
add(Object), getCount(Object)

containsAll

public boolean containsAll(Collection c)
Returns true if the bag contains all elements in the given collection, respecting cardinality. That is, if the given collection C contains n copies of a given object, calling getCount(Object) on that object must be >= n for all n in C.
Specified by:
containsAll in interface Collection

getCount

public int getCount(Object o)
Return the number of occurrences (cardinality) of the given object currently in the bag. If the object does not exist in the bag, return 0.

iterator

public Iterator iterator()
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 Collection

remove

public boolean remove(Object o)
Remove all occurrences of the given object from the bag, and do not represent the object in the uniqueSet().
Specified by:
remove in interface Collection
Returns:
true if this call changed the collection
See Also:
remove(Object, int)

remove

public boolean remove(Object o,
                      int i)
Remove the given number of occurrences from the bag. If the bag contains i occurrences or less, the item will be removed from the uniqueSet().
Returns:
true if this call changed the collection
See Also:
getCount(Object), remove(Object)

removeAll

public boolean removeAll(Collection c)
Remove all elements represented in the given collection, respecting cardinality. That is, if the given collection C 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.
Specified by:
removeAll in interface Collection
Returns:
true if this call changed the collection

retainAll

public boolean retainAll(Collection c)
Remove any members of the bag that are not in the given collection, respecting cardinality. That is, if the given collection C contains n copies of a given object and the bag has m > n copies, then delete m - n copies from the bag. In addition, if e is an object in the bag but !C.contains(e), then remove e and any of its copies.
Specified by:
retainAll in interface Collection
Returns:
true if this call changed the collection

size

public int size()
Returns the total number of items in the bag across all types.
Specified by:
size in interface Collection

uniqueSet

public Set uniqueSet()
The Set of unique members that represent all members in the bag. Uniqueness constraints are the same as those in Set.


Copyright © 2001 Apache Software Foundation. Documenation generated April 2 2002.