org.apache.commons.collections.Bag |
Known Indirect Subclasses |
Defines 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}
.
NOTE: This interface violates the Collection
contract.
The behavior specified in many of these methods is not the same
as the behavior specified by Collection
.
The noncompliant methods are clearly marked with "(Violation)".
Exercise caution when using a bag as a Collection
.
This violation resulted from the original specification of this interface. In an ideal world, the interface would be changed to fix the problems, however it has been decided to maintain backwards compatibility instead.
Public Methods | |||||||||||
---|---|---|---|---|---|---|---|---|---|---|---|
Adds
nCopies copies of the specified object to the Bag. | |||||||||||
(Violation)
Adds one copy the specified object to the Bag.
| |||||||||||
(Violation)
Returns
true if the bag contains all elements in
the given collection, respecting cardinality. | |||||||||||
Returns the number of occurrences (cardinality) of the given
object currently in the bag.
| |||||||||||
Returns an
Iterator over the entire set of members,
including copies due to cardinality. | |||||||||||
(Violation)
Removes all occurrences of the given object from the bag.
| |||||||||||
Removes
nCopies copies of the specified object from the Bag. | |||||||||||
(Violation)
Remove all elements represented in the given collection,
respecting cardinality.
| |||||||||||
(Violation)
Remove any members of the bag that are not in the given
collection, respecting cardinality.
| |||||||||||
Returns the total number of items in the bag across all types.
| |||||||||||
Returns a
Set of unique elements in the Bag. |
[Expand]
Inherited Methods | |||||||||||
---|---|---|---|---|---|---|---|---|---|---|---|
From interface
java.lang.Iterable
| |||||||||||
From interface
java.util.Collection
|
Adds nCopies
copies of the specified object to the Bag.
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 nCopies
.
object | the object to add |
---|---|
nCopies | the number of copies to add |
true
if the object was not already in the uniqueSet
(Violation) Adds one copy the specified object to the Bag.
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.
Since this method always increases the size of the bag,
according to the add(Object)
contract, it
should always return true
. Since it sometimes returns
false
, this method violates the contract.
object | the object to add |
---|
true
if the object was not already in the uniqueSet
(Violation)
Returns true
if the bag contains all elements in
the given collection, respecting cardinality. That is, if the
given collection coll
contains n
copies
of a given object, calling getCount(Object)
on that object must
be >= n
for all n
in coll
.
The containsAll(Collection)
method specifies
that cardinality should not be respected; this method should
return true if the bag contains at least one of every object contained
in the given collection.
coll | the collection to check against |
---|
true
if the Bag contains all the collection
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.
object | the object to search for |
---|
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.
(Violation) Removes all occurrences of the given object from the bag.
This will also remove the object from the uniqueSet()
.
According to the remove(Object)
method,
this method should only remove the first occurrence of the
given object, not all occurrences.
true
if this call changed the collection
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.
object | the object to remove |
---|---|
nCopies | the number of copies to remove |
true
if this call changed the collection
(Violation)
Remove all elements represented in the given collection,
respecting cardinality. That is, if the given collection
coll
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.
The removeAll(Collection)
method specifies
that cardinality should not be respected; this method should
remove all occurrences of every object contained in the
given collection.
coll | the collection to remove |
---|
true
if this call changed the collection
(Violation)
Remove any members of the bag that are not in the given
collection, respecting cardinality. That is, if the given
collection coll
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
!coll.contains(e)
, then remove e
and any
of its copies.
The retainAll(Collection)
method specifies
that cardinality should not be respected; this method should
keep all occurrences of every object contained in the
given collection.
coll | the collection to retain |
---|
true
if this call changed the collection
Returns the total number of items in the bag across all types.