public class

PredicatedBag

extends PredicatedCollection
implements Bag
java.lang.Object
   ↳ org.apache.commons.collections.collection.AbstractCollectionDecorator
     ↳ org.apache.commons.collections.collection.AbstractSerializableCollectionDecorator
       ↳ org.apache.commons.collections.collection.PredicatedCollection
         ↳ org.apache.commons.collections.bag.PredicatedBag
Known Direct Subclasses

Class Overview

Decorates another Bag to validate that additions match a specified predicate.

This bag exists to provide validation for the decorated bag. It is normally created to decorate an empty bag. If an object cannot be added to the bag, an IllegalArgumentException is thrown.

One usage would be to ensure that no null entries are added to the bag. 

Bag bag = PredicatedBag.decorate(new HashBag(), NotNullPredicate.INSTANCE);

This class is Serializable from Commons Collections 3.1.

Summary

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Inherited Fields
From class org.apache.commons.collections.collection.PredicatedCollection
From class org.apache.commons.collections.collection.AbstractCollectionDecorator
Protected Constructors
PredicatedBag(Bag bag, Predicate predicate)
Constructor that wraps (not copies).
Public Methods
boolean add(Object object, int count)
Adds nCopies copies of the specified object to the Bag.
static Bag decorate(Bag bag, Predicate predicate)
Factory method to create a predicated (validating) bag.
int getCount(Object object)
Returns the number of occurrences (cardinality) of the given object currently in the bag.
boolean remove(Object object, int count)
Removes nCopies copies of the specified object from the Bag.
Set uniqueSet()
Returns a Set of unique elements in the Bag.
Protected Methods
Bag getBag()
Gets the decorated bag.
[Expand]
Inherited Methods
From class org.apache.commons.collections.collection.PredicatedCollection
From class org.apache.commons.collections.collection.AbstractCollectionDecorator
From class java.lang.Object
From interface java.lang.Iterable
From interface java.util.Collection
From interface org.apache.commons.collections.Bag

Protected Constructors

protected PredicatedBag (Bag bag, Predicate predicate)

Constructor that wraps (not copies).

If there are any elements already in the bag being decorated, they are validated.

Parameters
bag the bag to decorate, must not be null
predicate the predicate to use for validation, must not be null
Throws
IllegalArgumentException if bag or predicate is null
IllegalArgumentException if the bag contains invalid elements

Public Methods

public boolean add (Object object, int count)

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.

Parameters
object the object to add
count the number of copies to add
Returns
  • true if the object was not already in the uniqueSet

public static Bag decorate (Bag bag, Predicate predicate)

Factory method to create a predicated (validating) bag.

If there are any elements already in the bag being decorated, they are validated.

Parameters
bag the bag to decorate, must not be null
predicate the predicate to use for validation, must not be null
Returns
  • a new predicated Bag
Throws
IllegalArgumentException if bag or predicate is null
IllegalArgumentException if the bag contains invalid elements

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.

Parameters
object the object to search for
Returns
  • the number of occurrences of the object, zero if not found

public boolean remove (Object object, int count)

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.

Parameters
object the object to remove
count the number of copies to remove
Returns
  • true if this call changed the collection

public Set uniqueSet ()

Returns a Set of unique elements in the Bag.

Uniqueness constraints are the same as those in Set.

Returns
  • the Set of unique Bag elements

Protected Methods

protected Bag getBag ()

Gets the decorated bag.

Returns
  • the decorated bag