org.apache.commons.collections.collection
Class PredicatedCollection<E>

java.lang.Object
  extended by org.apache.commons.collections.collection.AbstractCollectionDecorator<E>
      extended by org.apache.commons.collections.collection.AbstractSerializableCollectionDecorator<E>
          extended by org.apache.commons.collections.collection.PredicatedCollection<E>
All Implemented Interfaces:
Serializable, Iterable<E>, Collection<E>
Direct Known Subclasses:
PredicatedBag, PredicatedBuffer, PredicatedList, PredicatedSet

public class PredicatedCollection<E>
extends AbstractSerializableCollectionDecorator<E>

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

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

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

Collection coll = PredicatedCollection.decorate(new ArrayList(), NotNullPredicate.INSTANCE);

This class is Serializable from Commons Collections 3.1.

Since:
Commons Collections 3.0
Version:
$Revision: 1.1.1.1 $ $Date: 2005/05/23 04:34:01 $
Author:
Stephen Colebourne, Matt Hall, John Watkinson, Paul Jack
See Also:
Serialized Form

Field Summary
protected  Predicate<? super E> predicate
          The predicate to use
 
Fields inherited from class org.apache.commons.collections.collection.AbstractCollectionDecorator
collection
 
Constructor Summary
protected PredicatedCollection(Collection<E> coll, Predicate<? super E> predicate)
          Constructor that wraps (not copies).
 
Method Summary
 boolean add(E object)
          Override to validate the object being added to ensure it matches the predicate.
 boolean addAll(Collection<? extends E> coll)
          Override to validate the objects being added to ensure they match the predicate.
static
<E> Collection
decorate(Collection<E> coll, Predicate<? super E> predicate)
          Factory method to create a predicated (validating) collection.
protected  void validate(E object)
          Validates the object being added to ensure it matches the predicate.
 
Methods inherited from class org.apache.commons.collections.collection.AbstractCollectionDecorator
clear, contains, containsAll, equals, getCollection, hashCode, isEmpty, iterator, remove, removeAll, retainAll, size, toArray, toArray, toString
 
Methods inherited from class java.lang.Object
clone, finalize, getClass, notify, notifyAll, wait, wait, wait
 

Field Detail

predicate

protected final Predicate<? super E> predicate
The predicate to use

Constructor Detail

PredicatedCollection

protected PredicatedCollection(Collection<E> coll,
                               Predicate<? super E> predicate)
Constructor that wraps (not copies).

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

Parameters:
coll - the collection to decorate, must not be null
predicate - the predicate to use for validation, must not be null
Throws:
IllegalArgumentException - if collection or predicate is null
IllegalArgumentException - if the collection contains invalid elements
Method Detail

decorate

public static <E> Collection decorate(Collection<E> coll,
                                      Predicate<? super E> predicate)
Factory method to create a predicated (validating) collection.

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

Parameters:
coll - the collection to decorate, must not be null
predicate - the predicate to use for validation, must not be null
Returns:
a new predicated collection
Throws:
IllegalArgumentException - if collection or predicate is null
IllegalArgumentException - if the collection contains invalid elements

validate

protected void validate(E object)
Validates the object being added to ensure it matches the predicate.

The predicate itself should not throw an exception, but return false to indicate that the object cannot be added.

Parameters:
object - the object being added
Throws:
IllegalArgumentException - if the add is invalid

add

public boolean add(E object)
Override to validate the object being added to ensure it matches the predicate.

Specified by:
add in interface Collection<E>
Overrides:
add in class AbstractCollectionDecorator<E>
Parameters:
object - the object being added
Returns:
the result of adding to the underlying collection
Throws:
IllegalArgumentException - if the add is invalid

addAll

public boolean addAll(Collection<? extends E> coll)
Override to validate the objects being added to ensure they match the predicate. If any one fails, no update is made to the underlying collection.

Specified by:
addAll in interface Collection<E>
Overrides:
addAll in class AbstractCollectionDecorator<E>
Parameters:
coll - the collection being added
Returns:
the result of adding to the underlying collection
Throws:
IllegalArgumentException - if the add is invalid


Copyright © 2005-2005 Apache Software Foundation, Matt Hall, John Watkinson. All Rights Reserved.