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

java.lang.Object
  org.apache.commons.collections.collection.AbstractCollectionDecorator<E>
      org.apache.commons.collections.collection.AbstractSerializableCollectionDecorator<E>
          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