org.apache.commons.collections.collection
Class PredicatedCollection

java.lang.Object
  |
  +--org.apache.commons.collections.collection.AbstractCollectionDecorator
        |
        +--org.apache.commons.collections.collection.AbstractSerializableCollectionDecorator
              |
              +--org.apache.commons.collections.collection.PredicatedCollection

All Implemented Interfaces:

Collection, Serializable

Direct Known Subclasses:

PredicatedBag, PredicatedBuffer, PredicatedList, PredicatedSet

public class PredicatedCollection

extends AbstractSerializableCollectionDecorator

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: 1.7 $ $Date: 2004/06/03 22:02:13 $

Author:

Stephen Colebourne, Paul Jack

See Also:

Serialized Form

Field Summary

protected Predicate

predicate The predicate to use

Fields inherited from class org.apache.commons.collections.collection.AbstractCollectionDecorator

collection

Constructor Summary

protected

PredicatedCollection(Collection coll, Predicate predicate) Constructor that wraps (not copies).

Method Summary

boolean	add(Object object) Override to validate the object being added to ensure it matches the predicate.
boolean	addAll(Collection coll) Override to validate the objects being added to ensure they match the predicate.
static Collection	decorate(Collection coll, Predicate predicate) Factory method to create a predicated (validating) collection.
protected void	validate(Object 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 predicate

The predicate to use

Constructor Detail

PredicatedCollection

protected PredicatedCollection(Collection coll,
                               Predicate 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 Collection decorate(Collection coll,
                                  Predicate 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(Object 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(Object object)

Override to validate the object being added to ensure it matches the predicate.

Specified by:

add in interface Collection

Overrides:

add in class AbstractCollectionDecorator

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 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

Overrides:

addAll in class AbstractCollectionDecorator

Parameters:

coll - the collection being added

Returns:

the result of adding to the underlying collection

Throws:

IllegalArgumentException - if the add is invalid