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*
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* Collection to validate that additions
* match a specified predicate.
*
* If an object cannot be added to the collection, an IllegalArgumentException
* is thrown.
*
* @since Commons Collections 3.0
* @version $Revision: 1.2 $ $Date: 2004/01/14 21:43:18 $
*
* @author Stephen Colebourne
* @author Paul Jack
*/
public class PredicatedCollection extends AbstractCollectionDecorator {
/** The predicate to use */
protected final Predicate predicate;
/**
* Factory method to create a predicated (validating) collection.
*
* If there are any elements already in the collection being decorated, they
* are validated.
*
* @param coll the collection to decorate, must not be null
* @param predicate the predicate to use for validation, must not be null
* @throws IllegalArgumentException if collection or predicate is null
* @throws IllegalArgumentException if the collection contains invalid elements
*/
public static Collection decorate(Collection coll, Predicate predicate) {
return new PredicatedCollection(coll, predicate);
}
//-----------------------------------------------------------------------
/**
* Constructor that wraps (not copies).
*
* If there are any elements already in the collection being decorated, they
* are validated.
*
* @param coll the collection to decorate, must not be null
* @param predicate the predicate to use for validation, must not be null
* @throws IllegalArgumentException if collection or predicate is null
* @throws IllegalArgumentException if the collection contains invalid elements
*/
protected PredicatedCollection(Collection coll, Predicate predicate) {
super(coll);
if (predicate == null) {
throw new IllegalArgumentException("Predicate must not be null");
}
this.predicate = predicate;
for (Iterator it = coll.iterator(); it.hasNext(); ) {
validate(it.next());
}
}
/**
* 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.
*
* @param object the object being added
* @throws IllegalArgumentException if the add is invalid
*/
protected void validate(Object object) {
if (predicate.evaluate(object) == false) {
throw new IllegalArgumentException("Cannot add Object '" + object + "' - Predicate rejected it");
}
}
//-----------------------------------------------------------------------
/**
* Override to validate the object being added to ensure it matches
* the predicate.
*
* @param object the object being added
* @return the result of adding to the underlying collection
* @throws IllegalArgumentException if the add is invalid
*/
public boolean add(Object object) {
validate(object);
return getCollection().add(object);
}
/**
* 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.
*
* @param coll the collection being added
* @return the result of adding to the underlying collection
* @throws IllegalArgumentException if the add is invalid
*/
public boolean addAll(Collection coll) {
for (Iterator it = coll.iterator(); it.hasNext(); ) {
validate(it.next());
}
return getCollection().addAll(coll);
}
}