| /* |
| * Copyright 2003-2004 The Apache Software Foundation |
| * |
| * Licensed under the Apache License, Version 2.0 (the "License"); |
| * you may not use this file except in compliance with the License. |
| * You may obtain a copy of the License at |
| * |
| * http://www.apache.org/licenses/LICENSE-2.0 |
| * |
| * Unless required by applicable law or agreed to in writing, software |
| * distributed under the License is distributed on an "AS IS" BASIS, |
| * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. |
| * See the License for the specific language governing permissions and |
| * limitations under the License. |
| */ |
| package org.apache.commons.collections.collection; |
| |
| import java.util.Collection; |
| import java.util.Iterator; |
| |
| import org.apache.commons.collections.Predicate; |
| |
| /** |
| * Decorates another <code>Collection</code> to validate that additions |
| * match a specified predicate. |
| * <p> |
| * 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. |
| * <p> |
| * One usage would be to ensure that no null entries are added to the collection. |
| * <pre>Collection coll = PredicatedCollection.decorate(new ArrayList(), NotNullPredicate.INSTANCE);</pre> |
| * <p> |
| * This class is Serializable from Commons Collections 3.1. |
| * |
| * @since Commons Collections 3.0 |
| * @version $Revision: 1.1 $ $Date: 2009/05/27 22:16:27 $ |
| * |
| * @author Stephen Colebourne |
| * @author Paul Jack |
| */ |
| public class PredicatedCollection extends AbstractSerializableCollectionDecorator { |
| |
| /** Serialization version */ |
| private static final long serialVersionUID = -5259182142076705162L; |
| |
| /** The predicate to use */ |
| protected final Predicate predicate; |
| |
| /** |
| * Factory method to create a predicated (validating) collection. |
| * <p> |
| * 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 |
| * @return a new predicated collection |
| * @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). |
| * <p> |
| * 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. |
| * <p> |
| * 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); |
| } |
| |
| } |