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/*
 * Licensed to the Apache Software Foundation (ASF) under one or more
 * contributor license agreements.  See the NOTICE file distributed with
 * this work for additional information regarding copyright ownership.
 * The ASF licenses this file to You 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.collections4.collection;

import java.util.ArrayList;
import java.util.Collection;
import java.util.List;

import org.apache.commons.collections4.Transformer;

/**
 * Decorates another {@link Collection} to transform objects that are added.
 * 

* The add methods are affected by this class. * Thus objects must be removed or searched for using their transformed form. * For example, if the transformation converts Strings to Integers, you must * use the Integer form to remove objects. *

* This class is Serializable from Commons Collections 3.1. * * @param the type of the elements in the collection * @since 3.0 * @version $Id: TransformedCollection.java 1686855 2015-06-22 13:00:27Z tn $ */ public class TransformedCollection extends AbstractCollectionDecorator { /** Serialization version */ private static final long serialVersionUID = 8692300188161871514L; /** The transformer to use */ protected final Transformer transformer; /** * Factory method to create a transforming collection. *

* If there are any elements already in the collection being decorated, they * are NOT transformed. * Contrast this with {@link #transformedCollection(Collection, Transformer)}. * * @param the type of the elements in the collection * @param coll the collection to decorate, must not be null * @param transformer the transformer to use for conversion, must not be null * @return a new transformed collection * @throws NullPointerException if collection or transformer is null * @since 4.0 */ public static TransformedCollection transformingCollection(final Collection coll, final Transformer transformer) { return new TransformedCollection(coll, transformer); } /** * Factory method to create a transforming collection that will transform * existing contents of the specified collection. *

* If there are any elements already in the collection being decorated, they * will be transformed by this method. * Contrast this with {@link #transformingCollection(Collection, Transformer)}. * * @param the type of the elements in the collection * @param collection the collection to decorate, must not be null * @param transformer the transformer to use for conversion, must not be null * @return a new transformed Collection * @throws NullPointerException if collection or transformer is null * @since 4.0 */ public static TransformedCollection transformedCollection(final Collection collection, final Transformer transformer) { final TransformedCollection decorated = new TransformedCollection(collection, transformer); // null collection & transformer are disallowed by the constructor call above if (collection.size() > 0) { @SuppressWarnings("unchecked") // collection is of type E final E[] values = (E[]) collection.toArray(); // NOPMD - false positive for generics collection.clear(); for (final E value : values) { decorated.decorated().add(transformer.transform(value)); } } return decorated; } //----------------------------------------------------------------------- /** * Constructor that wraps (not copies). *

* If there are any elements already in the collection being decorated, they * are NOT transformed. * * @param coll the collection to decorate, must not be null * @param transformer the transformer to use for conversion, must not be null * @throws NullPointerException if collection or transformer is null */ protected TransformedCollection(final Collection coll, final Transformer transformer) { super(coll); if (transformer == null) { throw new NullPointerException("Transformer must not be null"); } this.transformer = transformer; } /** * Transforms an object. *

* The transformer itself may throw an exception if necessary. * * @param object the object to transform * @return a transformed object */ protected E transform(final E object) { return transformer.transform(object); } /** * Transforms a collection. *

* The transformer itself may throw an exception if necessary. * * @param coll the collection to transform * @return a transformed object */ protected Collection transform(final Collection coll) { final List list = new ArrayList(coll.size()); for (final E item : coll) { list.add(transform(item)); } return list; } //----------------------------------------------------------------------- @Override public boolean add(final E object) { return decorated().add(transform(object)); } @Override public boolean addAll(final Collection coll) { return decorated().addAll(transform(coll)); } }





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