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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.bag;

import java.io.IOException;
import java.io.ObjectInputStream;
import java.io.ObjectOutputStream;
import java.util.Collection;
import java.util.Iterator;

import org.apache.commons.collections4.Bag;

/**
 * Decorates another {@link Bag} to comply with the Collection contract.
 * 

* By decorating an existing {@link Bag} instance with a {@link CollectionBag}, * it can be safely passed on to methods that require Collection types that * are fully compliant with the Collection contract. *

* The method javadoc highlights the differences compared to the original Bag interface. * * @see Bag * @param the type of elements in this bag * @since 4.0 */ public final class CollectionBag extends AbstractBagDecorator { /** Serialization version */ private static final long serialVersionUID = -2560033712679053143L; /** * Factory method to create a bag that complies to the Collection contract. * * @param the type of the elements in the bag * @param bag the bag to decorate, must not be null * @return a Bag that complies to the Collection contract * @throws NullPointerException if bag is null */ public static Bag collectionBag(final Bag bag) { return new CollectionBag<>(bag); } //----------------------------------------------------------------------- /** * Constructor that wraps (not copies). * * @param bag the bag to decorate, must not be null * @throws NullPointerException if bag is null */ public CollectionBag(final Bag bag) { super(bag); } //----------------------------------------------------------------------- /** * Write the collection out using a custom routine. * * @param out the output stream * @throws IOException if an error occurs while writing to the stream */ private void writeObject(final ObjectOutputStream out) throws IOException { out.defaultWriteObject(); out.writeObject(decorated()); } /** * Read the collection in using a custom routine. * * @param in the input stream * @throws IOException if an error occurs while reading from the stream * @throws ClassNotFoundException if an object read from the stream can not be loaded * @throws ClassCastException if deserialised object has wrong type */ @SuppressWarnings("unchecked") // will throw CCE, see Javadoc private void readObject(final ObjectInputStream in) throws IOException, ClassNotFoundException { in.defaultReadObject(); setCollection((Collection) in.readObject()); } //----------------------------------------------------------------------- // Collection interface //----------------------------------------------------------------------- /** * (Change) * Returns true if the bag contains all elements in * the given collection, not respecting cardinality. That is, * if the given collection coll contains at least one of * every object contained in this object. * * @param coll the collection to check against * @return true if the Bag contains at least one of every object in the collection */ @Override public boolean containsAll(final Collection coll) { final Iterator e = coll.iterator(); while (e.hasNext()) { if(!contains(e.next())) { return false; } } return true; } /** * (Change) * Adds one copy of the specified object to the Bag. *

* Since this method always increases the size of the bag, it * will always return true. * * @param object the object to add * @return true, always */ @Override public boolean add(final E object) { return add(object, 1); } @Override public boolean addAll(final Collection coll) { boolean changed = false; final Iterator i = coll.iterator(); while (i.hasNext()) { final boolean added = add(i.next(), 1); changed = changed || added; } return changed; } /** * (Change) * Removes the first occurrence of the given object from the bag. *

* This will also remove the object from the {@link #uniqueSet()} if the * bag contains no occurrence anymore of the object after this operation. * * @param object the object to remove * @return true if this call changed the collection */ @Override public boolean remove(final Object object) { return remove(object, 1); } /** * (Change) * Remove all elements represented in the given collection, * not respecting cardinality. That is, remove all * occurrences of every object contained in the given collection. * * @param coll the collection to remove * @return true if this call changed the collection */ @Override public boolean removeAll(final Collection coll) { if (coll != null) { boolean result = false; final Iterator i = coll.iterator(); while (i.hasNext()) { final Object obj = i.next(); final boolean changed = remove(obj, getCount(obj)); result = result || changed; } return result; } // let the decorated bag handle the case of null argument return decorated().removeAll(null); } /** * (Change) * Remove any members of the bag that are not in the given collection, * not respecting cardinality. That is, any object in the given * collection coll will be retained in the bag with the same * number of copies prior to this operation. All other objects will be * completely removed from this bag. *

* This implementation iterates over the elements of this bag, checking * each element in turn to see if it's contained in coll. * If it's not contained, it's removed from this bag. As a consequence, * it is advised to use a collection type for coll that provides * a fast (e.g. O(1)) implementation of {@link Collection#contains(Object)}. * * @param coll the collection to retain * @return true if this call changed the collection */ @Override public boolean retainAll(final Collection coll) { if (coll != null) { boolean modified = false; final Iterator e = iterator(); while (e.hasNext()) { if (!coll.contains(e.next())) { e.remove(); modified = true; } } return modified; } // let the decorated bag handle the case of null argument return decorated().retainAll(null); } //----------------------------------------------------------------------- // Bag interface //----------------------------------------------------------------------- /** * (Change) * Adds count copies of the specified object to the Bag. *

* Since this method always increases the size of the bag, it * will always return true. * * @param object the object to add * @param count the number of copies to add * @return true, always */ @Override public boolean add(final E object, final int count) { decorated().add(object, count); return true; } }





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