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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.io.Serializable;
import java.util.Collection;
import java.util.Comparator;
import java.util.SortedMap;
import java.util.TreeMap;

import org.apache.commons.collections4.SortedBag;

/**
 * Implements {@link SortedBag}, using a {@link TreeMap} to provide the data storage.
 * This is the standard implementation of a sorted bag.
 * 

* Order will be maintained among the bag members and can be viewed through the iterator. *

* A {@link org.apache.commons.collections4.Bag Bag} stores each object in the collection * together with a count of occurrences. Extra methods on the interface allow multiple * copies of an object to be added or removed at once. It is important to read the interface * javadoc carefully as several methods violate the {@link Collection} interface specification. * * @param the type of elements in this bag * @since 3.0 (previously in main package v2.0) */ public class TreeBag extends AbstractMapBag implements SortedBag, Serializable { /** Serial version lock */ private static final long serialVersionUID = -7740146511091606676L; /** * Constructs an empty {@link TreeBag}. */ public TreeBag() { super(new TreeMap()); } /** * Constructs an empty bag that maintains order on its unique representative * members according to the given {@link Comparator}. * * @param comparator the comparator to use */ public TreeBag(final Comparator comparator) { super(new TreeMap(comparator)); } /** * Constructs a {@link TreeBag} containing all the members of the * specified collection. * * @param coll the collection to copy into the bag */ public TreeBag(final Collection coll) { this(); addAll(coll); } //----------------------------------------------------------------------- /** * {@inheritDoc} * * @throws IllegalArgumentException if the object to be added does not implement * {@link Comparable} and the {@link TreeBag} is using natural ordering * @throws NullPointerException if the specified key is null and this bag uses * natural ordering, or its comparator does not permit null keys */ @Override public boolean add(final E object) { if(comparator() == null && !(object instanceof Comparable)) { if (object == null) { throw new NullPointerException(); } throw new IllegalArgumentException("Objects of type " + object.getClass() + " cannot be added to " + "a naturally ordered TreeBag as it does not implement Comparable"); } return super.add(object); } //----------------------------------------------------------------------- @Override public E first() { return getMap().firstKey(); } @Override public E last() { return getMap().lastKey(); } @Override public Comparator comparator() { return getMap().comparator(); } @Override protected SortedMap getMap() { return (SortedMap) super.getMap(); } //----------------------------------------------------------------------- /** * Write the bag 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(comparator()); super.doWriteObject(out); } /** * Read the bag 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 */ private void readObject(final ObjectInputStream in) throws IOException, ClassNotFoundException { in.defaultReadObject(); @SuppressWarnings("unchecked") // This will fail at runtime if the stream is incorrect final Comparator comp = (Comparator) in.readObject(); super.doReadObject(new TreeMap(comp), in); } }





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