001/*
002 * Licensed to the Apache Software Foundation (ASF) under one or more
003 * contributor license agreements.  See the NOTICE file distributed with
004 * this work for additional information regarding copyright ownership.
005 * The ASF licenses this file to You under the Apache License, Version 2.0
006 * (the "License"); you may not use this file except in compliance with
007 * the License.  You may obtain a copy of the License at
008 *
009 *      http://www.apache.org/licenses/LICENSE-2.0
010 *
011 * Unless required by applicable law or agreed to in writing, software
012 * distributed under the License is distributed on an "AS IS" BASIS,
013 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
014 * See the License for the specific language governing permissions and
015 * limitations under the License.
016 */
017package org.apache.commons.collections4.bag;
018
019import java.io.IOException;
020import java.io.ObjectInputStream;
021import java.io.ObjectOutputStream;
022import java.io.Serializable;
023import java.util.Collection;
024import java.util.Comparator;
025import java.util.Objects;
026import java.util.SortedMap;
027import java.util.TreeMap;
028
029import org.apache.commons.collections4.SortedBag;
030
031/**
032 * Implements {@link SortedBag}, using a {@link TreeMap} to provide the data storage.
033 * This is the standard implementation of a sorted bag.
034 * <p>
035 * Order will be maintained among the bag members and can be viewed through the iterator.
036 * </p>
037 * <p>
038 * A {@link org.apache.commons.collections4.Bag Bag} stores each object in the collection
039 * together with a count of occurrences. Extra methods on the interface allow multiple
040 * copies of an object to be added or removed at once. It is important to read the interface
041 * Javadoc carefully as several methods violate the {@link Collection} interface specification.
042 * </p>
043 *
044 * @param <E> the type of elements in this bag
045 * @since 3.0 (previously in main package v2.0)
046 */
047public class TreeBag<E> extends AbstractMapBag<E> implements SortedBag<E>, Serializable {
048
049    /** Serial version lock */
050    private static final long serialVersionUID = -7740146511091606676L;
051
052    /**
053     * Constructs an empty {@link TreeBag}.
054     */
055    public TreeBag() {
056        super(new TreeMap<>());
057    }
058
059    /**
060     * Constructs a {@link TreeBag} containing all the members of the
061     * specified collection.
062     *
063     * @param coll the collection to copy into the bag
064     */
065    public TreeBag(final Collection<? extends E> coll) {
066        this();
067        addAll(coll);
068    }
069
070    /**
071     * Constructs an empty bag that maintains order on its unique representative
072     * members according to the given {@link Comparator}.
073     *
074     * @param comparator the comparator to use
075     */
076    public TreeBag(final Comparator<? super E> comparator) {
077        super(new TreeMap<>(comparator));
078    }
079
080    /**
081     * Constructs a bag containing all the members of the given Iterable.
082     *
083     * @param iterable an iterable to copy into this bag.
084     * @since 4.5.0-M3
085     */
086    public TreeBag(final Iterable<? extends E> iterable) {
087        super(new TreeMap<>(), iterable);
088    }
089
090    /**
091     * {@inheritDoc}
092     *
093     * @throws IllegalArgumentException if the object to be added does not implement
094     * {@link Comparable} and the {@link TreeBag} is using natural ordering
095     * @throws NullPointerException if the specified key is null and this bag uses
096     * natural ordering, or its comparator does not permit null keys
097     */
098    @Override
099    public boolean add(final E object) {
100        if (comparator() == null && !(object instanceof Comparable)) {
101            Objects.requireNonNull(object, "object");
102            throw new IllegalArgumentException("Objects of type " + object.getClass() + " cannot be added to " +
103                                               "a naturally ordered TreeBag as it does not implement Comparable");
104        }
105        return super.add(object);
106    }
107
108    @Override
109    public Comparator<? super E> comparator() {
110        return getMap().comparator();
111    }
112
113    @Override
114    public E first() {
115        return getMap().firstKey();
116    }
117
118    @Override
119    protected SortedMap<E, AbstractMapBag.MutableInteger> getMap() {
120        return (SortedMap<E, AbstractMapBag.MutableInteger>) super.getMap();
121    }
122
123    @Override
124    public E last() {
125        return getMap().lastKey();
126    }
127
128    /**
129     * Deserializes the bag in using a custom routine.
130     *
131     * @param in  the input stream
132     * @throws IOException if an error occurs while reading from the stream
133     * @throws ClassNotFoundException if an object read from the stream cannot be loaded
134     */
135    private void readObject(final ObjectInputStream in) throws IOException, ClassNotFoundException {
136        in.defaultReadObject();
137        @SuppressWarnings("unchecked")  // This will fail at runtime if the stream is incorrect
138        final Comparator<? super E> comp = (Comparator<? super E>) in.readObject();
139        super.doReadObject(new TreeMap<>(comp), in);
140    }
141
142    /**
143     * Serializes this object to an ObjectOutputStream.
144     *
145     * @param out the target ObjectOutputStream.
146     * @throws IOException thrown when an I/O errors occur writing to the target stream.
147     */
148    private void writeObject(final ObjectOutputStream out) throws IOException {
149        out.defaultWriteObject();
150        out.writeObject(comparator());
151        super.doWriteObject(out);
152    }
153
154}