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.iterators;
018
019import java.util.Enumeration;
020import java.util.Iterator;
021
022/**
023 * Adapter to make an {@link Iterator Iterator} instance appear to be an
024 * {@link Enumeration Enumeration} instance.
025 *
026 * @param <E> the type of elements returned by this iterator.
027 * @since 1.0
028 */
029public class IteratorEnumeration<E> implements Enumeration<E> {
030
031    /** The iterator being decorated. */
032    private Iterator<? extends E> iterator;
033
034    /**
035     * Constructs a new {@code IteratorEnumeration} that will not function
036     * until {@link #setIterator(Iterator) setIterator} is invoked.
037     */
038    public IteratorEnumeration() {
039    }
040
041    /**
042     * Constructs a new {@code IteratorEnumeration} that will use the given
043     * iterator.
044     *
045     * @param iterator the iterator to use
046     */
047    public IteratorEnumeration(final Iterator<? extends E> iterator) {
048        this.iterator = iterator;
049    }
050
051    /**
052     * Returns the underlying iterator.
053     *
054     * @return the underlying iterator
055     */
056    public Iterator<? extends E> getIterator() {
057        return iterator;
058    }
059
060    /**
061     * Returns true if the underlying iterator has more elements.
062     *
063     * @return true if the underlying iterator has more elements
064     */
065    @Override
066    public boolean hasMoreElements() {
067        return iterator.hasNext();
068    }
069
070    /**
071     * Returns the next element from the underlying iterator.
072     *
073     * @return the next element from the underlying iterator.
074     * @throws java.util.NoSuchElementException if the underlying iterator has
075     * no more elements
076     */
077    @Override
078    public E nextElement() {
079        return iterator.next();
080    }
081
082    /**
083     * Sets the underlying iterator.
084     *
085     * @param iterator the new underlying iterator
086     */
087    public void setIterator(final Iterator<? extends E> iterator) {
088        this.iterator = iterator;
089    }
090
091}