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.Iterator;
020import java.util.NoSuchElementException;
021import java.util.Objects;
022
023import org.w3c.dom.Node;
024import org.w3c.dom.NodeList;
025
026/**
027 * An {@link Iterator} over a {@link NodeList}.
028 * <p>
029 * This iterator does not support {@link #remove()} as a {@link NodeList} does not support
030 * removal of items.
031 * </p>
032 *
033 * @since 4.0
034 * @see NodeList
035 */
036public class NodeListIterator implements Iterator<Node> {
037
038    /** The original NodeList instance */
039    private final NodeList nodeList;
040    /** The current iterator index */
041    private int index;
042
043    /**
044     * Convenience constructor, which creates a new NodeListIterator from
045     * the specified node's childNodes.
046     *
047     * @param node Node, whose child nodes are wrapped by this class. Must not be null
048     * @throws NullPointerException if node is null
049     */
050    public NodeListIterator(final Node node) {
051        Objects.requireNonNull(node, "node");
052        this.nodeList = node.getChildNodes();
053    }
054
055    /**
056     * Constructor, that creates a new NodeListIterator from the specified
057     * {@code org.w3c.NodeList}
058     *
059     * @param nodeList node list, which is wrapped by this class. Must not be null
060     * @throws NullPointerException if nodeList is null
061     */
062    public NodeListIterator(final NodeList nodeList) {
063        this.nodeList = Objects.requireNonNull(nodeList, "nodeList");
064    }
065
066    @Override
067    public boolean hasNext() {
068        return nodeList != null && index < nodeList.getLength();
069    }
070
071    @Override
072    public Node next() {
073        if (nodeList != null && index < nodeList.getLength()) {
074            return nodeList.item(index++);
075        }
076        throw new NoSuchElementException("underlying nodeList has no more elements");
077    }
078
079    /**
080     * Throws {@link UnsupportedOperationException}.
081     *
082     * @throws UnsupportedOperationException always
083     */
084    @Override
085    public void remove() {
086        throw new UnsupportedOperationException("remove() method not supported for a NodeListIterator.");
087    }
088}