    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}