    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 *      https://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
    041    /** The current iterator index */
    042    private int index;
    043
    044    /**
    045     * Convenience constructor, which creates a new NodeListIterator from
    046     * the specified node's childNodes.
    047     *
    048     * @param node Node, whose child nodes are wrapped by this class. Must not be null
    049     * @throws NullPointerException if node is null
    050     */
    051    public NodeListIterator(final Node node) {
    052        Objects.requireNonNull(node, "node");
    053        this.nodeList = node.getChildNodes();
    054    }
    055
    056    /**
    057     * Constructor, that creates a new NodeListIterator from the specified
    058     * {@code org.w3c.NodeList}
    059     *
    060     * @param nodeList node list, which is wrapped by this class. Must not be null
    061     * @throws NullPointerException if nodeList is null
    062     */
    063    public NodeListIterator(final NodeList nodeList) {
    064        this.nodeList = Objects.requireNonNull(nodeList, "nodeList");
    065    }
    066
    067    @Override
    068    public boolean hasNext() {
    069        return nodeList != null && index < nodeList.getLength();
    070    }
    071
    072    @Override
    073    public Node next() {
    074        if (nodeList != null && index < nodeList.getLength()) {
    075            return nodeList.item(index++);
    076        }
    077        throw new NoSuchElementException("underlying nodeList has no more elements");
    078    }
    079
    080    /**
    081     * Always throws {@link UnsupportedOperationException}.
    082     *
    083     * @throws UnsupportedOperationException Always thrown.
    084     */
    085    @Override
    086    public void remove() {
    087        throw new UnsupportedOperationException("remove() method not supported for a NodeListIterator.");
    088    }
    089}