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