    001/*
    002 * Copyright 2013 The Apache Software Foundation.
    003 *
    004 * Licensed under the Apache License, Version 2.0 (the "License");
    005 * you may not use this file except in compliance with the License.
    006 * You may obtain a copy of the License at
    007 *
    008 *      http://www.apache.org/licenses/LICENSE-2.0
    009 *
    010 * Unless required by applicable law or agreed to in writing, software
    011 * distributed under the License is distributed on an "AS IS" BASIS,
    012 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
    013 * See the License for the specific language governing permissions and
    014 * limitations under the License.
    015 */
    016package org.apache.commons.collections4.iterators;
    017
    018import java.util.Iterator;
    019import java.util.NoSuchElementException;
    020
    021import org.w3c.dom.Node;
    022import org.w3c.dom.NodeList;
    023
    024/**
    025 * An {@link Iterator} over a {@link NodeList}.
    026 * <p>
    027 * This iterator does not support {@link #remove()} as a {@link NodeList} does not support
    028 * removal of items.
    029 *
    030 * @since 4.0
    031 * @see NodeList
    032 */
    033public class NodeListIterator implements Iterator<Node> {
    034
    035    /** the original NodeList instance */
    036    private final NodeList nodeList;
    037    /** The current iterator index */
    038    private int index = 0;
    039
    040    /**
    041     * Convenience constructor, which creates a new NodeListIterator from
    042     * the specified node's childNodes.
    043     *
    044     * @param node Node, who's child nodes are wrapped by this class. Must not be null
    045     * @throws NullPointerException if node is null
    046     */
    047    public NodeListIterator(final Node node) {
    048        if (node == null) {
    049            throw new NullPointerException("Node must not be null.");
    050        }
    051        this.nodeList = node.getChildNodes();
    052    }
    053
    054    /**
    055     * Constructor, that creates a new NodeListIterator from the specified
    056     * <code>org.w3c.NodeList</code>
    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        if (nodeList == null) {
    063            throw new NullPointerException("NodeList must not be null.");
    064        }
    065        this.nodeList = nodeList;
    066    }
    067
    068    @Override
    069    public boolean hasNext() {
    070        return nodeList != null && index < nodeList.getLength();
    071    }
    072
    073    @Override
    074    public Node next() {
    075        if (nodeList != null && index < nodeList.getLength()) {
    076            return nodeList.item(index++);
    077        }
    078        throw new NoSuchElementException("underlying nodeList has no more elements");
    079    }
    080
    081    /**
    082     * Throws {@link UnsupportedOperationException}.
    083     *
    084     * @throws UnsupportedOperationException always
    085     */
    086    @Override
    087    public void remove() {
    088        throw new UnsupportedOperationException("remove() method not supported for a NodeListIterator.");
    089    }
    090}