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}