# PDOutlineItemIterator.java

    /*
     * Licensed to the Apache Software Foundation (ASF) under one or more
     * contributor license agreements.  See the NOTICE file distributed with
     * this work for additional information regarding copyright ownership.
     * The ASF licenses this file to You under the Apache License, Version 2.0
     * (the "License"); you may not use this file except in compliance with
     * the License.  You may obtain a copy of the License at
     *
     *      http://www.apache.org/licenses/LICENSE-2.0
     *
     * Unless required by applicable law or agreed to in writing, software
     * distributed under the License is distributed on an "AS IS" BASIS,
     * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
     * See the License for the specific language governing permissions and
     * limitations under the License.
     */
    package org.apache.pdfbox.pdmodel.interactive.documentnavigation.outline;

    import java.util.Iterator;
    import java.util.NoSuchElementException;

    /**
     * Iterator over the linked list of {@link PDOutlineItem} siblings.
     *
     * @author Andrea Vacondio
     *
     */
    class PDOutlineItemIterator implements Iterator<PDOutlineItem>
    {
        private PDOutlineItem currentItem;
        private final PDOutlineItem startingItem;

        PDOutlineItemIterator(PDOutlineItem startingItem)
        {
            this.startingItem = startingItem;
        }

        @Override
        public boolean hasNext()
        {
            if (startingItem == null)
            {
                return false;
            }
            if (currentItem == null)
            {
                return true;
            }
            PDOutlineItem sibling = currentItem.getNextSibling();
            return sibling != null && !startingItem.equals(sibling);
        }

        @Override
        public PDOutlineItem next()
        {
            if (!hasNext())
            {
                throw new NoSuchElementException();
            }
            if (currentItem == null)
            {
                currentItem = startingItem;
            }
            else
            {
                currentItem = currentItem.getNextSibling();
            }
            return currentItem;
        }

        @Override
        public void remove()
        {
            throw new UnsupportedOperationException();
        }
    }