# PDThread.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.pagenavigation;

    import org.apache.pdfbox.cos.COSDictionary;
    import org.apache.pdfbox.cos.COSName;
    import org.apache.pdfbox.pdmodel.PDDocumentInformation;
    import org.apache.pdfbox.pdmodel.common.COSObjectable;

    /**
     * This a single thread in a PDF document.
     *
     * @author Ben Litchfield
     */
    public class PDThread implements COSObjectable
    {

        private final COSDictionary thread;

        /**
         * Constructor that is used for a preexisting dictionary.
         *
         * @param t The underlying dictionary.
         */
        public PDThread( COSDictionary t )
        {
            thread = t;
        }

        /**
         * Default constructor.
         *
         */
        public PDThread()
        {
            thread = new COSDictionary();
            thread.setItem(COSName.TYPE, COSName.THREAD);
        }

        /**
         * This will get the underlying dictionary that this object wraps.
         *
         * @return The underlying info dictionary.
         */
        @Override
        public COSDictionary getCOSObject()
        {
            return thread;
        }

        /**
         * Get info about the thread, or null if there is nothing.
         *
         * @return The thread information.
         */
        public PDDocumentInformation getThreadInfo()
        {
            COSDictionary info = thread.getCOSDictionary(COSName.I);
            return info != null ? new PDDocumentInformation(info) : null;
        }

        /**
         * Set the thread info, can be null.
         *
         * @param info The info dictionary about this thread.
         */
        public void setThreadInfo( PDDocumentInformation info )
        {
            thread.setItem(COSName.I, info);
        }

        /**
         * Get the first bead in the thread, or null if it has not been set yet.  This
         * is a required field for this object.
         *
         * @return The first bead in the thread.
         */
        public PDThreadBead getFirstBead()
        {
            COSDictionary bead = thread.getCOSDictionary(COSName.F);
            return bead != null ? new PDThreadBead(bead) : null;
        }

        /**
         * This will set the first bead in the thread.  When this is set it will
         * also set the thread property of the bead object.
         *
         * @param bead The first bead in the thread.
         */
        public void setFirstBead( PDThreadBead bead )
        {
            if( bead != null )
            {
                bead.setThread( this );
            }
            thread.setItem(COSName.F, bead);
        }

    }