001/*
002 * $Id: PdfNull.java 4784 2011-03-15 08:33:00Z blowagie $
003 *
004 * This file is part of the iText (R) project.
005 * Copyright (c) 1998-2011 1T3XT BVBA
006 * Authors: Bruno Lowagie, Paulo Soares, et al.
007 *
008 * This program is free software; you can redistribute it and/or modify
009 * it under the terms of the GNU Affero General Public License version 3
010 * as published by the Free Software Foundation with the addition of the
011 * following permission added to Section 15 as permitted in Section 7(a):
012 * FOR ANY PART OF THE COVERED WORK IN WHICH THE COPYRIGHT IS OWNED BY 1T3XT,
013 * 1T3XT DISCLAIMS THE WARRANTY OF NON INFRINGEMENT OF THIRD PARTY RIGHTS.
014 *
015 * This program is distributed in the hope that it will be useful, but
016 * WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY
017 * or FITNESS FOR A PARTICULAR PURPOSE.
018 * See the GNU Affero General Public License for more details.
019 * You should have received a copy of the GNU Affero General Public License
020 * along with this program; if not, see http://www.gnu.org/licenses or write to
021 * the Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor,
022 * Boston, MA, 02110-1301 USA, or download the license from the following URL:
023 * http://itextpdf.com/terms-of-use/
024 *
025 * The interactive user interfaces in modified source and object code versions
026 * of this program must display Appropriate Legal Notices, as required under
027 * Section 5 of the GNU Affero General Public License.
028 *
029 * In accordance with Section 7(b) of the GNU Affero General Public License,
030 * a covered work must retain the producer line in every PDF that is created
031 * or manipulated using iText.
032 *
033 * You can be released from the requirements of the license by purchasing
034 * a commercial license. Buying such a license is mandatory as soon as you
035 * develop commercial activities involving the iText software without
036 * disclosing the source code of your own applications.
037 * These activities include: offering paid services to customers as an ASP,
038 * serving PDFs on the fly in a web application, shipping iText with a closed
039 * source product.
040 *
041 * For more information, please contact iText Software Corp. at this
042 * address: sales@itextpdf.com
043 */
044package com.itextpdf.text.pdf;
045
046/**
047 * <CODE>PdfNull</CODE> is the Null object represented by the keyword <VAR>null</VAR>.
048 * <P>
049 * This object is described in the 'Portable Document Format Reference Manual version 1.7'
050 * section 3.2.8 (page 63).
051 *
052 * @see         PdfObject
053 */
054
055public class PdfNull extends PdfObject {
056    
057    // CLASS CONSTANTS
058    
059    /** An instance of the <CODE>PdfNull</CODE>-object. */
060    public static final PdfNull PDFNULL = new PdfNull();
061    
062    /** The content of the <CODE>PdfNull</CODE>-object. */
063    private static final String CONTENT = "null";
064    
065    // CONSTRUCTOR
066    
067    /**
068     * Constructs a <CODE>PdfNull</CODE>-object.
069     * <P>
070     * You never need to do this yourself, you can always use the static final object <VAR>PDFNULL</VAR>.
071     */
072    public PdfNull() {
073        super(NULL, CONTENT);
074    }
075    
076    // CLASS METHOD
077    
078    public String toString() {
079        return "null";
080    }
081}