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}