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The Apache PDFBox library is an open source Java tool for working with PDF documents.
/*
* 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.cos;
import java.io.IOException;
import java.io.OutputStream;
/**
* This class represents a null PDF object.
*
* @author Ben Litchfield
*/
public final class COSNull extends COSBase
{
/**
* The null token.
*/
public static final byte[] NULL_BYTES = new byte[] {110, 117, 108, 108}; //"null".getBytes( "ISO-8859-1" );
/**
* The one null object in the system.
*/
public static final COSNull NULL = new COSNull();
/**
* Constructor.
*/
private COSNull()
{
//limit creation to one instance.
}
/**
* visitor pattern double dispatch method.
*
* @param visitor The object to notify when visiting this object.
* @return any object, depending on the visitor implementation, or null
* @throws IOException If an error occurs while visiting this object.
*/
@Override
public Object accept( ICOSVisitor visitor ) throws IOException
{
return visitor.visitFromNull( this );
}
/**
* This will output this string as a PDF object.
*
* @param output The stream to write to.
* @throws IOException If there is an error writing to the stream.
*/
public void writePDF( OutputStream output ) throws IOException
{
output.write(NULL_BYTES);
}
/**
* {@inheritDoc}
*/
@Override
public String toString()
{
return "COSNull{}";
}
}