convert Object into a file using java

//Java
import java.io.File;
import java.io.IOException;
import java.io.InputStream;
import java.io.OutputStream;

import javax.xml.transform.Result;
import javax.xml.transform.Source;
import javax.xml.transform.Transformer;
import javax.xml.transform.TransformerException;
import javax.xml.transform.TransformerFactory;
import javax.xml.transform.sax.SAXResult;
import javax.xml.transform.sax.SAXSource;
import javax.xml.transform.stream.StreamSource;

import org.apache.avalon.framework.logger.ConsoleLogger;
import org.apache.avalon.framework.logger.Logger;
import org.apache.fop.apps.Driver;
import org.apache.fop.apps.FOPException;
import org.apache.fop.messaging.MessageHandler;
import org.xml.sax.InputSource;
import org.xml.sax.XMLReader;

/**
 * This class demonstrates the conversion of an arbitrary object file to a
 * PDF using JAXP (XSLT) and FOP (XSL:FO).
 */
public class GenericPDFGenerator {
   
    /*
     * This method accepts a list SavedReportResult objects, an xsl file to transform
     * and destination output stream
     */
    public void convert2PDF(InputSource inputSource, XMLReader xmlReader, InputStream xsltInputStream, OutputStream out)
                throws IOException, FOPException, TransformerException {

        //Construct driver
        Driver driver = new Driver();

        //Setup logger
        Logger logger = new ConsoleLogger(ConsoleLogger.LEVEL_INFO);
        driver.setLogger(logger);
        MessageHandler.setScreenLogger(logger);

        //Setup Renderer (output format)
        driver.setRenderer(Driver.RENDER_PDF);


        try {
            driver.setOutputStream(out);

            //Setup XSLT
            TransformerFactory factory = TransformerFactory.newInstance();
            Transformer transformer = factory.newTransformer(new StreamSource(xsltInputStream));

            //Setup input for XSLT transformation
            Source src = new SAXSource(xmlReader, inputSource);

            //Resulting SAX events (the generated FO) must be piped through to FOP
            Result res = new SAXResult(driver.getContentHandler());

            //Start XSLT transformation and FOP processing
            transformer.transform(src, res);
        } finally {
            out.close();
        }
    }
}