Here is a more elegant way to serialize an xml dom to file in Java than using a Transformer. I've heard that LSSerializer also out-performs the usual Transformer approach, but I haven't verified this so far. The source code is HERE.

import org.w3c.dom.Document;
import org.w3c.dom.Node;
import org.w3c.dom.ls.DOMImplementationLS;
import org.w3c.dom.ls.LSOutput;
import org.w3c.dom.ls.LSSerializer;

import java.io.FileWriter;
import java.io.IOException;
import java.io.Writer;

import java.util.Scanner;

import javax.xml.parsers.DocumentBuilderFactory;


public class XmlSerializer {
    public static void main(String[] args) throws Exception {
        String xml = "ROOT(PARAMS,PARAM1,PARAM2,PARAM3)";
        Scanner s = new Scanner(xml);
        s.useDelimiter("[(),\\s]");

        Document doc = DocumentBuilderFactory.newInstance().newDocumentBuilder()
                                             .newDocument();

        Node root = doc.createElement(s.next());
        doc.appendChild(root);

        Node sheet = doc.createElement(s.next());
        root.appendChild(sheet);

        while (s.hasNext()) {
            Node param = doc.createElement(s.next());
            sheet.appendChild(param);
        }

        // Serialize to file in current directory
        XmlSerializer.saveToFile(doc, "x.xml");
    }

    /**
     *
     @param doc The Document to serialize to String
     * @param fileName The file path to which to write
     */

    public static void saveToFile(Document doc, String fileName) {
        FileWriter out = null;

        try {
            DOMImplementationLS domImplementation = (DOMImplementationLS) doc.getImplementation();
            LSSerializer lsSerializer = domImplementation.createLSSerializer();
            lsSerializer.getDomConfig()
                        .setParameter("format-pretty-print", Boolean.TRUE);

            LSOutput output = domImplementation.createLSOutput();
            output.setEncoding(System.getProperty("file.encoding"));
            out = new FileWriter(fileName);
            output.setCharacterStream(out);
            lsSerializer.write(doc, output);
        } catch (IOException e) {
            e.printStackTrace();
        } finally {
            if (out != null) {
                try {
                    out.close();
                } catch (IOException e) { /* ignore */
                }
            }
        }
    }
}