XMLBeautifier

import java.io.ByteArrayInputStream;

import javax.xml.parsers.DocumentBuilderFactory;

import org.w3c.dom.Node;
import org.w3c.dom.bootstrap.DOMImplementationRegistry;
import org.w3c.dom.ls.DOMImplementationLS;
import org.w3c.dom.ls.LSSerializer;

public class XMLBeautifier {
   Node document;
   boolean keepDeclaration;

   public XMLBeautifier(String xml) {
      try {
         this.document = DocumentBuilderFactory.newInstance().newDocumentBuilder().parse(new ByteArrayInputStream(xml.getBytes())).getDocumentElement();
         this.keepDeclaration = xml.startsWith("<?xml");
      } catch (Exception e) {
         e.printStackTrace();
      }
   }

   public String getXML() {
      try {
         DOMImplementationRegistry registry = DOMImplementationRegistry.newInstance();
         DOMImplementationLS impl = (DOMImplementationLS)registry.getDOMImplementation("LS");
         LSSerializer writer = impl.createLSSerializer();

         writer.getDomConfig().setParameter("format-pretty-print", true); // Set this to true if the output needs to be beautified.
         writer.getDomConfig().setParameter("xml-declaration", keepDeclaration); // Set this to true if the declaration is needed to be outputted.

         return writer.writeToString(document);
      } catch (Exception e) {
         e.printStackTrace();
         return null;
      }
   }

   public static void main(String[] args) {
      String xml = "<shiporder orderid=\"889923\" xmlns:xsi=\"http://www.w3.org/2001/XMLSchema-instance\" xsi:noNamespaceSchemaLocation=\"shiporder.xsd\"><orderperson>John Smith</orderperson><shipto><name>Ola Nordmann</name><address>Langgt 23</address><city>4000 Stavanger</city><country>Norway</country></shipto><item><title>Empire Burlesque</title><note>Special Edition</note><quantity>1</quantity><price>10.90</price></item><item><title>Hide your heart</title><quantity>1</quantity><price>9.90</price></item></shiporder>";

      System.out.println(new XMLBeautifier(xml).getXML());
   }
}

------------------------ CONSOLE -------------------------
<shiporder orderid="889923" xmlns:xsi="w3.org/2001/XMLSchema-instance" xsi:noNamespaceSchemaLocation="shiporder.xsd">
    <orderperson>John Smith</orderperson>
    <shipto>
        <name>Ola Nordmann</name>
        <address>Langgt 23</address>
        <city>4000 Stavanger</city>
        <country>Norway</country>
    </shipto>
    <item>
        <title>Empire Burlesque</title>
        <note>Special Edition</note>
        <quantity>1</quantity>
        <price>10.90</price>
    </item>
    <item>
        <title>Hide your heart</title>
        <quantity>1</quantity>
        <price>9.90</price>
    </item>
</shiporder>