SAXBuilder builder=new SAXBuilder(false);
      
        Document doc=builder.build("file.xml");
      
       Element raiz=doc.getRootElement();

        List chapter=raiz.getChildren("CHAPTER");
        Iterator i = chapter.iterator();
        while (i.hasNext()){
            Element e= (Element)i.next();

             Element section =e.getChild("SECTION");
             List sectionHijos=e.getChildren("SECTION");

         XMLOutputter out = new XMLOutputter();
          FileWriter writer = new FileWriter("TestVarios2.xml");
           out.output(section,writer);
            writer.flush();
             writer.close();

example :

out.output(sectionHijos,writer)

                      |--------------------------------------->failed