import org.jdom.Document;
import org.jdom.Element;
import org.jdom.JDOMException;
import org.jdom.input.SAXBuilder;
import org.jdom.output.XMLOutputter;

import org.xml.sax.EntityResolver;
import org.xml.sax.InputSource;
import org.xml.sax.SAXException;

import java.io.IOException;
import java.io.InputStream;
import java.io.ByteArrayInputStream;

import java.util.Collections;
import java.util.Comparator;
import java.util.Iterator;

class JdomSort
{
    public static void main(String[] args)
        throws IOException, JDOMException
    {
        String xml =
            "<?xml version=\"1.0\"?>" +
            "<root>" +
            "   <elem1><a/><b/><c/></elem1>" +
            "   <elem2><c/><a/><b/></elem2>" +
            "   <elem1><a/><b/><c/></elem1>" +
            "</root>";
        InputStream input = new ByteArrayInputStream(xml.getBytes());
        SAXBuilder builder = new SAXBuilder(false);
        Document doc = builder.build(input);
        
        String[] rootOrder = {"elem1", "elem2"};
        String[] elem1Order = {"c", "a", "b"};
        String[] elem2Order = {"a", "b", "c"};
        
System.out.println("Starting to sort...");

        Element root = doc.getRootElement();
        Collections.sort(root.getChildren(), new ElementSorter(rootOrder));
        
        Iterator iter = root.getChildren("elem1").iterator();
        while (iter.hasNext())
        {
            Element elem = (Element) iter.next();
            Collections.sort(elem.getChildren(), new ElementSorter(elem1Order));
        }
        
        iter = root.getChildren("elem2").iterator();
        while (iter.hasNext())
        {
            Element elem = (Element) iter.next();
            Collections.sort(elem.getChildren(), new ElementSorter(elem2Order));
        }
        
        XMLOutputter out = new XMLOutputter("   ", true);
        out.output(doc, System.out);
    }
}

class ElementSorter implements Comparator
{
    private String[] order;
    
    public ElementSorter(String[] order)
    {
        this.order = order;
    }
    
    public int compare(Object o1, Object o2)
    {
        Element e1 = (Element) o1;
        Element e2 = (Element) o2;
        int index1 = indexOf(e1);
        int index2 = indexOf(e2);
        
System.out.println("Comparing " + e1.getName() + " to " + e2.getName() + "; returning " + (index1 - index2));        
        return index1 - index2;
    }
    
    private int indexOf(Element e)
    {
        String name = e.getName();
        for (int i = 0; i < order.length; i++)
        {
            if (order[i].equals(name))
            {
                return i;
            }   
        }
        
        return -1;
    }
}