Example: IDTagger

import java.io.IOException;
import nu.xom.*;

public class IDTagger {

  private static int id = 1;

  public static void processElement(Element element) {
    
    if (element.getAttribute("ID") == null) {
      element.addAttribute(new Attribute("ID", "_" + id));
      id = id + 1; 
    }
    
    // recursion
    Elements children = element.getChildElements();
    for (int i = 0; i < children.size(); i++) {
      processElement(children.get(i));   
    }
    
  }

  public static void main(String[] args) {
     
    Builder builder = new Builder();
    
    for (int i = 0; i < args.length; i++) {
        
      try {
        // Read the entire document into memory
        Document document = builder.build(args[i]); 
       
        processElement(document.getRootElement());
        
        System.out.println(document.toXML());         
      }
      catch (ParsingException ex) {
        System.err.println(ex);
        continue; 
      }
      catch (IOException ex) {
        System.err.println(ex);
        continue; 
      }
      
    }
  
  } // end main

}