Creating DOMParser and Document

   import org.w3c.dom.*;
   import org.apache.xerces.parsers.DOMParser;

   class Grades
   { 
      public static void computeGrades(String uri)
      {
         try{
            DOMParser parser = new DOMParser();
            parser.parse(uri);
            Document doc = parser.getDocument();
            traverse_tree(doc);
            compute_final_grades();
         } 
	 catch(Exception e){
            e.printStackTrace(System.err);
         }
      }
      .
      .
      .
   }

   public class DOMGrades
   {   
      public static void main(String[] args)
      {
         Grades.computeGrades(args[0]);
      }
   }