import org.xml.sax.*;
import org.xml.sax.helpers.DefaultHandler;
import org.apache.xerces.parsers.SAXParser;

     class SaxParserGrades extends DefaultHandler
     {
        static float grades[][] = new float[100][5];
        int gi = -1;
        int nstudent = 0;
      
        public void startElement(String uri, String localName, String rawName,
                                 Attributes attributes)
        {
           if(localName.equals("hw1"))
              gi = 0;
           else if(localName.equals("hw2"))
              gi = 1;
           else if(localName.equals("project"))
              gi = 2;
           else if(localName.equals("final"))
              gi = 3;
           else if(localName.equals("student"))
           nstudent++;
        }

        public void endElement(String uri, String localName, String rawName)
        {
           gi = -1;
        }

        public void characters(char characters[], int start, int length)
        {
            String chData = (new String(characters, start,length)).trim();
            if(chData.indexOf("\n") < 0 && chData.length() > 0){
               if(gi >= 0){
                  grades[nstudent-1][gi] = Integer.parseInt(chData);
               }
            }
        }

        public void endDocument()
        {
           float Ave = 0;
           int i = 0, j = 0;
           System.out.println("Grades");
           for(i = 0; i < nstudent ; i++){
              float total = 0;
              for(j = 0; j < 4; j++){
                 total += grades[i][j];
              }           
              grades[i][4] = total/4;
              Ave += grades[i][4];
              System.out.println("Student " + i + "=" + grades[i][4]);
           }
           Ave /= nstudent;
           System.out.println("Class Average =" + Ave);
        }
     }

     public class SaxGrades 
     {
        public static void main(String[] args)
        {
           try{
              SaxParserGrades SAXHandler = new SaxParserGrades();
              SAXParser parser = new SAXParser();
              parser.setContentHandler(SAXHandler);
              parser.setErrorHandler(SAXHandler);
              parser.parse(args[0]);
        }
        catch(Exception e){
           e.printStackTrace(System.err);
        }
     }
  }


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<?xml version="1.0"?> 
     <course>
        <name id="csci_2962">Programming XML in Java</name>
        <teacher id="jp">
           <name>John Punin</name>
        </teacher>
        <student id="js">
           <name>John Smith</name>
           <hw1>30</hw1>
           <hw2>70</hw2>
           <project>80</project>
           <final>85</final>
        </student>
        <student id="gl">
           <name>George Lucas</name>
           <hw1>80</hw1>
           <hw2>90</hw2>
           <project>100</project>
           <final>40</final>
        </student>
        <student id="lr">
           <name>Elizabeth Roberts</name>
           <hw1>60</hw1>
           <hw2>95</hw2>
           <project>50</project>
           <final>90</final>
        </student>
     </course>