/* a dom parser that displays only element tags */
import javax.xml.parsers.*; 
import org.xml.sax.*;
import java.io.*;
import org.w3c.dom.*;
import java.lang.String;

public class DomParser1{
    public static void main(String argv[])
    {
        if (argv.length != 1) {
            System.err.println("Usage: java DomParser filename");
            System.exit(1);
        }
        DocumentBuilderFactory factory =
            DocumentBuilderFactory.newInstance();
	// factory.setValidating(true);   
	// factory.setNamespaceAware(true);
        try {
           DocumentBuilder builder = factory.newDocumentBuilder();
           Document document = builder.parse( new File(argv[0]) );
	   // this could also read from a URL or any other stream
           Element root = document.getDocumentElement();
           if (root != null) PrintTree(root,0);
        } catch (SAXException sxe) {
           // Error generated during parsing)
           Exception  x = sxe;
           if (sxe.getException() != null)
               x = sxe.getException();
           x.printStackTrace();

        } catch (ParserConfigurationException pce) {
            // Parser with specified options can't be built
            pce.printStackTrace();

        } catch (IOException ioe) {
           // I/O error
           ioe.printStackTrace();
        }
    } // end of main

    // PrintTree - prints the dom tree, indenting each level 
    //    an additional 4 spaces
    private static void PrintTree(Element e, int indent) 
    {
        String s = e.getTagName();
        int i;
        for (i=0;i<indent;i++) System.out.print(" ");
        System.out.println(s);
        Node child = e.getFirstChild();
        while (child != null) {
	    if (child instanceof Element)  // ignores whitespaces 
                   PrintTree((Element)child,indent+4);
	    child = child.getNextSibling();
	}
    }
}
/****************
java DomParser book.xml
book
    title
    author
        lastname
        firstname
    date
    chapter
        chaptertitle
        para
        para
    chapter
        chaptertitle
        para
        para
        para
        para
***********/