java dom tree

import java.io.File;
import java.io.FileWriter;

import javax.xml.parsers.DocumentBuilder;
import javax.xml.parsers.DocumentBuilderFactory;

import org.apache.crimson.tree.XmlDocument;

import org.w3c.dom.Document;
import org.w3c.dom.Element;
import org.w3c.dom.Node;

public class MyTree {

	private static String line = "--";
	private static int count = 0;

	public static void main(String[] args) throws Exception {

		DocumentBuilderFactory dbFactory = DocumentBuilderFactory.newInstance();
		DocumentBuilder dbBuilder = dbFactory.newDocumentBuilder();
		Document doc = dbBuilder.newDocument(); // file
		Element rootDirElement = null;
		if (doc != null) {

			File dir = new File("D:\\tree");
			rootDirElement = doc.createElement(dir.getName());
			// System.out.println(line+dir.getName());
			indexDoc(doc, rootDirElement, dir);
			doc.appendChild(rootDirElement);
			// crimson-1.1.3.jar
			((XmlDocument) doc).write(new FileWriter("src/result.xml"));
			traver(doc.getFirstChild());

		}

	}

	public static void traver(Node node) {
		
		System.out.println(getLine()+node.getNodeName());
		Node child = node.getFirstChild();
		while (child != null) {
			
			traver(child);
			//count--;
			child = child.getNextSibling();
			
		}
		count++;
	}

	private static void indexDoc(Document doc, Element lastElement, File dir) {
		
		for (File file : dir.listFiles()) {
			if (file.isDirectory()) {

				Element fileElement = doc.createElement(file.getName());
				lastElement.appendChild(fileElement);
				// System.out.println(getLine()+file.getName());
				indexDoc(doc, fileElement, file);
			} else {

				Element fileElement = doc.createElement(file.getName());
				lastElement.appendChild(fileElement);
				// count--;
				// System.out.println(getLine()+file.getName());
			}

		}

	}

	private static String getLine() {
		String line = "";
		for (int i = 0; i < count; i++) {
			line = line + "--";
		}
		return line;
	}

}