Output DOM tree by node type in Java

import java.io.IOException;
import java.io.StringReader;
//ww w  . java2  s .c  om
import javax.xml.parsers.DocumentBuilder;
import javax.xml.parsers.DocumentBuilderFactory;

import org.w3c.dom.Attr;
import org.w3c.dom.CDATASection;
import org.w3c.dom.Comment;
import org.w3c.dom.Document;
import org.w3c.dom.DocumentType;
import org.w3c.dom.Element;
import org.w3c.dom.NamedNodeMap;
import org.w3c.dom.Node;
import org.w3c.dom.NodeList;
import org.w3c.dom.ProcessingInstruction;
import org.w3c.dom.Text;
import org.xml.sax.ErrorHandler;
import org.xml.sax.InputSource;
import org.xml.sax.SAXException;
import org.xml.sax.SAXParseException;

public class Main {
  static public void main(String[] arg) throws Exception {
    DocumentBuilderFactory dbf = DocumentBuilderFactory.newInstance();
    dbf.setValidating(true);
    dbf.setNamespaceAware(true);
    dbf.setIgnoringElementContentWhitespace(true);

    DocumentBuilder builder = dbf.newDocumentBuilder();
    builder.setErrorHandler(new MyErrorHandler());

    StringReader sr = new StringReader("<tag>java2s.com</tag>");
    Document document = builder.parse(new InputSource(sr));

    write(document);

  }

  private static final String TAB = "    ";

  private static void write(Document doc) throws IOException {
    outputHeading(doc);
    outputElement(doc.getDocumentElement(), "");
  }

  private static void outputHeading(Document doc) {
    System.out.print("<?xml version=\"1.0\"");
    DocumentType doctype = doc.getDoctype();
    if (doctype != null) {
      if ((doctype.getPublicId() == null) && (doctype.getSystemId() == null)) {
        System.out.println(" standalone=\"yes\"?>");
      } else {
        System.out.println(" standalone=\"no\"?>");
      }
    } else {
      System.out.println("?>");
    }
  }

  private static void outputElement(Element node, String indent) {
    System.out.print(indent + "<" + node.getTagName());
    NamedNodeMap nm = node.getAttributes();
    for (int i = 0; i < nm.getLength(); i++) {
      Attr attr = (Attr) nm.item(i);
      System.out.print(" " + attr.getName() + "=\"" + attr.getValue() + "\"");
    }
    System.out.println(">");
    NodeList list = node.getChildNodes();
    for (int i = 0; i < list.getLength(); i++)
      outputloop(list.item(i), indent + TAB);
    System.out.println(indent + "</" + node.getTagName() + ">");
  }

  private static void outputText(Text node, String indent) {
    System.out.println(indent + node.getData());
  }

  private static void outputCDATASection(CDATASection node, String indent) {
    System.out.println(indent + node.getData());
  }

  private static void outputComment(Comment node, String indent) {
    System.out.println(indent + "<!-- " + node.getData() + " -->");
  }

  private static void outputProcessingInstructionNode(
      ProcessingInstruction node, String indent) {
    System.out.println(indent + "<?" + node.getTarget() + " " + node.getData()
        + "?>");
  }

  private static void outputloop(Node node, String indent) {
    switch (node.getNodeType()) {
    case Node.ELEMENT_NODE:
      outputElement((Element) node, indent);
      break;
    case Node.TEXT_NODE:
      outputText((Text) node, indent);
      break;
    case Node.CDATA_SECTION_NODE:
      outputCDATASection((CDATASection) node, indent);
      break;
    case Node.COMMENT_NODE:
      outputComment((Comment) node, indent);
      break;
    case Node.PROCESSING_INSTRUCTION_NODE:
      outputProcessingInstructionNode((ProcessingInstruction) node, indent);
      break;
    default:
      System.out.println("Unknown node type: " + node.getNodeType());
      break;
    }
  }
}

class MyErrorHandler implements ErrorHandler {
  public void warning(SAXParseException e) throws SAXException {
    show("Warning", e);
    throw (e);
  }

  public void error(SAXParseException e) throws SAXException {
    show("Error", e);
    throw (e);
  }

  public void fatalError(SAXParseException e) throws SAXException {
    show("Fatal Error", e);
    throw (e);
  }

  private void show(String type, SAXParseException e) {
    System.out.println(type + ": " + e.getMessage());
    System.out.println("Line " + e.getLineNumber() + " Column "
        + e.getColumnNumber());
    System.out.println("System ID: " + e.getSystemId());
  }
}