DOMNewDoc.java - Building a New DOM Document

JDK Tutorials - Herong's Tutorial Examples

∟DOM (Document Object Model) - API for XML Files

∟DOMNewDoc.java - Building a New DOM Document

This section provides a tutorial example on how to write a program to create a new DOM document object with DOM classes and methods like: DocumentBuilder.newDocument(), Document.createElement(), Document.createTextNode(), and Node.appendChild().

DOM documents can also be created from scratch instead of parsed from an XML file. This can be easily done by using the following methods:

DocumentBuilder.newDocument(): Create an empty DOM document.
Document.createElement(): Create a new Element.
Document.createTextNode(): Create a new TextNode.
Node.appendChild(): Insert a sub Node into the current Node.
Element.setAttribute(): Add new attribute into an element.

The following program shows how to create a simple DOM document with these methods:

/* DOMNewDoc.java
 * Copyright (c) HerongYang.com. All Rights Reserved.
 */
import java.io.*;
import javax.xml.parsers.*;
import org.w3c.dom.*;
class DOMNewDoc {
   public static void main(String[] args) {
      try {
         DocumentBuilderFactory f
            = DocumentBuilderFactory.newInstance();
         DocumentBuilder b = f.newDocumentBuilder();
         Document d = b.newDocument();
         Element r = d.createElement("dictionary");
         d.appendChild(r);
         Element w = d.createElement("word");
         r.appendChild(w);
         Element e = d.createElement("update");
         w.appendChild(e);
         e.setAttribute("date","2002-12-24");
         e = d.createElement("name");
         w.appendChild(e);
         e.setAttribute("is_acronym","true");
         e.appendChild(d.createTextNode("DTD"));
         e = d.createElement("definition");
         w.appendChild(e);
         e.appendChild(d.createTextNode("Document Type Definition"));
         printNode(d, "");
      } catch (ParserConfigurationException e) {
         System.out.println(e.toString());
      }
   }
   static void printNode(Node n, String p) {
      NodeList l = n.getChildNodes();
      NamedNodeMap m = n.getAttributes();
      int ml = -1;
      if (m!=null) ml = m.getLength();
      System.out.println(p+n.getNodeName()+": "+n.getNodeType()+", "
         +l.getLength()+", "+ml+", "+n.getNodeValue());
      for (int i=0; i<ml; i++) {
         Node c = m.item(i);
         printNode(c,p+" |-");
      }
      for (int i=0; i<l.getLength(); i++) {
         Node c = l.item(i);
         printNode(c,p+" ");
      }
   }
}

Here is the output with JDK 9 or higher:

herong> java DOMNewDoc.java

#document: 9, 1, -1, null
 dictionary: 1, 1, 0, null
  word: 1, 3, 0, null
   update: 1, 0, 1, null
    |-date: 2, 1, -1, 2002-12-24
    |- #text: 3, 0, -1, 2002-12-24
   name: 1, 1, 1, null
    |-is_acronym: 2, 1, -1, true
    |- #text: 3, 0, -1, true
    #text: 3, 0, -1, DTD
   definition: 1, 1, 0, null
    #text: 3, 0, -1, Document Type Definition

Notice that an attribute is represented twice in the DOM tree.

The same program produces different output with JDK 1.8:

herong> \progra~1\java\jdk1.8.0\bin\java DOMNewDoc

#document: 9, 1, -1, null
 dictionary: 1, 1, 0, null
  word: 1, 3, 0, null
   update: 1, 0, 1, null
    |-date: 2, 0, -1, 2002-12-24
   name: 1, 1, 1, null
    |-is_acronym: 2, 0, -1, true
    #text: 3, 0, -1, DTD
   definition: 1, 1, 0, null
    #text: 3, 0, -1, Document Type Definition