JAXP DOM reading and writting issues

Question

import org.xml.sax.*;
import org.w3c.dom.*;
import javax.xml.parsers.*;
import javax.xml.transform.*;
import javax.xml.transform.dom.DOMSource;
import javax.xml.transform.stream.StreamResult;
import java.io.*;
public class Test
{   public static void main(String[] args) throws Exception
    {     DocumentBuilderFactory dbf = DocumentBuilderFactory.newInstance();
        dbf.setIgnoringElementContentWhitespace(true);
     DocumentBuilder db = dbf.newDocumentBuilder();
     read(db, "xml_in.xml");
     create(db,"xml_out.xml");
    public static void read(DocumentBuilder db, String fileName)
    {     Document d = null;
     try
     {   d = db.parse(new File(fileName));
     }catch(IOException ex)
     {   ex.printStackTrace();
         return;
     }catch(SAXException ex)
     {   ex.printStackTrace();
         return;
     Node n = d.getDocumentElement();
     System.out.println("Name of the root element: " + n.getNodeName());
     NodeList nl = null;
     nl = d.getElementsByTagName("*");
     System.out.println("Number of element:" + nl.getLength());
     System.out.println();
     nl = d.getElementsByTagName("user");
     System.out.println("Length:" + nl.getLength());
     for(int i=0; i<nl.getLength(); i++)
     {   System.out.println("id: "+nl.item(i).getAttributes().getNamedItem("id").getNodeValue());
         System.out.println("name: "+nl.item(i).getFirstChild().getTextContent());
    public static void create(DocumentBuilder  db, String fileName) throws Exception
     Document d = db.newDocument();
     d.appendChild(d.createComment("This is comment"));
     Element ele_root = d.createElement("root");
     d.appendChild(ele_root);
     Element ele_temp;
     ele_temp = d.createElement("sub");
     ele_temp.setAttribute("id","1");
     ele_temp.appendChild(d.createTextNode("data"));
     ele_root.appendChild(ele_temp);
     ele_temp = d.createElement("sub");
     ele_temp.setAttribute("id","2");
     ele_root.appendChild(ele_temp);
     //adding node
     NodeList nl = d.getElementsByTagName("sub");
     Element ele_parent = (Element)nl.item(0).getParentNode();
     ele_temp = d.createElement("sub");
     ele_temp.setAttribute("id","3");
     ele_parent.appendChild(ele_temp);
     d.normalize();
     Transformer t = TransformerFactory.newInstance().newTransformer();
     //t.setOutputProperty(OutputKeys.METHOD, "test");
     t.transform(new DOMSource(d), new StreamResult(new File(fileName)));
}xml_in.xml
<?xml version = "1.0" ?>
<user-detail>
     <user     id = "1"><name>user1</name><age>10</age></user>
     <user     id = "2">
          <name>user2</name>
          <age>20</age>
     </user>
     <user     id = "3">
          <name>user3</name>
          <age>30</age>
     </user>
</user-detail>The result from read(db, "xml_in.xml"):
>
Name of the root element: user-detail
Number of element:10
Length:3
id: 1
name: user1
id: 2
name:
id: 3
name:
>
both name of id 2 and 3 are missing due to the spacing, how to remove the spacing to avoid this problem?
The result from create(db,"xml_out.xml"):
<?xml version="1.0" encoding="UTF-8" standalone="no"?><!--This is comment--><root><sub id="1">data</sub><sub id="2"/><sub id="3"/></root>how to set it nicely as below?
<?xml version="1.0" encoding="UTF-8" standalone="no"?>
<!--This is comment-->
<root>
     <sub id="1">data</sub>
     <sub id="2"/>
     <sub id="3"/>
</root>thanks~

Answer 1

Removing the whitespace is the wrong approach. Instead you should realize that the creators of that XML can put in whitespace wherever they feel like it, and more importantly, that the whitespace is also part of the document. In particular it forms text nodes which are children of the element in which they are located, just as element nodes are children.
So your strategy of assuming that the "name" element will be the first child of the "user" element is incorrect. When there is whitespace before the "name" element, that whitespace will be the first child. So your strategy should be to get the "name" element which is a child of the "user" element.
And by the way, calling the "normalize" method of the DOM won't do anything to affect that. As usual Ram manages to provide un-useful information.