Convert set of data into XML document

[Anandh R]

I have a set of data(stored in hashtable) and I need to convert it into XML doc.
Any ideas about how to proceed

[Frank Carver]

Do you want to produce an external XML document (with <tags> etc.) or an in-memory object of class Document?
If it is the first, and the objects in your hashtable are strings (or things representable as strings, such as numbers) then you need something like:

public void export(Map map, PrintWriter out)
{
  out.println("<hashtable>");
  Iterator it = map.keySet().iterator();
  while (it.hasNext())
  {
    Object key = it.next();
    Object value = map.get(key);
  
    out.println("  <element>");
    out.print("    <key>");
    out.print(key.toString());
    out.println("</key>");
    out.print("    <value>");
    out.print(value.toString());
    out.println("</value>");
    out.println("  </element>");
  }
  out.println("<hashtable>");
}

if it is the second case, the you need something like:

public Document export(Map map)
{
  Document doc;
  
  try
  {
    DocumentBuilderFactory factory = DocumentBuilderFactory.newInstance();
    DocumentBuilder builder = factory.newDocumentBuilder();
    doc = builder.newDocument();
  }
  catch(ParserConfigurationException pce)
  {
    pce.printStackTrace();
    return null;
  }
  Element root = doc.createElement("hashtable");
  doc.appendChild(root);
  
  Iterator it = map.keySet().iterator();
  while (it.hasNext())
  {
    Object key = it.next();
    Object value = map.get(key);
  
    Element element = doc.createElement("element");
    root.appendChild(element);
    Element keyElement = doc.createElement("key");
    keyElement.appendChild(doc.createTextNode(key.toString()));
    element.appendChild(keyElement);
    Element valElement = doc.createElement("value");
    valElement.appendChild(doc.createTextNode(value.toString()));
    element.appendChild(valElement);
  }
  
  return ret;
}

I hope this helps.

[Anandh R]

I am creating a hash like this

 void createHashtable( HttpServletRequest request,PrintWriter out )
  {
     RegisterList = new Hashtable();
     RegisterListAddress = new Hashtable();
     RegisterListContact = new Hashtable();
     RegisterList.put("name",request.getParameter("name"));
     RegisterList.put("Address",RegisterListAddress);
     RegisterListAddress.put("ad1",request.getParameter("ad1"));
     RegisterListAddress.put("city",request.getParameter("city"));
     RegisterListAddress.put("contact",RegisterListContact);
     RegisterListContact.put("phone",request.getParameter("phone"));
     RegisterListContact.put("fax",request.getParameter("fax"));

  }

My XML doc is supposed to be
<Register>
<name></name>
<Address>
<ad1></ad1>
<city></city>
<contact>
<phone></phone>
<fax></fax>
</contact>
</Address>
</Register>
</Register>
How do I iterate in a Hashtable and find out if the key has a simple String value or Hashtable. If it has Hashtable I have to iterate further till I find a String
How do I do this

[Frank Carver]

How about this slight modification of my first suggestion:

public void export(Map map, PrintWriter out, String name)
{
  out.println("<" + name + ">");
  Iterator it = map.keySet().iterator();
  while (it.hasNext())
  {
    Object key = it.next();
    Object value = map.get(key);
  
    if (value instanceof Map)
    {
      export(value, out, key)
    }
    else
    {
      out.print("<" + key.toString() + ">");
      out.print(value.toString());
      out.print("</" + key.toString() + ">");
    }
  }
  out.println("</" + name + ">");
}
 
export(RegisterList, out, "Register");

[This message has been edited by Frank Carver (edited December 01, 2000).]

[Frank Carver]

Please note that The Java Ranch has a naming policy, described here and "Anandh R" is not a valid name. Please choose one which meets the requirements.
Thanks.

[Anandh R]

Thanx for the reply but there is some problem
creating hash table

 void createHashtable( HttpServletRequest request,PrintWriter out )
  {
     RegisterList = new Hashtable();
     RegisterListAddress = new Hashtable();
     RegisterListContact = new Hashtable();
     RegisterList.put("name",request.getParameter("name"));
     RegisterList.put("Address",RegisterListAddress);
     RegisterListAddress.put("ad1",request.getParameter("ad1"));
     RegisterListAddress.put("city",request.getParameter("city"));
     RegisterListAddress.put("contact",RegisterListContact);
     RegisterListContact.put("phone",request.getParameter("phone"));
     RegisterListContact.put("fax",request.getParameter("fax"));

  }

displaying hash in XML way

 void displayHash(Hashtable Rlist, PrintWriter out,String name){
           Enumeration ekeys   = Rlist.keys();
           out.println( name );
           out.println("<BR>");
       while(ekeys.hasMoreElements()){
         String key = (String)ekeys.nextElement();
         Object value = Rlist.get(key.toString());
         if (value instanceof Hashtable){
                out.println("<BR>");
                displayHash((Hashtable)value,out,key);
         }else{
               out.println(key);  
               out.println("");
               out.println((String)value);
               out.println("<BR>");
               out.println( key);
         }
             out.println("</" + name + ">");
      }
}

I am to display
Register
Address
city vsssna city

contact
fax sss fax
phone sss phone
ad1 dddd ad1
name aaa name
Register
It is not closing my Address and Contact tags why??
More over why does "ad1" come as a separate element even though it is under Address

[Anandh R]

Thanx I got it..

[Anandh R]

Thanx for the help Frank ..
I need to know what are the imports i have to do if I am tying to save the hash into Document object.
How will I retieve a XML doc from this ???