Serialization giving probem with HashMap

Question

Hi,
I am creating a new document and could serialize it without fail.
But if I add the created document to the HashMap. and then get the document from hashMap and try to serialize, OutputFormat throws NullPointerException,
Here's the exception message---
java.lang.NullPointerException
        at org.apache.xml.serialize.OutputFormat.whichMethod(Unknown Source)
        at org.apache.xml.serialize.OutputFormat.<init>(Unknown Source)*/
Here's the code I am using--->
HashMap documentsMap = new HashMap();
Document doc= new DocumentImpl();
Element root = doc.createElement("person");     // Create Root Element
Element item = doc.createElement("name");       // Create element
item.appendChild( doc.createTextNode("Jeff") );
root.appendChild( item );       // Attach another Element - 
doc.appendChild( root );        // Add Root to Document
//add to the HashMap....
documentsMap.put("node1",doc );
  try
   Iterator iterator = documentsMap.entrySet().iterator();
   while (iterator.hasNext() )
      Object key = iterator.next();
      doc= (Document)taxonomyNodesMap.get(key);
      OutputFormat format  = new OutputFormat( doc );   //Serialize DOM
      StringWriter  stringOut = new StringWriter();        //Writer will be a  
     XMLSerializer    serial = new XMLSerializer( stringOut, format );
    serial.asDOMSerializer();                            // As a DOM Serializer
    serial.serialize( doc.getDocumentElement());
  }catch......
Any help will be greatly appreciated..
Regards,
Peter

Answer 1

You have to use
Iterator iterator = documentsMap.keySet().iterator();to get an iterator over all KEYS in your Hashmap.
Cheers,
Torsten