The NodeList implementation is not thread safe. When iterating through children 
of a particular node, the NodeList gets changed by another thread doing the 
same action. As a result I get a NullPointerException sometimes and some other 
times I get "wrong document error" when I try to append this clone a child node 
to a document.

The first implementation to access children of a node does not work.

    NodeList childList=root.getChildNodes();
    for (int i=0; i<childList.getLength(); i++)
    {
        // doing something here with "childList.item(i)"
    }
        

The second implementation to access children of a node works.

        Node currChildNode = root.getFirstChild();
        while(currChildNode != null)
        {
        	// Do something here with the "currChildNode"
        	currChildNode = currChildNode.getNextSibling();
        }