Are there existing JARs available to convert from JSON to XML?
You can create a JSONObject, and then convert it to XML using the XML class in the org.json namespace
Wrapping the json string in the object is as easy as passing it in its constructor
JSONObject o = new JSONObject(jsonString);
Then you can get it in XML format using the XML class, like so:
String xml = org.json.XML.toString(o);