Fatal error while parsing XML using XPath in Java

Question

I want to parse a XML file. It throws the Exception while creating object:

Document doc = builder.parse("Response.xml");

Exception:

[Fatal Error] Response.xml:63:67: The prefix "UDF" for element "UDF:RTSIDUDF.LIST" is not bound.
Exception in thread "main" org.xml.sax.SAXParseException: The prefix "UDF" for element "UDF:RTSIDUDF.LIST" is not bound.
    at com.sun.org.apache.xerces.internal.parsers.DOMParser.parse(DOMParser.java:249)
    at com.sun.org.apache.xerces.internal.jaxp.DocumentBuilderImpl.parse(DocumentBuilderImpl.java:284)
    at javax.xml.parsers.DocumentBuilder.parse(DocumentBuilder.java:180)
    at tallyreqandresponse.Ledger.main(Ledger.java:38)
Java Result: 1

Sample xml Code:

 <A>
 <LANGUAGENAME.LIST>
   <NAME.LIST TYPE="String">
       <NAME>ABC India (P) Ltd.,</NAME>
   </NAME.LIST>
   <LANGUAGEID TYPE="Number"> 1033</LANGUAGEID>
   <UDF:RTSIDUDF.LIST DESC="`RTSIDUDF`" ISLIST="YES" TYPE="Number">
       <UDF:RTSIDUDF DESC="`RTSIDUDF`"> 1387</UDF:RTSIDUDF>
   </UDF:RTSIDUDF.LIST>
   </LANGUAGENAME.LIST>
 </A>

Kindly help me out of it.

Edit Note: Added LANGUAGENAME.LIST Opening tag

Answer 1

Your input markup is not namespace well-formed XML so it is rejected by the XML parser. You need to fix the input with eg

<A>
 <NAME.LIST TYPE="String">
       <NAME>ABC India (P) Ltd.,</NAME>
 </NAME.LIST>
 <LANGUAGEID TYPE="Number"> 1033</LANGUAGEID>
       <UDF:RTSIDUDF.LIST xmlns:UDF="http://example.com/" DESC="`RTSIDUDF`" ISLIST="YES" TYPE="Number">
                      <UDF:RTSIDUDF DESC="`RTSIDUDF`"> 1387</UDF:RTSIDUDF>
      </UDF:RTSIDUDF.LIST>
  </LANGUAGENAME.LIST>
</A>

Answer 2

Beside the missing namespace definition it also seems that there is a mismatched tag:

</LANGUAGENAME.LIST> 

has no corresponding opening tag.

If you Google xml namespaces you get plenty of good links - have a look here for example.