I am following the below tutorial to retrieve XMLType data from a stored procedure
http://docs.oracle.com/cd/B19306_01/appdev.102/b14259/xdb11jav.htm#g1039140 E
Issue fixed by adding the required jars
Needed the following three jars in the classpath, [I had these jars still, I was getting error due to wrong versions of the jar]
ojdbc6.jar, xdb6.jar, xmlparserv2-11.1.1.jar
Even if you have these jars, you might get error like I was getting when I was including a wrong version of xmlparserv2.jar.
So Important thing to take care is the version and compatibility of these jars.
The ones that worked for me [My Oracle DB version : 11.2.0.4.0]
ojdbc6.jar; xdb6.jar:
http://www.oracle.com/technetwork/database/enterprise-edition/jdbc-112010-090769.html
xmlparserv2-11.1.1.jar available here: ( SQL Developer ) (in sqldeveloper\modules\oracle.xdk_12.1.2)
[removed third party reference link as advised by @Lukas Eder, Thanks for that]