Is this exception due to wrong URL but then shouldnt error message be for eg. connection failed etc?
Probably. The DriverManager looks for a driver which can support the URL you give it. If the URL is wrong, its not going to be able to find a driver.
Also "com.ibm.db2j.jdbc.DB2jXADataSource" looks like an XA DataSource, not a driver. Are you sure you are using the right class? The DB2jXADataSource will still need a Driver (which you get from DB2.jar)