I have completely browsed about the issue and came to know that it was due to the version compatible error that occurs within java... Because the number 52 corresponds to version Java 8...
So I upgraded the version from java 7 to java 8... And I also verified it.. The same was mentioned in the hadoop configuration file as well... Now everything is perfect , but still it shows the same error.. I have used maven project in netbeans to build the jar and finally executed it. The following are the version I have in my laptop..

Ubuntu Version : 14.04
Java Version : java-8-oracle
Hadoop Version : 2.6.0
Netbeans : 8.2
Maven : 3.0.3

Pls do anyone help me to sort out the issue. I was struggling with the issue for the past ten days.. I couldn't resolve it....