NoSuchMethodError: JobConf.getCredentials()
Fortunately I found Answer of my question myself. I have to include a jar file in build path hadoop-0.20.2+737-core.jar instead of hadoop-0.20.2-core.jar. It looks like it is the modified version of the same file containing JobConf Class containing getCredentials() method.
Problem is solved but I am still confused about those two versions? Is any body know whats the actual difference?