Java run time error?

Whatever program i am writing,even a simple "Hello World" program.The compilation process is fine but while running it is giving same error in every program like "Main Class ---- Not found".....help me out plz

-----------------------------------------------------------------------------------------
Exception in thread "main" java.lang.UnsupportedClassVersionError: Asif : Unsupported major.minor version 51.0
 at java.lang.ClassLoader.defineClass1(Native Method)
 at java.lang.ClassLoader.defineClass(ClassLoader.java:634)
 at java.security.SecureClassLoader.defineClass(SecureClassLoader.java:142)
 at java.net.URLClassLoader.defineClass(URLClassLoader.java:277)
 at java.net.URLClassLoader.access$000(URLClassLoader.java:73)
 at java.net.URLClassLoader$1.run(URLClassLoader.java:212)
 at java.security.AccessController.doPrivileged(Native Method)
 at java.net.URLClassLoader.findClass(URLClassLoader.java:205)
 at java.lang.ClassLoader.loadClass(ClassLoader.java:321)
 at sun.misc.Launcher$AppClassLoader.loadClass(Launcher.java:294)
 at java.lang.ClassLoader.loadClass(ClassLoader.java:266)
Could not find the main class: Asif. Program will exit.
-------------------------------------------------------------------------------------------