java.lang.UnsupportedClassVersionError Unsupported major.minor version 51.0 [duplicate]
These guys gave you the reason why is failing but not how to solve it. This problem may appear even if you have a jdk which matches JVM which you are trying it into.
Project -> Properties -> Java Compiler
Enable project specific settings.
Then select Compiler Compliance Level to 1.6 or 1.5, build and test your app.
Now, it should be fine.
java.lang.UnsupportedClassVersionError happens because of a higher JDK during compile time and lower JDK during runtime.
Here's the list of versions:
Java SE 9 = 53,Java SE 8 = 52,Java SE 7 = 51,Java SE 6.0 = 50,Java SE 5.0 = 49,JDK 1.4 = 48,JDK 1.3 = 47,JDK 1.2 = 46,JDK 1.1 = 45
Version 51 is Java 7, you probably use the wrong JDK. Check JAVA_HOME.