title: .jar works in Windows but not Linux (stacktrace)
body: <p>This is what I get:</p>
  
  <pre><code>[user@localhost KioskMenu]$ java -jar ./kioskmenu.jar 
  Exception in thread "main" java.lang.ClassFormatError: KioskMenu (unrecognized class file version)
     at java.lang.VMClassLoader.defineClass(libgcj.so.7rh)
     at java.lang.ClassLoader.defineClass(libgcj.so.7rh)
     at java.security.SecureClassLoader.defineClass(libgcj.so.7rh)
     at java.net.URLClassLoader.findClass(libgcj.so.7rh)
     at gnu.gcj.runtime.SystemClassLoader.findClass(libgcj.so.7rh)
     at java.lang.ClassLoader.loadClass(libgcj.so.7rh)
     at java.lang.ClassLoader.loadClass(libgcj.so.7rh)
     at gnu.java.lang.MainThread.run(libgcj.so.7rh)
  [user@localhost KioskMenu]$ 
  </code></pre>
  
  <p>The only thing I noticed was that my RHEL is using a "free" version of Java. But this shouldn't matter should it?</p>