LinuxQuestions.org - [SOLVED] Java and geomapapp

http://www.geomapapp.org

Geomapapp is something I want to run. I installed jdk-8u20 - the only version I could find to download for slackware-current, and I get this sort of error

Code:

bash-4.3$ java ./GeoMapApp.jar

Error: Could not find or load main class ..GeoMapApp.jar

bash-4.3$ javac ./GeoMapApp.jar

Exception in thread "main" java.lang.UnsupportedClassVersionError: com/sun/tools/javac/Main : Unsupported major.minor version 52.0

        at java.lang.ClassLoader.defineClass1(Native Method)

        at java.lang.ClassLoader.defineClass(Unknown Source)

        at java.security.SecureClassLoader.defineClass(Unknown Source)

        at java.net.URLClassLoader.defineClass(Unknown Source)

        at java.net.URLClassLoader.access$100(Unknown Source)

        at java.net.URLClassLoader$1.run(Unknown Source)

        at java.net.URLClassLoader$1.run(Unknown Source)

        at java.security.AccessController.doPrivileged(Native Method)

        at java.net.URLClassLoader.findClass(Unknown Source)

        at java.lang.ClassLoader.loadClass(Unknown Source)

        at sun.misc.Launcher$AppClassLoader.loadClass(Unknown Source)

        at java.lang.ClassLoader.loadClass(Unknown Source)

        at sun.launcher.LauncherHelper.checkAndLoadMain(Unknown Source)

bash-4.3$ javaws ./GeoMapApp.jar

bash-4.3$ Error: A JNI error has occurred, please check your installation and try again

Error: A JNI error has occurred, please check your installation and try again

Is my java too new? Suggestions?