Weka API: Installing package using package manager - weka

Question

I am trying to use libsvm via Weka API. I have added weka-dev-3.7.6.jar and libsvm.jar to my eclipse build path. The following is the code to load the libsvm library
public static void main(String[] args) {
try {
WekaPackageManager.loadPackages(true);
AbstractClassifier classifier = ( AbstractClassifier ) Class.forName(
"weka.classifiers.functions.LibSVM" ).newInstance();
} catch (InstantiationException e) {
// TODO Auto-generated catch block
System.err.println("error 1");
e.printStackTrace();
} catch (IllegalAccessException e) {
// TODO Auto-generated catch block
System.err.println("error 2");
e.printStackTrace();
} catch (ClassNotFoundException e) {
// TODO Auto-generated catch block
System.err.println("error 3");
e.printStackTrace();
}
}
I got the following error
Refreshing GOE props...
Exception in thread "main" java.lang.UnsupportedClassVersionError: java_cup/runtime/SymbolFactory : Unsupported major.minor version 52.0
at java.lang.ClassLoader.defineClass1(Native Method)
at java.lang.ClassLoader.defineClass(ClassLoader.java:800)
at java.security.SecureClassLoader.defineClass(SecureClassLoader.java:142)
at java.net.URLClassLoader.defineClass(URLClassLoader.java:449)
at java.net.URLClassLoader.access$100(URLClassLoader.java:71)
at java.net.URLClassLoader$1.run(URLClassLoader.java:361)
at java.net.URLClassLoader$1.run(URLClassLoader.java:355)
I added java-cup-11b-runtime.jar on the build path. However, the error persists.

Answer 1

You are trying to run your application with a JVM that does not support Java 8.
Install a Java 8 compatible JRE (or JDK if you need it for development) and use the included JVM to run your application.
Here are the major.minor version numbers mapped to Java versions:
J2SE 8 = 52,
J2SE 7 = 51,
J2SE 6.0 = 50,
J2SE 5.0 = 49,
JDK 1.4 = 48,
JDK 1.3 = 47,
JDK 1.2 = 46,
JDK 1.1 = 45
Read here for a Wikipedia reference.