Hi,
I use this class to call methods of other classes:
public class FunctionHandler {
    public static String execRoutine(String longName, List<String> args)
            throws Exception {
        String ret;

        int dot = longName.lastIndexOf('.');
        String className = longName.substring(0, dot);
        String funcName = longName.substring(dot + 1);

        printf("class name: " + className);
        printf("func name: " + funcName);
        Class c = Class.forName(className);

        Method routine = c.getMethod(funcName, List.class);
        printf("method: " +
routine.getGenericParameterTypes()[0].toString());
        ret = (String) routine.invoke(args);
        return ret;
    }
}

And this is the class whose method is going to be called:
public class Math {
    public static String C(List<String> args) {
        int n, r;

        n = Integer.parseInt(args.get(0));
        r = Integer.parseInt(args.get(1));

        Combination c = new Combination(n, r);
        return String.valueOf(c.getTotal());
    }
}

But I got the following exception:
java.lang.IllegalArgumentException: wrong number of arguments
    at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
    at
sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:39)
    at
sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:25)
    at java.lang.reflect.Method.invoke(Method.java:585)
    at
com.gsta.enrus.services.el.FunctionHandler.execRoutine(FunctionHandler.java:23)

Why?