Get parameter Type from dunamic method using reflection

I've got this bit of code to get a setter method from a dynamic class. But the parameters can be a java.lang.String or java.lang.Long. How can I dynamically get the parameter type?

public Method getDynMethod(Class aClass, String methodName) {
    Method m = null;
    Class[] paramTypes = new Class[1];
    paramTypes[0] = String.class;
    try {
        m = aClass.getMethod(methodName, paramTypes);
    } catch (NoSuchMethodException nsme) {
        nsme.printStackTrace();
    }
    return m;
}

This is the code that calls it

Class c = getDynClass(a.getAssetType().getDBTableName());
        for (Long l : map.keySet()) {
            AssetProperties ap = new AssetProperties();
            ap.setAssetTypeProperties(em.find(AssetTypeProperty.class, l));
            ap.setAssets(a);
            ap.setValue(map.get(l));
            a.getAssetProperties().add(ap);
            String methodName = "set" + ap.getAssetTypeProperties().getDBColumn();
            Method m = getDynMethod(c, methodName);
            try {
                String result = (String) m.invoke(c.newInstance(), ap.getValue());
                System.out.println(result);
            } catch (IllegalAccessException iae) {
                iae.printStackTrace();
            } catch (InvocationTargetException ite) {
                ite.printStackTrace();
            } catch (InstantiationException ie) {
                ie.printStackTrace();
            }

        }

I could pass another parameter to the method but I still would not know what the parameter type would be