@SuppressWarnings("unchecked")
    private static Class<? extends JsonParser> findJsonParser(String className) {
        Class<?> clazz = null;

        try {
            clazz = Class.forName(className);
        } catch (final Throwable e) {
            LOGGER.log(Level.WARNING, "Unable to access {0}", className);
        }

        if (clazz != null && !JsonParser.class.isAssignableFrom(clazz)) {
            LOGGER.log(Level.WARNING, "{0} does not implement {1}", new Object[] { className, JsonParser.class.getName() });
            clazz = null;
        }

        return (Class<? extends JsonParser>) clazz;
    }
Set the parser to use.

@param clazz
           a class that implements JsonParser
jme3-plugins-json/src/main/java/com/jme3/plugins/json/Json.java