public static <T> Instantiator<T> newInstantiator(Class<T> clazz)
    {
        final Constructor<T> constructor = getConstructor(clazz);
        if (constructor == null)
        {
            // non-sun jre
            if (newInstanceFromObjectInputStream == null)
                throw new RuntimeException("Could not resolve constructor for "
                        + clazz);

            return new Android2Instantiator<T>(clazz);
        }

        return new DefaultInstantiator<T>(constructor);
    }
Returns an instatiator for the specified {@code clazz}.
protostuff-runtime/src/main/java/io/protostuff/runtime/RuntimeEnv.java