Hi
You can check the availability of an extension by using CLPlatform.isExtensionAvailable(String extension) and you can use CLProcAddressTable.isFunctionAvailable(String function) to check the availability of a method. You can get the supported version by calling getVersion().
JOCL provides both a low level API and an high level API. The former looks like plain OpenCL whereas the latter is easier to use.