ClearCL is a Multi-backend Java Object Oriented Facade API for OpenCL.
OpenCL libraries come and go in Java, some are great but then one day the lead developper goes on to greener pastures and you are left with code that needs to be rewritten to take advantage of a new up-to-date library with better support. Maybe a particular library has a bug or does not support the function you need? or it does not give you access to the underlying native pointers, making difficult to process large buffers/images or interoperate with hardware? or maybe it just does not support your exotic OS of choice. To protect your code from complete rewrites ClearCL offers a very clean and complete API to write your code against. Changing backend requires just changing one line of code.