TensorFlow from Google - Data Security
Doesn't TF actually also uses google's models from cloud? I'm pretty sure google uses cloud data to provide better models for TF. 
I'd recommend you to stay away from it. Only by writing your models from scratch you will learn to do useful stuff with it long term. I can also recommend weka for java, it's open source and you can only look at the code of the models there an implement it yourself adjusting for your needs.
Does anyone have any idea whether Google collects data that one supplies to Tensorflow? I mean it is open source, but it falls under their licences.