Choose nlp api (java)

I am (very) new to the field of NLP, I tried to look for an API (in Java) that can tell me if two pieces of text have the same meaning (or if one is derived by the other) for example:

"billy said tom was a nice kid"

is the same as

"tom is a nice kid according to billy"

I checked GATE and openNlp and it seems like GATE only offers API for annotations and openNlp doesnt support it as well.

Omri, no existing piece of software, in Java or another programming language, can tell you this. Text understanding is the holy grail of natural language processing.

I suggest you start by doing smaller tasks, and gradually approach this vast task. Please see this question and the answers.com page on nlp for some pointers. Textual Entailment, an active research area, may be close to what you are asking about.

You can try the Retina API from Cortical.io: it measures the semantic similarity of any two texts using several distance measures (Cosine Similarity, Jacquard Distance, Euclidian Distance...). You can even get a visual representation of the semantic overlap.