I ran program for POS (Parts of Speech) using Apache Open NLP. which classified words in sentence into verbs,nouns etc. Now I am trying to get polarity of sentence (positive,negative,neutral). I could not do this till now.On searching for help for this using Apache Open NLP I found help for NLP tasks, such as tokenization, sentence segmentation, part-of-speech tagging, named entity extraction, chunking, parsing, and coreference resolution. But nowhere did I get help for polarity.Is this not possible using Apache NLP.Is apache nlp not suited for this.On searching on internet I got LingPipe,alchemy etc. Is it not possible to do this using Apache Open NLP.Should i change approach and switch to some other tool?