How to generate bigram/trigram/unigram probability?

Hi, all:

I want to generate word unigram/bigram/trigram probability. Is there an example to show how to do it? like "I am newbie......" in a file. The generated list may be:

bigram:
1. I am 0.23
2. I want 0.20
3. I like 0.19
...

I read a very short piece by Manning, but it does not show to compute.

Please help.

Thank you in advance.

How does this problem relate to java programming?

It is closely related to Java for search engine building, abstract extraction, data estimates and prediction, speech recognition...

I'm with Norm as this seems to me to be an algorithm question, not a Java question per se.

Dear Norm and Fubarable:

Thanks. I know little about Lucene. But, Is there sth in Lucene that generates bigram/trigram for indexing and search. Does it relate to Java programming?

Thanks.