java - Open NLP Name Finder Output -

i starting learn opennlp api jave. found examples in website

http://www.programcreek.com/2012/05/opennlp-tutorial/

i have tried name finder api found strange. if replace input as

string []sentence = new string[]{             "john",             "is",             "good"             }; 

the code still working, if change as

string []sentence = new string[]{             "john",             "is",             "fine"             }; 

there no output.

i cannot understand causes problem. form model use? (en-ner-person.bin) , know how can build own model?

thanks!

assuming not throwing exception , can't find name "john," it's not working because model cannot find john when sentence "john fine" because opennlp machine learning approach , finds named entities based on model. en-person.bin model apparently not have sufficient samples of sentences similar enough "john fine" return probability high enough give response.