genetic algorithm program using java

Well, this is not a simple question... (Since the field you dig into is still very much research).

I would recommend:

1. read current articles about automatic text summarization and application of genetic algorithms

For this you can search on scholar.google.com or e.g. conference proceedings of AI conferences such as ECAI or IJCAI.

2. Understand the Data:

I.e. you have a sentence where you model some of the Information into a sequence of values, which then "kind of" form your "gene-sequence". The problem here is to find significant information from which can be concluded, that a specific word needs to be in the summary, e.g. the word's frequency in the text (but careful here: stopwords like "no", "yes", etc. should be filtered here) otherwise you will need so much data to train you model, that it will simply be unfeasible.

3. Check on Standard preprocessing methods in Computer Linguistics, such as stemming, stop-word filtering, Taggers for phrase types etc. These will all reduce your search space and simplify your search for the "gene"-sequence ;)

4. To me it seems to be an extremely ambitious project (but I'm out of the field for a few years now...)

Hope this helps a bit,
Cheers, Arndt