Informix Nulls and Java Exceptions - Please Help!

We started out allowing nulls all over our database, until we began coding in Java and found that we get a "null pointer exception" in most functions. Is there something we're missing? It seems kind of onerous to always have to put a value in a field, and it seems to be a bigger pain to have to check for null values before calling a function with the raw database field. Thanks for your help.