Not sure how your question relates to Broadleaf Commerce. For general help with programming concepts like this, you might just try your luck with Google or StackOverflow.
If you have a question specific to Broadleaf please provide more context.
This forum is in readonly mode and serves as an archive of old information. All posting, registration and commenting abilities have been turned off. To get help, the Broadleaf team reguarly monitors the broadleaf-commerce tag on Stack Overflow so please ask your questions there.