Trying to enter in textBox random numbers

I am using Selenium with Java.I have log in scenario.Need to create different usernames.I have method which creates different usernames.After Submit btn it will ask for verification code(verification code from DB it will send to that username)I have java class which gets verification code for each created random usernames)After getting this verification code I need to enter that code into "Verification code textfield"So I have my TestNg script with navigating page and entering different username.And I have separate java JDBCGetVerification Code class .How I can join them that my automation script will get the code and after that immediately enter that verification code.Thanks