need help in merging GUI and logic main program

hi..i got a problem in using netbeans. here i have a main program namely MainApp which consists of array list and all the logic program. Instead of using JOptionPane asking for user input, i want to use GUI.i already design a gui interface but, i have no idea how to call the MainApp main program to be insert into GUI class so that they could run together..

please..can anyone here help me..?i am really stuck.

Are you trying to show another window from MainApp?

Your question is very general and vague, has no simple answer. I think that you'll want to provide the important details. Please read the link below in my signature on how to write smart questions as it will tell you many of the bits of information that we need in order to be able to help you.

For instance, how is your MainApp structured? Does it consist of several classes that interact in decent OOP fashion? If so, then your chances of using this code successfully in a separate GUI class is good. Or does the MainApp class mainly consist of a single main method perhaps with a few other static methods, in which case, forget creating a GUI until you first OOP-ify your code.