The program I have built basically takes in two arrays, numbers and operators, and displays the equation.  Right now, I need to hard-code the numbers and operators arrays in void setup{}.  I would like to have a popup window before void setup{} runs that asks the user to type in an equation, and then I can parse this text and use it to fill up the numbers and operators arrays upon setup.  

Is there some way to write a new Processing sketch for this prompt and parsing, and have it feed outputs into my equation sketch?  Or should I empty out the void setup{} section, move it to void draw{} with a "setup" flag?  Then I can use the void setup{} section to run the prompt?

Thanks for your help.  I apologize if this is a silly/overdiscussed topic.