I am working on a program written in Java that is currently running and interacting graphically with the users and I want to add a "headless" option so that at runtime I will bind either to the class. that handles the GUI and when I am running headless, I will replace that GUI class with a replacement class where the GUI calls are stubbed out.
The reason I am doing this is that when I tried to run "headless" using crontab. crontab would not run the program emailed me an error message indicating the program required a display.
I have heard I can do runtime binding in Java using an abstract class, but I am asking for help to do that.