## Tuesday, June 11, 2019

### A Swing Platform for Computational Experiments

Most of my research involves coding algorithms and running computational experiments with them. It also involves lots of trial-and-error, both with the algorithms themselves and with assorted parameters that govern their functioning. Back in the Dark Ages, I did all this with programs that ran at a command prompt (or, in Linux terms, in a terminal) and wrote any output to the terminal. Eventually I got hip and started writing simple GUI applications for those experiments. A GUI application lets me load different problem without having to stop and restart the program, lets me change parameter settings visually (without having to screw around with lots of command line options ... is the switch for using antisymmetry constraints -A or -a?), and save output to text files when it's helpful.

Since I code (mostly) in Java, the natural way to do this is with a Swing application. (When I use R, I typically use an R notebook.) Since there are certain features I always want, I found myself copying code from old projects and then cutting out the project-specific stuff and adding new stuff, which is a bit inefficient. So I finally got around to creating a minimal template version of the application, which I'm calling "XFrame" (short for "Experimental JFrame" or "JFrame for Experiments" or something).

I just uploaded it to Bitbucket, where it is open-source under a very nonrestrictive Creative Commons license. Feel free to download it if you want to try it. There's an issue tracker where you can report any bugs or sorely missing features (but keep in mind I'm taking a fairly minimalist approach here).

Using it is pretty simple. The main package (xframe) contains two classes and an interface. You can just plop them into your application somewhere. One class (CustomOutputStream) you will probably not want to change. The actual GUI is the XFrame class. You will want to add menu items (the only one it comes with is File > Exit) and other logic. Feel free to change the class name as well if you wish. Finally, your program needs to implement the interface defined in XFrameController so that XFrame knows how to talk to the program.

The layout contains a window title at the top and a status message area at the bottom, both of which can be fetched and changed by code. The central area is a scrollable text area where the program can write output. It has buttons to save the content and to clear it, and the program will not exit with unsaved text unless you explicitly bless the operation.

There is a function that lets the program open nonmodal, scrollable dialog (which can be left open while the main window is in use, and whose content can be saved to a file). Another function allows the program to pop up modal dialogs (typically warnings or error messages). Yet another function provides a place where you can insert logic to tell the GUI when to enable/disable menu choices (and maybe other things). Finally, there is a built-in extension of SwingWorker that lets you launch a computational operation in a separate thread (where it will not slow down or freeze the GUI).

I included a small "Hello world!" application to show it works. I'll end with a couple of screen shots, one of the main window and the other of the nonmodal dialog (both from the demo). If it looks like something you might want to use, please head over to Bitbucket and grab the source.

 Main window
 Nonmodal dialog