In the past when I wrote an Android app using Processing-Android open-source code SDK, I could not combine Android GUI elements with my Processing code. It was not possible to mix the Android GUI features with a Processing sketch in a display screen. I had to rely on special purpose GUI libraries written by volunteers to add more elaborate graphical elements to an app.
During the past year the open-source Android Processing Language development team volunteers modified the internal substructure code of Processing-Android to use Android Fragments instead of Activity classes, thereby allowing Android GUI elements to be combined with Processing GUI sketches within a single screen display in an app.
Searching the Internet I could not find any examples of code that combined the GUIs. I modified (forked) the Processing Android Demo code on Github.com to use as a base for some new examples of Processing Android code I wrote that combines Processing sketches with Android GUI elements. Use this link to see the Android Studio project code:
https://github.com/ajavamind/ProcessingAndroidDemo
For Processing coders It's a little more complicated because you will have to use Android Studio SDK instead of the Processing SDK to combine the code development libraries.
