HP Prime Android Application (2016.12.08 1.3.1.11226) is clearing user apps/programs

[Tim Wessman]

So basically what is happening here is that there is the idea of "persistent bits" in the Core calculator code. This is from the calculator hardware, where it sets bits in the processor on boot at certain stages. If certain bits repeat, it will attempt to bypass loading files, some other troubleshooting things, or in a final case "erase" the disk. Basically, it is a fail safe to prevent the user from getting stuck in a boot loop.

This was previously not implemented in the android app and occasionally users would report having to "uninstall and reinstall" to fix things. However, it seems that something is not happening as expected. Currently, it is using a small file on the disk to keep this "persistant bit" information. I suspect that the file isn't being written out to flash because of an OS caching mechanism. When you force close the application, the file is not being written out before hand.

A "shift-off" will "save" the files currently in the calculator which explains why you see that. If you changed your "TOff" value to something smaller, this would also happen when that is called as well. In addition, it is supposed to call this when you press home in the task switching calls. However, opening the "force kill" screen might not be saving things...

Android/iOS are new to the HP Calculator group in many ways, and certain things like this are bound to pop up unfortunately as we encounter some of platform specific quirks.

[switching over to technical discussion here - you may want to stop if not interesting to you... ]

So a more technical question for anyone with android development (w/NDK) experience...

What would be the appropriate mechanism for storing some information that must persist permanently between application runs *used within the NDK*? On first glance, I wanted to use a SharedPreferences object. However, that seemed overkill and has no simple way to access from the NDK side of things, so I thought a simple file read/write would be the way to go. Suggestions?