Wikipedia:Reference desk/Archives/Computing/2020 July 5

= July 5 =

Java desktop application development
Briefly, what are the steps for turning a Java GUI program that only runs on my IDE into a downloadable desktop application? I know it has something to do with .jar and .exe files, JavaFX, and I’ve read this and this, but it all seems like gibberish to me. So, can someone give me a brief outline of how this works. How do I get started? -- Puzzledvegetable Is it teatime already?  02:29, 5 July 2020 (UTC)
 * If a desktop has a JRE installed, you can distribute your application in form of .jar file together with necessary library (in /lib folder). Ruslik_ Zero 14:21, 5 July 2020 (UTC)
 * Yes, but I was referring to the type of desktop application that someone might download off the internet. Usually, they are in the form of .exe files and don't require having a JRE pre-installed. I think I read somewhere that you can bundle an ad-hoc JRE with the download, but I have no idea how that works. -- Puzzledvegetable Is it teatime already?  15:02, 5 July 2020 (UTC)

Android problem
Hi guys,

I wrote a Android app aiming to read and output Sensor readings. Whereas, the following part keeps throwing me "NullPointerException"

Do you have any idea about solving this? Thank you!

--Deep humility (talk) 08:00, 5 July 2020 (UTC)


 * Something is null. If it happens on that line (as opposed to inside a function called from that line), candidates are the three pointers that are dereferenced on that line: writer, sensorEvent, and sensorEvent.values.  Immediately before that line, print them out to see which one.  Since the function seems to use two of those earlier, I'm guessing writer. 85.76.78.189 (talk) 10:10, 5 July 2020 (UTC)
 * Thank you so much for the clue!! --Deep humility (talk) 09:03, 6 July 2020 (UTC)
 * You could also split the formatting action into four real steps plus one trivial (which formats zeros) and see which will throw the exception. --CiaPan (talk) 12:30, 6 July 2020 (UTC)
 * Ahh, thank you so much. Gonna do it! --Deep humility (talk) 04:42, 7 July 2020 (UTC)


 * I tried what you suggested and the result showed that  is null. Thank you both very much!! --Deep humility (talk) 09:32, 10 July 2020 (UTC)

another GNU emacs isearch mystery
There's a classic old Firesign Theater line, "Then, in the late Devouring period, fish became obnoxious." My problem is that today, in GNU emacs, incremental searches became caseful. I don't know how I did this, and I don't know how to turn it off.

I was probably doing an incremental search, and I probably hit some control key by accident.

According to the manual, I can use M-c to toggle case folding on or off during an incremental search. But that couldn't have been it, because in my emacs now, M-c during an isearch does indeed make that isearch caseless, but the next isearch starts out caseful again. Somehow I've changed the default.

According to that same page, the variable case-fold-search controls the default, but I don't know what key combination I might have hit to turn that variable off, nor have I figured out a way to set it to t again.

I'm probably going to have to exit and restart emacs to fix this (a stinging and ignominious defeat), which would certainly be much more expedient than figuring this out or asking about it here, but my fear is that, whatever I accidentally did, I might do it again, and if I don't notice right away I could make arbitrarily many serious mistakes, searching for strings and concluding they're not there (a technique I use all the time), only to reach a wrong conclusion because of not realizing that isearches had surreptitiously become caseful again.

So, does anyone know how to figure out what key combination might be configured to clear or toggle the value of case-fold-search? —Steve Summit (talk) 13:45, 5 July 2020 (UTC)

[Footnote: Just before posting this, I discovered an entire "customization" subsystem within GNU emacs which I'd never even heard of, and after playing around a bit within it it looks like I've successfully erased a customization and reverted case-fold-search to its former state. But the question remains, what might I have done to accidentally customize it in the first place?


 * I think Emacs would always search case-insensitive unless you type a capital character, in which case it would become case-sensitive. Maybe it's just that you noticed this behaviour at some time (and then never managed to un-notice it)? I find this behaviour quite useful. In general, you can change any variable with, though probably not by accident.  --Stephan Schulz (talk) 23:46, 11 July 2020 (UTC)