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Fail to initialize resources in android app - then NullPointerException

So, I have this android application and even some users. As I have a crash report system, I can see when someone's app crashes and the cause.
It appears that, though rarely, the app crashes randomly with NullPointerException when it tries to change some attributes(rotation, text, etc..). I make sure everything is set first thing in the onViewCreated method(using Fragments) like this:
private TextView orientationView;
orientationView = this.getActivity().findViewById(R.id.orientationView);
Using this ^^ example, I then try to hide/show this view and get an exception as it appears to be null sometimes, which is what I struggle to figure out why.
orientationView.setVisibility(View.VISIBLE); // app crashes when orientationView is null
Being a newbie in android development, I am not sure if it is a good practice, but in some of the fragments, I set all the previously initialized resources to null in the onDestroyView method, but the one that crashes the most doesn't have this method implemented, which make me to believe that somehow the resources are just not found/initialized in some rare occasions and I fail to change them later with an exception.
Could someone help me figure this out :) (more description could be provided, if needed)

Android FireBase OnDataChange code not being permanant

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I get the followingg Toast outputs
CODE IS RUNNING
and
s
So my code is running but my_shop is not being changed?

Your code is working fine, I think you are a bit confused as to how the code above actually works. the onDataChanged method is triggered/called asynchronously ONLY when the data in the database/server changes, hence the toast-'CODE IS RUNNING' is displayed correctly.
But you are checking the my_shop.getShop_name() outside the onDataChanged method, hence by the time the program counter reaches the second toast, the onDataChanged method hasn't been called yet. The shop_name is still the one that you assigned in line 2 which is what is displayed on the Toast! (which is why you think the code isn't running properly even if it is working fine!)
I would suggest you read more about event listeners in general to get a better idea abouut this behaviour! you can read more about the API in the firebase documentation: https://firebase.google.com/docs/database/android/read-and-write

'this#ActivityName' is not captured error Android/Kotlin

I'm repairing my friend's code and got confused.
My friend wants to fetch entered text (in EditText). Seems easy, right? Well, it is but instead of user input, he gets this warning/error:
To be honest I'm not sure how to fix it. He is coding in Kotlin (Android 10).
Activity that contains EditText:
And XML:
This is how it looks when debugging:
The app started working just fine after running "File -> invalidate Cashes/Restart" option, I just don't understand where this warning came from and how to fix it because the error remained unchanged (even though the app works). Do you have an idea how to solve it?
All the best!

fyi lambda expression like setOnClickListener from kotlin is not debuggable, see here.
if you want to debug variables inside setOnClickListener you should use the normal one e.g. setOnClickListener(object: View.OnClickListener {..})

sometimes there will be problem in auto generated binding files, if so it will be solved after invalidate cache and restart ide. sometimes the warning/error show but the project and complied without errors. so no need to worry about that. for next time post the code as code not screen shots.

I understand that the question is regarding evaluating expression, but there is a way you can read variables from your debugger console, even if you're inside an anonymous callback. I found it helpful sometimes. Here are the steps:
First enter debugger mode inside of your anonymous callback,
In your debugger console, look at the right side for "Frames"
Within Frames under , you'll see stack of function execution first top one on the list is the latest:
Click on row(s) below the latest function, until you find an instance of your activity AddInformationActivity. You will see the activity instance on the right side window under Variables. Don't go as far as selecting functions browned out, because those are from internal libraries.
When you see you AddInformationActivity instance, you can expand it and see its variables.
Hope that helps!

It's not a beautiful way, but if you create a method like this:
private fun debug() {
println()
}
and add a breakpoint on the println() it'll capture the activity.
(Don't use TODO as it'll crash the app with a NotImplementedError once called.)
I have this method now in my code all the time to call it whenever I need it.
I know, that question is old, but I just stumbled over it and needed a way.

Is there a way to trace who invoked onNext() on a Subject, in RxJava(2)?

I am developing an Android app (It doesn't matter though) using RxJava2, and in some singleton there are some PublishProcessors.
And there are a lot of .onNext() calls on these PublishProcessors all over the project.
Now in order to debug, I need to know, on every .onNext() called, which line in my project invoked this .onNext().
Is there a way in RxJava(2) that I can achieve this?

I think you can use Frames tab in Debug menu.
For example, in this case, MainActivity line 18 trigger onNext

Ah, thanks to #PhanVanLinh, I found a solution that worked for me.
(Actually it has pretty much nothing to do with RxJava...)
You just need to print the stacktrace using Thread.currentThread.stackTrace and print it to your own string inside doOnNext(), but remember to do it before .observeOn() so that the thread won't switch, it must stay at the original thread that called .onNext(), otherwise you won't get meaningful information.
Then you will know which line that called .onNext().

R.id. values get overwritten

In my Android app I'm creating new WebViews from Java code; however after I create these WebViews my previously working id's get overwritten.
Example snippet:
for (int i=0;i<mywebviewarray.length;i++){
mywebviewarray[i]=new WebView();
}
((Button)findViewById(R.id.mybutton).settext("ok");
If I run this code, I get an exception on the last line:
java.lang.ClassCastException: android.webkit.WebView
It seems to me as if the tables backing the findViewById get overwritten. I tried calling setId in the loop. but it does not help.
How can I resolve this problem?

What is in mywebviewarray. It seems to me like you have something in there that isnt a WebView and you are trying to instantiate it as a WebView.

I ended up not solving this problem, and instead of using a dynamic array of WebViews, I ended up using fixed 3 WebViews. I'm changing their content like a 3-length window over an array of URLs, thus simulating the original concept. (Albeit in a slower way)