Attempt to invoke virtual method android.view.ViewGroup:LayoutParams android.view.View.getLayoutParams() on a null object reference

[javieranton-zz]

Here is the full stack trace, originating from Dialog blockScreen = new InfiniteProgress().showInfiniteBlocking();

_07-17 02%3A04%3A46.982 7653 7681 W System.err%3A java.lang.NullPointerException%3A Attempt to invoke virtual method android.view.ViewGroup%24LayoutParams android.view.View.getLayoutParams() on a null object reference 07-17 02%3A04%3A47.058 7653 7681 W System.err%3A at com.codename1.impl.android.a.a(AndroidAsyncView.java%3A409) 07-17 02%3A04%3A47.058 7653 7681 W System.err%3A at com.codename1.impl.android.f.a(AndroidImplementation.java%3A1650) 07-17 02%3A04%3A47.058 7653 7681 W System.err%3A at com.codename1.impl.a.t(CodenameOneImplementation.java%3A644) 07-17 02%3A04%3A47.058 7653 7681 W System.err%3A at com.codename1.w.s.m(Display.java%3A1249) 07-17 02%3A04%3A47.058 7653 7681 W System.err%3A at com.codename1.w.s.k(Display.java%3A1015) 07-17 02%3A04%3A47.058 7653 7681 W System.err%3A at com.codename1.w.x.a(Form.java%3A2356) 07-17 02%3A04%3A47.058 7653 7681 W System.err%3A at com.codename1.w.r.a(Dialog.java%3A1138) 07-17 02%3A04%3A47.058 7653 7681 W System.err%3A at com.codename1.w.r.a(Dialog.java%3A582) 07-17 02%3A04%3A47.058 7653 7681 W System.err%3A at com.codename1.w.r.a(Dialog.java%3A1439) 07-17 02%3A04%3A47.058 7653 7681 W System.err%3A at com.codename1.w.r.b(Dialog.java%3A1355) 07-17 02%3A04%3A47.058 7653 7681 W System.err%3A at com.codename1.g.d.d(InfiniteProgress.java%3A182)

This happens very rarely but consistently

[shai-almog]

While this might be a problem I would strongly recommend you don't do that. Showing a dialog on top of a dialog can lead to a problem where disposing the dialog leads back to the previous dialog and this might actually cause a cycle of dialogs disposing and going "back" to each other.

[javieranton-zz]

No worries I will work around it

Thx

[javieranton-zz]

Could you be a bit more specific, I'd really appreciate it if you could

Does this apply to all types of dialogs? I mean, for example, is it ok to show a Dialog on top of an AnimatedDialog, but not ok to show an infinite blocking over an AnimatedDialog?

Or is there some combination that's safe?

[shai-almog]

Yes, anything that derives from from dialog will be problematic.

The crux of the issue is the concept of dispose() it works by going back to the parent Form. The thing is that Dialog derives from Form which is pretty elegant but also problematic. So when you dispose a dialog and the previous form is a dialog it will show that dialog. The problem is that now the "previous" dialog thinks its previous form was the other dialog and that can create an infinite loop of one dialog showing the previous one...

Generally we also try to avoid infinite progress dialog in newer UIs. I didn't like it when we added it but it was a common UI paradigm at the time. E.g. if you look in the new settings UI what we do is just add the InfiniteProgress into the user interface to indicate we're working. The rest of the UI is still usable during this time which is pretty cool. If a specific button should be disabled we just use setEnabled(false) instead. This makes the app feel more responsive.

E.g. check out this post: https://www.codenameone.com/blog/data-loading-placeholders.html and this older post https://www.codenameone.com/blog/dont-block-the-ui.html

[javieranton-zz]

That's really informative thanks a lot. I will definitely overhaul lots of code now that I know this My initial question still haunts me because AnimatedDialod derives from Container, so I am still unsure how it fits into this

[javieranton-zz]

To be honest I haven't seen this error in a while and after what you've said it sounds like it shouldn't happen. I wonder if it was related to a different network error in my app that I recently fixed. I will close this for now to tidy up issues a bit. If it comes back I will reopen

[javieranton-zz]

Got some more news... the error happened again a couple of times

It happened when showing a standard Dialog with a Form with a Browser in the background (no other Dialog or AnimateDialog opened at the time)

The error got thrown when invoking showPacked(BorderLayout.CENTER, true);

Edit: if I try it on my device I don't see the error so it must be a race condition/device specific etc

[javieranton-zz]

Error now happening with somewhat different stack trace. What the errors have in common is that a BrowserComponent is in the center of the Form

_08-13 10%3A17%3A33.442 4006 4044 W System.err%3A java.lang.NullPointerException%3A Attempt to invoke virtual method android.view.ViewGroup%24LayoutParams android.view.View.getLayoutParams() on a null object reference 08-13 10%3A17%3A33.447 4006 4044 W System.err%3A at com.codename1.impl.android.a.a(AndroidAsyncView.java%3A335) 08-13 10%3A17%3A33.447 4006 4044 W System.err%3A at com.codename1.impl.android.f.a(AndroidImplementation.java%3A3929) 08-13 10%3A17%3A33.448 4006 4044 W System.err%3A at com.codename1.w.s.l(Display.java%3A1155) 08-13 10%3A17%3A33.448 4006 4044 W System.err%3A at com.codename1.w.aq.run(RunnableWrapper.java%3A120) 08-13 10%3A17%3A33.448 4006 4044 W System.err%3A at com.codename1.impl.b%241.run(CodenameOneThread.java%3A60) 08-13 10%3A17%3A33.448 4006 4044 W System.err%3A at java.lang.Thread.run(Thread.java%3A784)_