navigation-compose 2.4.0-alpha05 empty screen on bottom nav tab reselection [194925622]

Fixed

Bug

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Description

yu...@gmail.com

created issue #1

Jul 28, 2021 10:26PM

Component used: Navigation Compose

Version used: androidx.navigation:navigation-compose:2.4.0-alpha05

Devices/Android versions reproduced on: Android 12 beta

Problem: When re-selecting the same tab (i.e clicking already selected tab), the screen becomes empty. It doesn't happen when current destination is the root graph's startDestination.

I first noticed this on my app, then confirmed it by trying it on github.com/chrisbanes/tivi and upgrading nav compose to 2.4.0-alpha05.

screen-20210728-171440.mp4

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il...@google.com <il...@google.com> #2Jul 28, 2021 10:56PM

Oh I forgot to mention that I thought it might be connected to this issue: https://issuetracker.google.com/issues/243778589. But after trying 2.5.2 I can say that the issue persists.

yu...@gmail.com <yu...@gmail.com> #3Jul 28, 2021 11:59PM

Please provide a minimal sample project along with the minimal steps to recreate the issue in the project.

NavigationComposeBug.zip

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navigation-alpha04-normal.mp4

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navigation-alpha05-buggy.mp4

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il...@google.com <il...@google.com> Jul 29, 2021 12:09AM

Assigned to jb...@google.com.

m....@futuremind.com <m....@futuremind.com> #4Jul 29, 2021 09:51AM

Sorry for the delay. I got a working example here: https://github.com/Del-S/issues. The project is set up to crash when navigating to ThirdFragment (nested nav graph) with poping the graph.

I poked into it a little bit and it seems to be connected to SafeArgs gradle plugin. When safe args is used to navigate to ThirdFragment (with nested graph poped) it will try to recreate te parent but there were no arguments passed so it crashes.

Steps to reproduce:

Navigate from Second Fragment to Child nav graph (with non-nullable parameters).
Navigate to Third fragment using SafeArgs and the app crashes.

Crash log:

Process: cz.dels.issues, PID: 1743
java.lang.NullPointerException: null cannot be cast to non-null type kotlin.Long
at androidx.navigation.NavType$Companion$LongType$1.get(NavType.kt:352)
at androidx.navigation.NavType$Companion$LongType$1.get(NavType.kt:342)
at androidx.navigation.NavArgument.verify(NavArgument.kt:76)
at androidx.navigation.NavDestination.addInDefaultArgs(NavDestination.kt:502)
at androidx.navigation.NavController.addEntryToBackStack(NavController.kt:1865)
at androidx.navigation.NavController.addEntryToBackStack$default(NavController.kt:1813)
at androidx.navigation.NavController$navigate$4.invoke(NavController.kt:1721)
at androidx.navigation.NavController$navigate$4.invoke(NavController.kt:1719)
at androidx.navigation.NavController$NavControllerNavigatorState.push(NavController.kt:287)
at androidx.navigation.fragment.FragmentNavigator.navigate(FragmentNavigator.kt:246)
at androidx.navigation.fragment.FragmentNavigator.navigate(FragmentNavigator.kt:162)
at androidx.navigation.NavController.navigateInternal(NavController.kt:260)
at androidx.navigation.NavController.navigate(NavController.kt:1719)
at androidx.navigation.NavController.navigate(NavController.kt:1545)
at androidx.navigation.NavController.navigate(NavController.kt:1472)
at androidx.navigation.NavController.navigate(NavController.kt:1930)
at cz.dels.issues.SecondFragment.onViewCreated$lambda-0(SecondFragment.kt:38)
at cz.dels.issues.SecondFragment.$r8$lambda$XDYnOS_cYrafiNQ5rcCu1WCn0IE(Unknown Source:0)
at cz.dels.issues.SecondFragment$$ExternalSyntheticLambda0.onClick(Unknown Source:2)

Note: If in step 2 SaveArgs is not used then navigation works correctly. More information is here: https://github.com/Del-S/issues/blob/master/app/src/main/java/cz/dels/issues/SecondFragment.kt#L37.

co...@protonmail.com <co...@protonmail.com> #5Aug 5, 2021 05:10AM

Ups a typo: Navigate from ~~Second~~ First Fragment to Child nav graph (with non-nullable parameters).

Note: sorry for the spam but I am not able to edit my own comment.

ap...@google.com <ap...@google.com> #6Aug 12, 2021 12:16AM

This has been fixed and will be available in navigation 2.6.0-alpha08

jb...@google.com <jb...@google.com> #7Aug 12, 2021 03:02AM

Marked as fixed.

Project: platform/frameworks/support
Branch: androidx-main

commit 6b358154b794a0456b089ac8e548bfb830dd6c22
Author: Clara Fok <clarafok@google.com>
Date: Tue Mar 14 17:56:12 2023

Fix missing non-nullable arg when rebuilding hierarchy

When navigating with NavDirections, args is populated with an empty bundle. This causes issue when we rebuild parent hierarchy while adding a new entry to NavBackStack. If the Entry being rebuilt contains a non-nullalbe arg, i.e. Long, this empty bundle will cause an exception.

Test: ./gradlew navigation:navigation-runtime:cC
Bug: 249988437
Change-Id: I5c8ce739ad9a3428c8a8de13eae391bfff0db5df

M navigation/navigation-runtime/src/androidTest/java/androidx/navigation/NavControllerTest.kt
M navigation/navigation-runtime/src/main/java/androidx/navigation/NavController.kt

https://android-review.googlesource.com/2488855

yu...@gmail.com <yu...@gmail.com> #8Aug 13, 2021 03:52AM

The following release(s) address this bug.It is possible this bug has only been partially addressed:

androidx.navigation:navigation-runtime:2.6.0-alpha08

yu...@gmail.com <yu...@gmail.com> #9Aug 13, 2021 04:42AM

So I debugged more using the sample I previously provided and it seems like it's related to this, although it only happens when using flowWithLifecycle as described here: https://medium.com/androiddevelopers/a-safer-way-to-collect-flows-from-android-uis-23080b1f8bda.

Attaching the sample that shows the problems and the video.

In sample view model, there is simple flow that emits text in some interval.

In 2.4.0-alpha04 - Collecting flow directly via collectAsState or via rememberFlowWithLifecycle works as expected (interval Flow doesn't complete until the user leaves the screen)

In 2.4.0-alpha05-06 - Screen becomes empty tab reselection

In Snapshot #7634339:

Tab reselection doesn't cause empty screens.
Tab reselection doesn't cause early flow completion when collecting interval flow directly via collectAsState
Tab reselection does cause early flow completion when collecting interval flow wrapped rememberFlowWithLifecycle (as show in attached video)

NavigationComposeBug-Flows.zip

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screen-20210812-232537.mp4

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ro...@gmail.com <ro...@gmail.com> #10Aug 27, 2023 04:09AM

This is really weird but I believe this issue resurfaced in 2.7.1. I was using 2.5.3 and it was working just fine but today i updated the dependency and this started happening.

mi...@gmail.com <mi...@gmail.com> #11Sep 5, 2023 11:26AM

Same for me. I was using 2.7.1. When I selected the arrow to navigate back twice quickly, the app would go back one screen, then the screen would go completely blank. When I reverted to 2.5.3, that issue went away.

so...@gmail.com <so...@gmail.com> #12Sep 20, 2023 09:36AM

Same for me. I was using 2.7.2 and, oh man, when I encountered this issue I didn't even know where to start debugging. Thank god it worked just fine when I downgraded to 2.5.3.

jb...@google.com <jb...@google.com> #13Sep 25, 2023 03:34PM

Please file a new bug with a minimal sample project that reproduces this issue.

mi...@gmail.com <mi...@gmail.com> #14Oct 6, 2023 09:56AM

same here, just updated from 2.5.3 to 2.7.3 and screen is blank when navigating for second time on same screen

de...@gmail.com <de...@gmail.com> #15Feb 2, 2024 01:38AM

To reproduce this issue, I attached a basic navigation project that consists of screens with buttons that go from one Screen to another.

Additionally, I attached two videos. One using Navigation 2.6.0 shows it is working fine, while the other video using Navigation 2.7.1 shows the strange behavior of a blank flash.

I tested all 2.7.x versions and the 2.8.0 alpha, and it's still happening.

Additionally, in some cases, the transition of the screens is that it enters from the upper right corner to the lower left. This behavior is bizarre and erratic since there is no defined animation, and it happens randomly on the screen. Only when many buttons on the screens are pressed quickly.

Feel free to tag me if there is any advance :(. (I am new here, IDK how this works)

JustSimpleExample.rar

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Using Navigation 2.6.0.mp4

5.3 MB

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Using Navigation 2.7.1.mp4

7.9 MB

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yu...@gmail.com <yu...@gmail.com> #16Feb 2, 2024 02:20AM

#15 you should report this in a new ticket

ja...@gmail.com <ja...@gmail.com> #17Oct 13, 2024 12:26PM

Here is a solution that works for me. The blank screen seems to happen if there's no screen in the previous history to navigate to when a user double-clicks the back arrow too quickly.

if (navController.previousBackStackEntry != null) {
navController.popBackStack()
}

ja...@gmail.com <ja...@gmail.com> #18Oct 13, 2024 02:19PM

And here is my solution for bottom navigation, always check if the current route is not equal to the route being navigated to:

onClick = {
if (selectedItemIndex != index) {
localNavController.navigate(
route = item.route,
builder = {
launchSingleTop = true
restoreState = true
popUpTo(localNavController.graph.startDestinationId) {
saveState = true
}
}
)
}
}

Message last modified on Oct 13, 2024 02:20PM

Issue 194925622

Description

Issue summary

Comments

il...@google.com <il...@google.com> #2Jul 28, 2021 10:56PM

yu...@gmail.com <yu...@gmail.com> #3Jul 28, 2021 11:59PM

il...@google.com <il...@google.com> Jul 29, 2021 12:09AM

m....@futuremind.com <m....@futuremind.com> #4Jul 29, 2021 09:51AM

co...@protonmail.com <co...@protonmail.com> #5Aug 5, 2021 05:10AM

ap...@google.com <ap...@google.com> #6Aug 12, 2021 12:16AM

jb...@google.com <jb...@google.com> #7Aug 12, 2021 03:02AM

yu...@gmail.com <yu...@gmail.com> #8Aug 13, 2021 03:52AM

yu...@gmail.com <yu...@gmail.com> #9Aug 13, 2021 04:42AM

ro...@gmail.com <ro...@gmail.com> #10Aug 27, 2023 04:09AM

mi...@gmail.com <mi...@gmail.com> #11Sep 5, 2023 11:26AM

so...@gmail.com <so...@gmail.com> #12Sep 20, 2023 09:36AM

jb...@google.com <jb...@google.com> #13Sep 25, 2023 03:34PM

mi...@gmail.com <mi...@gmail.com> #14Oct 6, 2023 09:56AM

de...@gmail.com <de...@gmail.com> #15Feb 2, 2024 01:38AM

yu...@gmail.com <yu...@gmail.com> #16Feb 2, 2024 02:20AM

ja...@gmail.com <ja...@gmail.com> #17Oct 13, 2024 12:26PM

ja...@gmail.com <ja...@gmail.com> #18Oct 13, 2024 02:19PM

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