OnDestinationChangedListener won't get called if it navigates somewhere in response to current destination. [190228815]

Fixed

Bug

Status Update

No update yet.

Description

sh...@google.com

created issue #1

Jun 4, 2021 10:40PM

Component used: Navigation Version used: 2.3.5 Devices/Android versions reproduced on: Irrelevant ;)

Repro steps:

In a OnDestinationChangedListener, set things up so that if the new destination is A, nav to B.
Set the current destination to A.
Add the OnDestinationChangedListener to the NavController.

Expected Result: OnDestinationChangedListener receives callback when it is set, and then receives a callback when it causes navigation to B.

Actual Result: OnDestinationChangedListener receives callback when it is set, and then DOES NOT receive a callback when it causes navigation to B.

After the OnDestinationChangedListener is set, this sort of reentrant call works as would be expected, but when getting the callback after having set the OnDestinationChangedListener, it does not.

I think this simply requires swapping

mOnDestinationChangedListeners.add(listener);

and

if (!mBackStack.isEmpty()) {
            NavBackStackEntry backStackEntry = mBackStack.peekLast();
            listener.onDestinationChanged(this, backStackEntry.getDestination(),
                    backStackEntry.getArguments());
        }

in NavController.java. :)

Comments

il...@google.com <il...@google.com> #2Jun 4, 2021 10:57PM

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.

il...@google.com <il...@google.com> Jun 8, 2021 07:26PM

Assigned to il...@google.com.

il...@google.com <il...@google.com> Jun 9, 2021 12:00AM

Accepted by il...@google.com.

ap...@google.com <ap...@google.com> #3Jun 9, 2021 03:05AM

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

il...@google.com <il...@google.com> #4Jun 9, 2021 03:42AM

Marked as fixed.

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.

sh...@google.com <sh...@google.com> #5Jun 11, 2021 05:07PM

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.

Issue 190228815