androidx.navigation:navigation-*:2.4.0-alpha01 crashes with ConcurrentModificationException [188860458]

Fixed

Bug

Status Update

No update yet.

Description

co...@protonmail.com

created issue #1

May 21, 2021 04:22AM

Component used: Navigation Version used: androidx.navigation:navigation-*:2.4.0-alpha01 Devices/Android versions reproduced on:

I don't have a repro project, but I do have a stacktrace:

2021-05-21 00:19:31.604 12663-12663/com.rollertoaster.app E/AndroidRuntime: FATAL EXCEPTION: main
    Process: com.rollertoaster.app, PID: 12663
    java.util.ConcurrentModificationException
        at java.util.ArrayList$Itr.next(ArrayList.java:860)
        at androidx.navigation.NavController.dispatchOnDestinationChanged(NavController.kt:703)
        at androidx.navigation.NavController.navigate(NavController.kt:1421)
        at androidx.navigation.NavController.navigate(NavController.kt:1200)
        at androidx.navigation.NavController.navigate(NavController.kt:1128)
        at androidx.navigation.ui.NavigationUI.onNavDestinationSelected(NavigationUI.kt:90)
        at androidx.navigation.ui.NavigationUI$setupWithNavController$3.onNavigationItemSelected(NavigationUI.kt:392)
        at com.google.android.material.navigation.NavigationView$1.onMenuItemSelected(NavigationView.java:217)
        at androidx.appcompat.view.menu.MenuBuilder.dispatchMenuItemSelected(MenuBuilder.java:834)
        at androidx.appcompat.view.menu.MenuItemImpl.invoke(MenuItemImpl.java:158)
        at androidx.appcompat.view.menu.MenuBuilder.performItemAction(MenuBuilder.java:985)
        at com.google.android.material.internal.NavigationMenuPresenter$1.onClick(NavigationMenuPresenter.java:416)
        at android.view.View.performClick(View.java:7448)
        at android.view.View.performClickInternal(View.java:7425)
        at android.view.View.access$3600(View.java:810)
        at android.view.View$PerformClick.run(View.java:28305)
        at android.os.Handler.handleCallback(Handler.java:938)
        at android.os.Handler.dispatchMessage(Handler.java:99)
        at android.os.Looper.loop(Looper.java:223)
        at android.app.ActivityThread.main(ActivityThread.java:7656)
        at java.lang.reflect.Method.invoke(Native Method)
        at com.android.internal.os.RuntimeInit$MethodAndArgsCaller.run(RuntimeInit.java:592)
        at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:947)

Comments

jb...@google.com <jb...@google.com> #2May 21, 2021 03:32PM

You don't need to do step 1 or 2 - ensuring you've called addNavigator() before setGraph() is enough.

Specifically, see

https://issuetracker.google.com/issues/110763345#comment2

Also mentioned is the fact that you can override createFragmentNavigator(), call navController.navigatorProvider.addNavigator() there, then return super.createFragmentNavigator().

il...@google.com <il...@google.com> #3May 21, 2021 04:25PM

Assigned to jb...@google.com.

It's may also be of interest that I am making use of a custom navigator to implement conditional routing. My custom destination/nodes simply implement an interface like this:
interface DynamicNode {
@IdRes
fun getDestination(context: Context, @IdRes destinationIn: Int, argsIn: Bundle?) : Int
}

The Navigator then implements a navigate method that simply calls NavController.navigate using the ID returned by the DynamicNode and returns null, essentially performing a redirect. It would be cool to see something like this baked-in with a later version of the Navigation component.

zo...@gmail.com <zo...@gmail.com> #4May 21, 2021 08:44PM

>> You don't need to do step 1 or 2 - ensuring you've called addNavigator() before setGraph() is enough.

Ah gotcha. Okay that's a nicer then. Thanks!

ap...@google.com <ap...@google.com> #5May 24, 2021 08:29PM

Project: platform/frameworks/support
Branch: androidx-master-dev

commit 238c09170a34e1c94af42bc3c6e9fce551883aef
Author: Ian Lake <ilake@google.com>
Date: Mon Apr 22 12:54:51 2019

Rename createFragmentNavigator()

Fix confusion around what method should
be overriden to add custom Navigators to
a NavHostFragment.

Test: tested in testapp
Fixes: 122802849
Change-Id: I969dca429a62e0533cb4ca93c77e68e062278a6f

M navigation/fragment/api/2.1.0-alpha03.txt
M navigation/fragment/api/current.txt
M navigation/fragment/src/main/java/androidx/navigation/fragment/NavHostFragment.java

https://android-review.googlesource.com/947645

https://goto.google.com/android-sha1/238c09170a34e1c94af42bc3c6e9fce551883aef

jb...@google.com <jb...@google.com> #6May 26, 2021 09:03PM

Marked as fixed.

We've decided to rename createFragmentNavigator() to onCreateNavController(NavController) to make it more clear that this is something you can override to get a callback for when the NavController is created.

This will be available in Navigation 2.1.0-alpha03

Issue 188860458