Fixed

Bug

Status Update

No update yet.

Description

[Deleted User]

created issue #1

Apr 21, 2023 06:57PM

Versions

Component used: Navigation

Version used: 2.5.3

Devices/Android versions reproduced on: any

Description

According to the documentation of [BackHandler], nested BackHandlers(https://developer.android.com/reference/kotlin/androidx/activity/compose/package-summary#top-level-functions) should take priority:

If this is called by nested composables, if enabled, the inner most composable will consume the call to system back and invoke its lambda. The call will continue to propagate up until it finds an enabled BackHandler.

However, this doesn't work correctly if the activity is paused and then resumed.

Steps to reproduce

Start the app
Click back button
Toast "Button clicked" shows
Minimize the app (by pressing home button)
Bring app to foreground (via recent apps menu)
Click back button Expected behavior: Toast "Button clicked" shows Actual behavior: Toast "This should never ever show!!!" shows

Code to demonstrate the issue

class MainActivity : ComponentActivity() {
    override fun onCreate(savedInstanceState: Bundle?) {
        super.onCreate(savedInstanceState)
        setContent {
            MaterialTheme {
                Surface(Modifier.fillMaxSize()) {
                    val context = LocalContext.current
                    BackHandler {
                        Toast.makeText(context, "This should never ever show!!!", Toast.LENGTH_SHORT).show()
                    }
                    SampleApp()
                }
            }
        }
    }
}

@Composable
fun SampleApp() {
    val navController = rememberNavController()
    NavHost(navController, "first") {
        composable("first") { Screen() }
    }
}

@Composable
fun Screen() {
    val context = LocalContext.current
    BackHandler {
        Toast.makeText(context, "Back clicked", Toast.LENGTH_SHORT).show()
    }
    Column {
        Text("First screen")
    }
}

A sample project is attached.

MyApplication.zip

29 MB

Download

Comments

jb...@google.com <jb...@google.com> #2Apr 25, 2023 11:08PM

Great

[Deleted User] <[Deleted User]> #3Apr 25, 2023 11:16PM

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

commit a735aaa4d06c90454de772fae5a02f6cbde210b3
Author: Jeremy Woods <jbwoods@google.com>
Date: Tue Feb 28 22:58:23 2023

Ensure FragmentNavigator destroys intermediate entries on popUpTo

We need to make sure that when Fragment are destroyed their entries are
also always destroyed.

RelNote: "Fixes a regressions in previous release that caused the wrong
BottomNav menu item to be highlighted when using system back to go
between tabs."
Test: Added FragmentNavigatorTest
Bug: 270447657

Change-Id: I634f6047b7016bcb8b690047605a6f66b2dc1438

M navigation/navigation-fragment/src/androidTest/java/androidx/navigation/fragment/FragmentNavigatorTest.kt
M navigation/navigation-fragment/src/main/java/androidx/navigation/fragment/FragmentNavigator.kt

https://android-review.googlesource.com/2461556

il...@google.com <il...@google.com> Apr 26, 2023 11:44PM

Assigned to jb...@google.com.

jb...@google.com <jb...@google.com> #4Apr 27, 2023 12:26AM

This has been fixed internally and will be available in the Navigation 2.6.0-alpha07 release.

ap...@google.com <ap...@google.com> #5Jun 1, 2023 12:50AM

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

commit 96cee05bdb8f61a92e4be00a52b991cfc1ed2f4e
Author: Clara Fok <clarafok@google.com>
Date: Wed Mar 01 12:28:09 2023

Add FragmentNavigator test to assert entry destroyed

Add test to assert that NavBackStackEntry is destroyed after being restored upon recreation/configuration change.

Asserts that the fix on this bug also fixes

b/270610768

.

Test: ./gradlew navigation:navigation-fragment
Bug: 270447657
Change-Id: I8874d2dfaa17e560dd2f6d9da54e435494c187d2

M navigation/navigation-fragment/src/androidTest/java/androidx/navigation/fragment/FragmentNavigatorTest.kt

https://android-review.googlesource.com/2464422

il...@google.com <il...@google.com> #6Jun 1, 2023 05:00PM

Marked as fixed.

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

androidx.navigation:navigation-fragment:2.6.0-alpha07

pr...@google.com <pr...@google.com> #7Jun 8, 2023 01:31AM

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

commit 7cf55857f0db6bd1a1e1f95be7374ed5cf3eca58
Author: Jeremy Woods <jbwoods@google.com>
Date: Wed Mar 15 16:59:50 2023

Fix system back after popUpTo

After you do a popUpTo inclusive while using Navigation with Fragments,
if you attempt to do a system back call, the Navigation back stack is
never updated.

The reason for this is that when fragment views are DESTROYED, we need
for the observer in the FragmentNavigator to update the state so we know
that the entry was already popped.

RelNote: "When using system back after doing a navigate with popUpTo,
the state of the NavController will pop to the correct entry."
Test: Added OnBackPressedTest
Bug: 270447657

Change-Id: I3a8ec072ba6d1655ab054cc081961825909088e6

M navigation/navigation-fragment/src/androidTest/java/androidx/navigation/fragment/OnBackPressedTest.kt
M navigation/navigation-fragment/src/main/java/androidx/navigation/fragment/FragmentNavigator.kt

https://android-review.googlesource.com/2493203

an...@daresay.co <an...@daresay.co> #8Jun 26, 2023 12:35PM

Comment has been deleted.

Message last modified on Jun 26, 2023 12:35PM

li...@gmail.com <li...@gmail.com> #9Jun 26, 2023 12:38PM

I wouldn't say this is fixed. If you add a back-callback in the activity which is lifecycle aware, and then background->foreground the app, the activity back-callback will be put on top of the callback pile. This leads to that any BackHandler in your composable will NOT be triggered.

The best workaround I have for now is to use the non-lifecycle aware function in the activity.

class MainActivity : FragmentActivity() {
    override fun onCreate(savedInstanceState: Bundle?) {
        super.onCreate(savedInstanceState)
        
        // open fragment which hoists the composables
        ...

        if (savedInstanceState == null) {
             onBackPressedDispatcher.addCallback(onBackPressedCallback = someBackHandling())  
            // onBackPressedDispatcher.addCallback(owner = this, onBackPressedCallback = someBackHandling)  // not this one
        }
    }

Message last modified on Jun 26, 2023 12:40PM

ho...@gmail.com <ho...@gmail.com> #10Jul 17, 2023 01:51PM

Comment has been deleted.

Message last modified on Jul 17, 2023 03:43PM

ho...@gmail.com <ho...@gmail.com> #11Jul 17, 2023 02:31PM

Comment has been deleted.

Message last modified on Jul 17, 2023 03:43PM

ho...@gmail.com <ho...@gmail.com> #12Jul 18, 2023 12:10PM

https://developer.android.com/jetpack/androidx/releases/navigation#2.7.0-beta01 :

Bug Fixes : NavHost in Navigation Compose now correctly intercepts system back calls even after the Activity has been STOPPED and RESUMED.

It works fine for me.

Message last modified on Jul 18, 2023 03:45PM

gi...@gmail.com <gi...@gmail.com> #13Sep 22, 2023 12:43PM

I can confirm this is still happening as mentioned in <li...@gmail.com> #9

va...@zedge.net <va...@zedge.net> #14Oct 11, 2023 02:25PM

Still reproduces.
In my case it works fine when the app is first ran, but my custom callback calls navController.popBackStack internally if it can't handle back press on its own. So, when I run the app and click back, everything works, but after I pop up all the Composables from the stack and return to the app, the custom callback is not called anymore.

il...@google.com <il...@google.com> #15Oct 11, 2023 04:45PM

Re comment#14 - please file a new issue with a project that reproduces your problem.

Note that you should never, ever be calling navController.popBackStack() in your own BackHandler as Navigation must be the only one handling its own back stack with the system back button so that Predictive Back works correctly in the future.

ja...@gopuff.com <ja...@gopuff.com> #16Oct 30, 2023 07:13PM

These changes broke our use case to override back handling in navigation library for closing the menu drawer. Please see more details in the issue I've reported.

ja...@sense.com <ja...@sense.com> #17Nov 14, 2024 05:36PM

I believe this is still an issue even without using NavHost like mentioned in comment #16. I filed a new issue here

IssueTracker

BackHandler not working correctly after activity resumes after being paused

Status Update

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Steps to reproduce

Code to demonstrate the issue

Comments

jb...@google.com <jb...@google.com> #2Apr 25, 2023 11:08PM

[Deleted User] <[Deleted User]> #3Apr 25, 2023 11:16PM

il...@google.com <il...@google.com> Apr 26, 2023 11:44PM

jb...@google.com <jb...@google.com> #4Apr 27, 2023 12:26AM

ap...@google.com <ap...@google.com> #5Jun 1, 2023 12:50AM

il...@google.com <il...@google.com> #6Jun 1, 2023 05:00PM

pr...@google.com <pr...@google.com> #7Jun 8, 2023 01:31AM

an...@daresay.co <an...@daresay.co> #8Jun 26, 2023 12:35PM

li...@gmail.com <li...@gmail.com> #9Jun 26, 2023 12:38PM

ho...@gmail.com <ho...@gmail.com> #10Jul 17, 2023 01:51PM

ho...@gmail.com <ho...@gmail.com> #11Jul 17, 2023 02:31PM

ho...@gmail.com <ho...@gmail.com> #12Jul 18, 2023 12:10PM

gi...@gmail.com <gi...@gmail.com> #13Sep 22, 2023 12:43PM

va...@zedge.net <va...@zedge.net> #14Oct 11, 2023 02:25PM

il...@google.com <il...@google.com> #15Oct 11, 2023 04:45PM

ja...@gopuff.com <ja...@gopuff.com> #16Oct 30, 2023 07:13PM

ja...@sense.com <ja...@sense.com> #17Nov 14, 2024 05:36PM

Issue 279118447

Description

Versions

Description

Steps to reproduce

Code to demonstrate the issue

Issue summary

Comments

jb...@google.com <jb...@google.com> #2Apr 25, 2023 11:08PM

[Deleted User] <[Deleted User]> #3Apr 25, 2023 11:16PM

il...@google.com <il...@google.com> Apr 26, 2023 11:44PM

jb...@google.com <jb...@google.com> #4Apr 27, 2023 12:26AM

ap...@google.com <ap...@google.com> #5Jun 1, 2023 12:50AM

il...@google.com <il...@google.com> #6Jun 1, 2023 05:00PM

pr...@google.com <pr...@google.com> #7Jun 8, 2023 01:31AM

an...@daresay.co <an...@daresay.co> #8Jun 26, 2023 12:35PM

li...@gmail.com <li...@gmail.com> #9Jun 26, 2023 12:38PM

ho...@gmail.com <ho...@gmail.com> #10Jul 17, 2023 01:51PM

ho...@gmail.com <ho...@gmail.com> #11Jul 17, 2023 02:31PM

ho...@gmail.com <ho...@gmail.com> #12Jul 18, 2023 12:10PM

gi...@gmail.com <gi...@gmail.com> #13Sep 22, 2023 12:43PM

va...@zedge.net <va...@zedge.net> #14Oct 11, 2023 02:25PM

il...@google.com <il...@google.com> #15Oct 11, 2023 04:45PM

ja...@gopuff.com <ja...@gopuff.com> #16Oct 30, 2023 07:13PM

ja...@sense.com <ja...@sense.com> #17Nov 14, 2024 05:36PM

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