Viewpager2 FragmentStateAdapter leak

[PierreFourreau]

Hi,

I implement a basic viewpager2

My main fragment (which contain a viewpager of 2 fragments (fragmentA and fragment B))

...
 override fun onViewCreated(view: View, savedInstanceState: Bundle?) {
 my_view_pager.adapter = MyAdapter(activity, args.refBrand)
        TabLayoutMediator(my_tab_layout, view_pager) { tab, position ->
            tab.text = if(position == 0) "1" else "2"
        }.attach()
}
...

Adapter :

class MyAdapter : FragmentStateAdapter(fragmentActivity) {

    override fun getItemCount(): Int = 2

    override fun createFragment(position: Int): Fragment = when (position) {
        0 -> FirstFragment.newInstance(filter = true)
        1 -> Second.newInstance(filter = false)
        else -> throw IllegalArgumentException...
    }
}

The FragmentStateAdapter is leaking.

Like my others screens without viewpagers I tried

override fun onDestroyView() {
        super.onDestroyView()
        my_view_pager.adapter = null
    }

But it crash when I go to another fragment destination from fragmentA (or B) and come back :

E/AndroidRuntime: FATAL EXCEPTION: main Process: app, PID: 30471 java.lang.IllegalStateException: Fragment no longer exists for key f#0: unique id 7ee10572-a2f6-4e46-8227-daaad57fd649 at androidx.fragment.app.FragmentManager.getFragment(FragmentManager.java:772) at androidx.viewpager2.adapter.FragmentStateAdapter.restoreState(FragmentStateAdapter.java:549) at androidx.viewpager2.widget.ViewPager2.restorePendingState(ViewPager2.java:350) at androidx.viewpager2.widget.ViewPager2.dispatchRestoreInstanceState(ViewPager2.java:375) at android.view.ViewGroup.dispatchRestoreInstanceState(ViewGroup.java:3864) at android.view.ViewGroup.dispatchRestoreInstanceState(ViewGroup.java:3864) at android.view.View.restoreHierarchyState(View.java:19793) at androidx.fragment.app.Fragment.restoreViewState(Fragment.java:573) at androidx.fragment.app.FragmentStateManager.restoreViewState(FragmentStateManager.java:356) at androidx.fragment.app.FragmentManager.moveToState(FragmentManager.java:1189) at androidx.fragment.app.FragmentManager.addAddedFragments(FragmentManager.java:2224) at androidx.fragment.app.FragmentManager.executeOpsTogether(FragmentManager.java:1997) at androidx.fragment.app.FragmentManager.removeRedundantOperationsAndExecute(FragmentManager.java:1953) at androidx.fragment.app.FragmentManager.execPendingActions(FragmentManager.java:1849) at androidx.fragment.app.FragmentManager$4.run(FragmentManager.java:413) at android.os.Handler.handleCallback(Handler.java:883) at android.os.Handler.dispatchMessage(Handler.java:100) at android.os.Looper.loop(Looper.java:214) at android.app.ActivityThread.main(ActivityThread.java:7356) at java.lang.reflect.Method.invoke(Native Method) at com.android.internal.os.RuntimeInit$MethodAndArgsCaller.run(RuntimeInit.java:492) at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:930)

Can you help? Thanks

[hushino]

Same problem here

[jermgilb]

When using a Navigation Graph which loads a contain fragment which contains FragmentStateAdapter

Its also reported here: https://issuetracker.google.com/issues/154751401

[AleksandarAleksiev]

I had the same problem but it looks like I have found a workaround. In my case, I was adding data to the adapter before attaching it to the ViewPager2 adapter. If I first set the ViewPager2 adapter and then add data then looks like the FragmentStateAdapter is no longer leaking and the app is not crashing

[akelix]

The same problem. My solution: viewPager2.addOnAttachStateChangeListener(object : View.OnAttachStateChangeListener { override fun onViewDetachedFromWindow(v: View) { viewPager2.removeOnAttachStateChangeListener(this) tabLayoutMediator.detach() viewPager2.setup.unregisterOnPageChangeCallback(onPageChangeCallback) viewPager2..adapter = null } })

FragmentStateAdapter is still leaking because it uses lifecycle from mainnavigationfragment. But it uses only 800bytes.

[Rajarml]

Using viewpager.adapter = null in onDestroyView() is causing this issue, removing this line avoid the crash. But nullify the ViewPager's adapter is an attempt to fix the memory leak which should be fixed with a yet unknown efficient manner 😞

[vlasentiy]

You can try to set this layout property for androidx.viewpager2.widget.ViewPager2 android:saveEnabled="false"

[alkocher]

Just create adapter with Fragment: FragmentStateAdapter(fragment)

Don't use FragmentStateAdapter(fragmentActivity)

[OonKhengHuang]

You can try to set this layout property for androidx.viewpager2.widget.ViewPager2 android:saveEnabled="false"

U are my lifesaver! my viewpager was already inside a fragment, and I try the childFragmentManager but the app will crash when I press again, but adding this"savedEnabled=false", it works perfectly!

[hoc081098]

According to https://issuetracker.google.com/issues/151212195#comment3

FragmentStateAdapter(fragment.childFragmentManager, fragment.viewLifecycleOwner.lifecycle)

[VinuPolly-Bonnet]

Has someone found a fix for this issue yet? I have tried quite a few things and only android:saveEnabled="false seems to work, but I need the ViewPager2 to remember the page it is on

[alkocher]

Has someone found a fix for this issue yet? I have tried quite a few things and only android:saveEnabled="false seems to work, but I need the ViewPager2 to remember the page it is on

Try to use FragmentStateAdapter(fragment, lifecycle)

[VinuPolly-Bonnet]

@alkocher thanks, but isn't it same as using FragmentStateAdapter(fragment), because I will be anyways using the host fragments childFragmentManager and hostFragment's lifeCycle. Maybe I am missing something here?

[alkocher]

@alkocher thanks, but isn't it same as using FragmentStateAdapter(fragment), because I will be anyways using the host fragments childFragmentManager and hostFragment's lifeCycle. Maybe I am missing something here?

I use this constructor with fragment.viewLifecycleOwner.lifecycle and set adapter to null when onDestroyView.

[VinuPolly-Bonnet]

@alkocher thanks, will try this out 🙌

[DiamondIT7]

You can try to set this layout property for androidx.viewpager2.widget.ViewPager2 android:saveEnabled="false"

brooooo you saved my time and nerves today!

[MINTHANHTIKE25]

You can try to set this layout property for androidx.viewpager2.widget.ViewPager2 android:saveEnabled="false"

Thank you for this . Finally, I can fix it.

[AlyonaRulezzz]

Just create adapter with Fragment: FragmentStateAdapter(fragment)

Don't use FragmentStateAdapter(fragmentActivity)

It didn't help in my case(

[HeXioahei]

You can try to set this layout property for androidx.viewpager2.widget.ViewPager2 android:saveEnabled="false"

Thanks！