Я не могу воспроизвести эту проблему самостоятельно, но я замечаю эту проблему в производстве с Xiaomi MI 9 под управлением Android 10. Вот версии ViewPager2 и RecyclerView, которые я использую:
androidx.recyclerview:recyclerview:1.1.0
androidx.viewpager2:viewpager2:1.0.0
А вот и трассировка стека:
Fatal Exception: java.lang.IllegalStateException: Design assumption violated.
at androidx.viewpager2.adapter.FragmentStateAdapter.placeFragmentInViewHolder(FragmentStateAdapter.java:287)
at androidx.viewpager2.adapter.FragmentStateAdapter.onViewAttachedToWindow(FragmentStateAdapter.java:276)
at androidx.viewpager2.adapter.FragmentStateAdapter.onViewAttachedToWindow(FragmentStateAdapter.java:67)
at androidx.recyclerview.widget.RecyclerView.dispatchChildAttached(RecyclerView.java:7556)
at androidx.recyclerview.widget.RecyclerView$5.addView(RecyclerView.java:860)
at androidx.recyclerview.widget.ChildHelper.addView(ChildHelper.java:107)
at androidx.recyclerview.widget.RecyclerView$LayoutManager.addViewInt(RecyclerView.java:8601)
at androidx.recyclerview.widget.RecyclerView$LayoutManager.addView(RecyclerView.java:8559)
at androidx.recyclerview.widget.LinearLayoutManager.layoutChunk(LinearLayoutManager.java:1643)
at androidx.recyclerview.widget.LinearLayoutManager.fill(LinearLayoutManager.java:1587)
at androidx.recyclerview.widget.LinearLayoutManager.onLayoutChildren(LinearLayoutManager.java:675)
at androidx.recyclerview.widget.RecyclerView.dispatchLayoutStep2(RecyclerView.java:4134)
at androidx.recyclerview.widget.RecyclerView.dispatchLayout(RecyclerView.java:3851)
at androidx.recyclerview.widget.RecyclerView.onLayout(RecyclerView.java:4404)
at android.view.View.layout(View.java:21963)
at android.view.ViewGroup.layout(ViewGroup.java:6317)
at androidx.viewpager2.widget.ViewPager2.onLayout(ViewPager2.java:527)
at android.view.View.layout(View.java:21963)
at android.view.ViewGroup.layout(ViewGroup.java:6317)
at androidx.constraintlayout.widget.ConstraintLayout.onLayout(ConstraintLayout.java:1915)
at android.view.View.layout(View.java:21963)
at android.view.ViewGroup.layout(ViewGroup.java:6317)
at android.widget.FrameLayout.layoutChildren(FrameLayout.java:332)
at android.widget.FrameLayout.onLayout(FrameLayout.java:270)
at android.view.View.layout(View.java:21963)
at android.view.ViewGroup.layout(ViewGroup.java:6317)
at android.widget.FrameLayout.layoutChildren(FrameLayout.java:332)
at android.widget.FrameLayout.onLayout(FrameLayout.java:270)
at android.view.View.layout(View.java:21963)
at android.view.ViewGroup.layout(ViewGroup.java:6317)
at android.widget.FrameLayout.layoutChildren(FrameLayout.java:332)
at android.widget.FrameLayout.onLayout(FrameLayout.java:270)
at android.view.View.layout(View.java:21963)
at android.view.ViewGroup.layout(ViewGroup.java:6317)
at android.widget.LinearLayout.setChildFrame(LinearLayout.java:1829)
at android.widget.LinearLayout.layoutVertical(LinearLayout.java:1673)
at android.widget.LinearLayout.onLayout(LinearLayout.java:1582)
at android.view.View.layout(View.java:21963)
at android.view.ViewGroup.layout(ViewGroup.java:6317)
at android.widget.FrameLayout.layoutChildren(FrameLayout.java:332)
at android.widget.FrameLayout.onLayout(FrameLayout.java:270)
at com.android.internal.policy.DecorView.onLayout(DecorView.java:803)
at android.view.View.layout(View.java:21963)
at android.view.ViewGroup.layout(ViewGroup.java:6317)
at android.view.ViewRootImpl.performLayout(ViewRootImpl.java:3144)
at android.view.ViewRootImpl.performTraversals(ViewRootImpl.java:2654)
at android.view.ViewRootImpl.doTraversal(ViewRootImpl.java:1782)
at android.view.ViewRootImpl$TraversalRunnable.run(ViewRootImpl.java:7785)
at android.view.Choreographer$CallbackRecord.run(Choreographer.java:1031)
at android.view.Choreographer.doCallbacks(Choreographer.java:854)
at android.view.Choreographer.doFrame(Choreographer.java:789)
at android.view.Choreographer$FrameDisplayEventReceiver.run(Choreographer.java:1016)
at android.os.Handler.handleCallback(Handler.java:883)
at android.os.Handler.dispatchMessage(Handler.java:100)
at android.os.Looper.loop(Looper.java:224)
at android.app.ActivityThread.main(ActivityThread.java:7520)
at java.lang.reflect.Method.invoke(Method.java)
at com.android.internal.os.RuntimeInit$MethodAndArgsCaller.run(RuntimeInit.java:539)
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:950)
Я не уверен, откуда это происходит из моего кода, так как трассировка стека не очень понятна. Кроме того, согласно Google Issuetracker, это было решено в viewpager2: 1.0.0-beta03: https://issuetracker.google.com/issues/134246546 с коммитом здесь , но не совсем в моем случае. А вот еще один пост с той же проблемой, на котором не так много полезных ответов: FragmentStateAdapter throws java .lang.IllegalStateException: предположение о проекте нарушено после изменения конфигурации . Было бы здорово, если бы кто-нибудь знал, почему это происходит или как это можно решить.