ViewPager2 crash

Question

I am using Advance Navigation Component with BottomNavigationView.

In One Tab I have ViewPager2. When I clicked on Tab for the first time is working fine.

Although second time come on that tab application keep crashing. Below is crashlog if anyone can help thanks.

java.lang.IllegalArgumentException at androidx.core.util.Preconditions.checkArgument(Preconditions.java:36) at androidx.viewpager2.adapter.FragmentStateAdapter.onAttachedToRecyclerView(FragmentStateAdapter.java:140) at androidx.recyclerview.widget.RecyclerView.setAdapterInternal(RecyclerView.java:1206) at androidx.recyclerview.widget.RecyclerView.setAdapter(RecyclerView.java:1158) at androidx.viewpager2.widget.ViewPager2.setAdapter(ViewPager2.java:460) at com..ui.home.history.HistoryFragment.setupAdapter(HistoryFragment.kt:25) at com..ui.home.history.HistoryFragment.viewSetup(HistoryFragment.kt:21) at com.****.base.BaseFragment.onViewCreated(BaseFragment.kt:37) at androidx.fragment.app.FragmentStateManager.createView(FragmentStateManager.java:332) at androidx.fragment.app.FragmentManager.moveToState(FragmentManager.java:1187) at androidx.fragment.app.FragmentManager.moveToState(FragmentManager.java:1356) at androidx.fragment.app.FragmentManager.moveFragmentToExpectedState(FragmentManager.java:1434) at androidx.fragment.app.FragmentManager.moveToState(FragmentManager.java:1497) at androidx.fragment.app.FragmentManager.dispatchStateChange(FragmentManager.java:2625) at androidx.fragment.app.FragmentManager.dispatchActivityCreated(FragmentManager.java:2577) at androidx.fragment.app.Fragment.performActivityCreated(Fragment.java:2722) at androidx.fragment.app.FragmentStateManager.activityCreated(FragmentStateManager.java:346) at androidx.fragment.app.FragmentManager.moveToState(FragmentManager.java:1188) 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$4.run(FragmentManager.java:413) at android.os.Handler.handleCallback(Handler.java:873) at android.os.Handler.dispatchMessage(Handler.java:99) at android.os.Looper.loop(Looper.java:193) at android.app.ActivityThread.main(ActivityThread.java:6940) at java.lang.reflect.Method.invoke(Native Method) at com.android.internal.os.RuntimeInit$MethodAndArgsCaller.run(RuntimeInit.java:537) at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:858)

Here is my code for fragment :

private val adapter by lazy {
        HistoryPagerAdapter(this)
    }

    override fun viewSetup() {
        binding.vpBuySell.adapter = adapter
        TabLayoutMediator(
            binding.tabBuySell,
            binding.vpBuySell,
            TabLayoutMediator.TabConfigurationStrategy { tab: TabLayout.Tab, i: Int ->
               tab.text = when (i) {
                    0 -> getString(R.string.buy)
                    1 -> getString(R.string.sell)
                    else -> getString(R.string.buy)
                }
            })
    }

Here is ui code :

<androidx.constraintlayout.widget.ConstraintLayout
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:background="@color/blue_122e47">

    <androidx.appcompat.widget.Toolbar
        android:id="@+id/toolbar"
        android:layout_width="match_parent"
        android:layout_height="?actionBarSize"
        android:background="@color/blue_06233e"
        app:layout_constraintEnd_toEndOf="parent"
        app:layout_constraintStart_toStartOf="parent"
        app:layout_constraintTop_toTopOf="parent"
        app:titleTextColor="@color/white">


        <androidx.appcompat.widget.AppCompatTextView
            android:id="@+id/tvTitle"
            style="@style/ToolbarTitleTextStyle"
            android:text="@string/history" />

        <TextView
            android:id="@+id/btnExport"
            android:layout_width="wrap_content"
            android:layout_height="@dimen/_24sdp"
            android:layout_gravity="end"
            android:layout_marginEnd="@dimen/_8sdp"
            android:fontFamily="@font/helvetica_neue_medium"
            android:insetLeft="0dp"
            android:gravity="center"
            android:background="@drawable/shape_export_button"
            android:insetTop="0dp"
            android:insetRight="0dp"
            android:insetBottom="0dp"
            android:foreground="?selectableItemBackground"
            android:paddingBottom="@dimen/_2sdp"
            android:paddingStart="@dimen/_8sdp"
            android:paddingEnd="@dimen/_8sdp"
            android:text="@string/export"
            android:textAllCaps="false"
            android:textColor="@color/white"
            android:textSize="@dimen/_12ssp" />

    </androidx.appcompat.widget.Toolbar>


    <com.google.android.material.tabs.TabLayout
        android:id="@+id/tabBuySell"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:background="@color/blue_122e47"
        app:tabIndicatorFullWidth="false"
        app:tabIndicatorGravity="bottom"
        app:tabTextAppearance="@style/HistoryTabTextStyle"
        app:tabTextColor="@color/gray_697b8b"
        app:tabSelectedTextColor="@color/white"
        app:tabIndicatorHeight="@dimen/_2sdp"
        app:tabIndicatorColor="@color/blue_47cfff"
        app:layout_constraintTop_toBottomOf="@id/toolbar"
        app:tabGravity="start"
        app:tabMode="scrollable" />

    <androidx.viewpager2.widget.ViewPager2
        android:id="@+id/vpBuySell"
        android:layout_width="match_parent"
        android:layout_height="0dp"
        app:layout_constraintBottom_toBottomOf="parent"
        app:layout_constraintTop_toBottomOf="@id/tabBuySell" />
</androidx.constraintlayout.widget.ConstraintLayout>

Here is my adapter code:

class HistoryPagerAdapter(fragment: Fragment) : FragmentStateAdapter(fragment) {
override fun getItemCount(): Int {
    return 2
}
override fun createFragment(position: Int): Fragment {
    return when (position) {
        0 -> HistoryBuyFragment()
        1 -> HistorySellFragment()
        else -> HistoryBuyFragment()
    }
}

}

Answer 1

Actual error is of the lazy initialisation of the adapter. I also don't know why that happened