[Solved] ViewPager.setAdapter throws IllegalArgumentException in Android

 ViewPager.setAdapter throws IllegalArgumentException in Android

java.lang.IllegalArgumentException

at androidx.core.util.Preconditions.checkArgument(Preconditions.java:38)

at androidx.viewpager2.adapter.FragmentStateAdapter.onAttachedToRecyclerView(FragmentStateAdapter.java:132)

at androidx.recyclerview.widget.RecyclerView.setAdapterInternal(RecyclerView.java:1243)

at androidx.recyclerview.widget.RecyclerView.setAdapter(RecyclerView.java:1194)

at androidx.viewpager2.widget.ViewPager2.setAdapter(ViewPager2.java:461)

at net.twobeone.pink.fragments.MainFragment.activityInit(MainFragment.kt:58)

at net.twobeone.pink.fragments.MainFragment.onViewCreated(MainFragment.kt:49)

at androidx.fragment.app.Fragment.performViewCreated(Fragment.java:3128)

at androidx.fragment.app.FragmentStateManager.createView(FragmentStateManager.java:552)

at androidx.fragment.app.FragmentStateManager.moveToExpectedState(FragmentStateManager.java:261)

at androidx.fragment.app.FragmentManager.executeOpsTogether(FragmentManager.java:1890)

at androidx.fragment.app.FragmentManager.removeRedundantOperationsAndExecute(FragmentManager.java:1823)

at androidx.fragment.app.FragmentManager.execPendingActions(FragmentManager.java:1760)

at androidx.fragment.app.FragmentManager$5.run(FragmentManager.java:547)

at android.os.Handler.handleCallback(Handler.java:938)

at android.os.Handler.dispatchMessage(Handler.java:99)

at android.os.Looper.loop(Looper.java:246)

at android.app.ActivityThread.main(ActivityThread.java:8653)

at java.lang.reflect.Method.invoke(Native Method)

at com.android.internal.os.RuntimeInit$MethodAndArgsCaller.run(RuntimeInit.java:602)

at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:1130)

Solution : 

Initialize ViewPagerAdapter in onCreateView.

Wrong Example:

class MainFragment : BaseFragment<FragmentMainBinding>() {
    
    private val viewPagerAdapter : ViewPagerAdapter by lazy { ExampleViewPagerAdapter(this) }
    
}

vallayoutResID 재정의: Int get() = R.layout.fragment_main

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