v7 RecyclerView.computeVerticalScrollRange() gives NullPointerException

问题

i am getting

Fatal Exception: java.lang.NullPointerException
   at android.support.v7.widget.RecyclerView.computeVerticalScrollRange(SourceFile:1654)
   at android.view.View.onDrawScrollBars(View.java:12160)
   at android.view.View.draw(View.java:14742)
   at android.support.v7.widget.RecyclerView.draw(SourceFile:3097)
   at android.view.View.getDisplayList(View.java:13588)
   at android.view.View.getDisplayList(View.java:13635)
   at android.view.View.draw(View.java:14430)
   at android.view.ViewGroup.drawChild(ViewGroup.java:3252)
   at android.view.ViewGroup.dispatchDraw(ViewGroup.java:3070)
   at android.view.View.draw(View.java:14739)
   at android.view.View.getDisplayList(View.java:13588)
   at android.view.View.getDisplayList(View.java:13635)
   at android.view.View.draw(View.java:14430)
   at android.view.ViewGroup.drawChild(ViewGroup.java:3252)
   at android.view.ViewGroup.dispatchDraw(ViewGroup.java:3070)
   at android.view.View.draw(View.java:14739)
   at android.widget.FrameLayout.draw(FrameLayout.java:534)

this crash but this is not happing always . some user getting this crash . i tried with different scenario i haven't got this crash

my code is

 adapter = new HAdapter(getContext(), mList);
        LinearLayoutManager layoutManager = new     LinearLayoutManager(getContext());
        list.setLayoutManager(layoutManager);
        list.addItemDecoration(new VerticalSpaceItemDecoration(5));
        list.setAdapter(adapter);
        layoutManager.scrollToPosition(2);

   compile ('com.android.support:recyclerview-v7:23.1.1'){
    force = true;
      }

my xml is

  <android.support.v7.widget.RecyclerView
    android:id="@+id/recycler"
    android:layout_width="match_parent"
    android:layout_height="match_parent"

    android:layout_marginBottom="15dp"
    android:layout_marginLeft="15dp"
    android:layout_marginRight="15dp"
    android:textAlignment="center"

    android:visibility="visible" />

any idea why this crash is happing

来源：https://stackoverflow.com/questions/38781896/v7-recyclerview-computeverticalscrollrange-gives-nullpointerexception