Attempt to write to field 'int android.support.v7.widget.RecyclerView$ViewHolder.mItemViewType' on a

异常Logcat:

Process: com.atguigu.shoppingmall, PID: 11093
   java.lang.NullPointerException: Attempt to write to field 'int android.support.v7.widget.RecyclerView$ViewHolder.mItemViewType' on a null object reference
   at android.support.v7.widget.RecyclerView$Adapter.createViewHolder(RecyclerView.java:5834)
   at android.support.v7.widget.RecyclerView$Recycler.getViewForPosition(RecyclerView.java:5057)
   at android.support.v7.widget.RecyclerView$Recycler.getViewForPosition(RecyclerView.java:4967)
   at android.support.v7.widget.LinearLayoutManager$LayoutState.next(LinearLayoutManager.java:2029)
   at android.support.v7.widget.GridLayoutManager.layoutChunk(GridLayoutManager.java:541)
   at android.support.v7.widget.LinearLayoutManager.fill(LinearLayoutManager.java:1377)
   at android.support.v7.widget.LinearLayoutManager.onLayoutChildren(LinearLayoutManager.java:578)
   at android.support.v7.widget.GridLayoutManager.onLayoutChildren(GridLayoutManager.java:170)
   at android.support.v7.widget.RecyclerView.dispatchLayoutStep2(RecyclerView.java:3315)
   at android.support.v7.widget.RecyclerView.dispatchLayout(RecyclerView.java:3124)
   at android.support.v7.widget.RecyclerView.onLayout(RecyclerView.java:3568)
   at android.view.View.layout(View.java:15596)
   at android.view.ViewGroup.layout(ViewGroup.java:4966)
   at android.widget.RelativeLayout.onLayout(RelativeLayout.java:1076)
   at android.view.View.layout(View.java:15596)
   at android.view.ViewGroup.layout(ViewGroup.java:4966)
   at android.widget.FrameLayout.layoutChildren(FrameLayout.java:573)
   at android.widget.FrameLayout.onLayout(FrameLayout.java:508)
   at android.view.View.layout(View.java:15596)
   at android.view.ViewGroup.layout(ViewGroup.java:4966)
   at android.widget.LinearLayout.setChildFrame(LinearLayout.java:1703)
   at android.widget.LinearLayout.layoutVertical(LinearLayout.java:1557)
   at android.widget.LinearLayout.onLayout(LinearLayout.java:1466)
   at android.view.View.layout(View.java:15596)
   at android.view.ViewGroup.layout(ViewGroup.java:4966)
   at android.widget.FrameLayout.layoutChildren(FrameLayout.java:573)
   at android.widget.FrameLayout.onLayout(FrameLayout.java:508)
   at android.view.View.layout(View.java:15596)Process: com.atguigu.shoppingmal