Android 在自定义LayoutManager（扩展RecyclerView.LayoutManager）中，RecyclerView.getChildViewHolderInt NullPointerException问题

尝试类似于此（简化版本）的操作后：

我有一个例外：

    java.lang.NullPointerException
        at android.support.v7.widget.RecyclerView.getChildViewHolderInt(RecyclerView.java:2497)
        at android.support.v7.widget.RecyclerView$LayoutManager.addViewInt(RecyclerView.java:4807)
        at android.support.v7.widget.RecyclerView$LayoutManager.addView(RecyclerView.java:4803)
        at android.support.v7.widget.RecyclerView$LayoutManager.addView(RecyclerView.java:4791)

---

如果没有ViewHolder，我无法添加到RecyclerView子视图

决不能直接在布局管理器中将新的子项添加到RecyclerView中。它添加的视图应始终从附加的RecyclerView.Adapter中获取，以便对它们进行正确说明并附加有效的ViewHolder

    java.lang.NullPointerException
        at android.support.v7.widget.RecyclerView.getChildViewHolderInt(RecyclerView.java:2497)
        at android.support.v7.widget.RecyclerView$LayoutManager.addViewInt(RecyclerView.java:4807)
        at android.support.v7.widget.RecyclerView$LayoutManager.addView(RecyclerView.java:4803)
        at android.support.v7.widget.RecyclerView$LayoutManager.addView(RecyclerView.java:4791)