Inconsistency detected Invalid view holder adapter position"

RecyclerView在新增資料的時候發生了異常.

java.lang.IndexOutOfBoundsException: Inconsistency detected. Invalid view holder adapter positionViewHolder{f82aa71 position=11 id=-1, oldPos=6, pLpos:6 scrap [attachedScrap] tmpDetached not recyclable(1) no parent}
     at android.support.v7.widget.RecyclerView$Recycler.validateViewHolderForOffsetPosition(RecyclerView.java:5297)
     at android.support.v7.widget.RecyclerView$Recycler.tryGetViewHolderForPositionByDeadline(RecyclerView.java:5479)
     at android.support.v7.widget.RecyclerView$Recycler.getViewForPosition(RecyclerView.java:5440)
     at android.support.v7.widget.RecyclerView$Recycler.getViewForPosition(RecyclerView.java:5436)
     at android.support.v7.widget.LinearLayoutManager$LayoutState.next(LinearLayoutManager.java:2224)
     at android.support.v7.widget.LinearLayoutManager.layoutChunk(LinearLayoutManager.java:1551)
     at android.support.v7.widget.LinearLayoutManager.fill(LinearLayoutManager.java:1511)
     at android.support.v7.widget.LinearLayoutManager.onLayoutChildren(LinearLayoutManager.java:595)
     at android.support.v7.widget.RecyclerView.dispatchLayoutStep1(RecyclerView.java:3534)
     at android.support.v7.widget.RecyclerView.dispatchLayout(RecyclerView.java:3310)
  ...
複製程式碼

在RecyclerView#validateViewHolderForOffsetPosition(ViewHolder holder)中

if (holder.mPosition < 0 || holder.mPosition >= mAdapter.getItemCount()) {
                throw new IndexOutOfBoundsException("Inconsistency detected. Invalid view holder "
                        + "adapter position" + holder);
            }
複製程式碼

holder.mPosition >= mAdapter.getItemCount()為真，丟擲了異常發現mAdapter.getItemCount() 的值是正常的，但是holder.mPosition值有問題，在某種情況下和getItemCount的值一樣大，此時條件為真。

接下來看了下RecyclerView中有5個方法改變了mPosition的值,分別是

Adapter#bindViewHolder()
ViewHolder#resetInternal()
ViewHolder#offsetPosition()
ViewHolder#flagRemovedAndOffsetPosition()
Recycler#tryGetViewHolderForPositionByDeadline()

分別打了斷點，發現會引起崩潰的程式碼,會改變mPosition的有其中三個地方resetInternal()，offsetPosition()，bindViewHolder()。 resetInternal() 首先排除，因為mPosition = NO_POSITION;

然後仔細檢視offsetPosition() 和bindViewholder()中的值發現，offsetPosition()的值mPosition += offset;會超出mPosition的值的範圍。所以現在就要去找這個方法被呼叫的時機和offset這個值的含義

檢視offsetPosition()的呼叫,發現呼叫分別來自RecyclerView與RecyclerView.Recycler兩個的對應的insert,move和remove方法,以及ViewHolder的flagRemovedAndOffsetPosition(int, int, boolean)的方法主要看就下面這個

void offsetPositionRecordsForInsert(int positionStart, int itemCount) {
  //...
   //這裡將itemCount 傳遞給了offsetPosition
               holder.offsetPosition(itemCount, false);
 //...
       mRecycler.offsetPositionRecordsForInsert(positionStart, itemCount);
       requestLayout();
   }
複製程式碼

看起來在某個重新整理資料的地方理解錯了itemCount，找到我自己Adapter程式碼裡面的 notifyItemRangeInserted(positionStart,itemCount);暫時修改為notifyDataSetChanged()不會報錯了

Inconsistency detected Invalid view holder adapter position"

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