當RecyclerView遇到Inconsistency detected崩潰時

近來項目裏，RecyclerView更新數據偶爾出現crash，錯誤日誌如下：

java.lang.IndexOutOfBoundsException: Inconsistency detected. Invalid view holder adapter positionViewHolder{2064e5c6 position=2 id=-1, oldPos=2, pLpos:-1 scrap [attachedScrap] tmpDetached no parent}
at android.support.v7.widget.RecyclerView$Recycler.validateViewHolderForOffsetPosition(RecyclerView.java:4505)
at android.support.v7.widget.RecyclerView$Recycler.getViewForPosition(RecyclerView.java:4636)
at android.support.v7.widget.RecyclerView$Recycler.getViewForPosition(RecyclerView.java:4617)
at android.support.v7.widget.LinearLayoutManager$LayoutState.next(LinearLayoutManager.java:1994)
at android.support.v7.widget.LinearLayoutManager.layoutChunk(LinearLayoutManager.java:1390)
at android.support.v7.widget.LinearLayoutManager.fill(LinearLayoutManager.java:1353)
at android.support.v7.widget.LinearLayoutManager.onLayoutChildren(LinearLayoutManager.java:574)
at android.support.v7.widget.RecyclerView.dispatchLayoutStep1(RecyclerView.java:2979)
at android.support.v7.widget.RecyclerView.dispatchLayout(RecyclerView.java:2904)
at android.support.v7.widget.RecyclerView.onLayout(RecyclerView.java:3283)
at android.view.View.layout(View.java:15912)
at android.view.ViewGroup.layout(ViewGroup.java:5108)
at android.widget.LinearLayout.setChildFrame(LinearLayout.java:1959)
at android.widget.LinearLayout.layoutHorizontal(LinearLayout.java:1948)
at android.widget.LinearLayout.onLayout(LinearLayout.java:1724)
at android.view.View.layout(View.java:15912)
at android.view.ViewGroup.layout(ViewGroup.java:5108)
at android.widget.LinearLayout.setChildFrame(LinearLayout.java:1959)
at android.widget.LinearLayout.layoutVertical(LinearLayout.java:1813)
at android.widget.LinearLayout.onLayout(LinearLayout.java:1722)
at android.view.View.layout(View.java:15912)
at android.view.ViewGroup.layout(ViewGroup.java:5108)
at android.widget.FrameLayout.layoutChildren(FrameLayout.java:633)
at android.widget.FrameLayout.onLayout(FrameLayout.java:568)
at android.view.View.layout(View.java:15912)
at android.view.ViewGroup.layout(ViewGroup.java:5108)
at android.widget.LinearLayout.setChildFrame(LinearLayout.java:1959)
at android.widget.LinearLayout.layoutVertical(LinearLayout.java:1813)
at android.widget.LinearLayout.onLayout(LinearLayout.java:1722)
at android.view.View.layout(View.java:15912)
at android.view.ViewGroup.layout(ViewGroup.java:5108)
at android.widget.FrameLayout.layoutChildren(FrameLayout.java:633)
at android.widget.FrameLayout.onLayout(FrameLayout.java:568)
at android.view.View.layout(View.java:15912)
at android.view.ViewGroup.layout(ViewGroup.java:5108)
at android.widget.FrameLayout.layoutChildren(FrameLayout.java:633)
at android.widget.FrameLayout.onLayout(FrameLayout.java:568)
at android.view.View.layout(View.java:15912)
at android.view.ViewGroup.layout(ViewGroup.java:5108)
at android.widget.LinearLayout.setChildFrame(LinearLayout.java:1959)
at android.widget.LinearLayout.layoutVertical(LinearLayout.java:1813)
at android.widget.LinearLayout.onLayout(LinearLayout.java:1722)
at android.view.View.layout(View.java:15912)
at android.view.ViewGroup.layout(ViewGroup.java:5108)
at android.widget.FrameLayout.layoutChildren(FrameLayout.java:633)
at android.widget.FrameLayout.onLayout(FrameLayout.java:568)
at android.view.View.layout(View.java:15912)
at android.view.ViewGroup.layout(ViewGroup.java:5108)
at android.widget.FrameLayout.layoutChildren(FrameLayout.java:633)
at android.widget.FrameLayout.onLayout(FrameLayout.java:568)
at android.view.View.layout(View.java:15912)
at android.view.ViewGroup.layout(ViewGroup.java:5108)
at android.widget.FrameLayout.layoutChildren(FrameLayout.java:633)
at android.widget.FrameLayout.onLayout(FrameLayout.java:568)
at android.view.View.layout(View.java:15912)
at android.view.ViewGroup.layout(ViewGroup.java:5108)
at android.widget.LinearLayout.setChildFrame(LinearLayout.java:1959)
at android.widget.LinearLayout.layoutVertical(LinearLayout.java:1813)
at android.widget.Line  

遇到這類錯誤java.lang.IndexOutOfBoundsException: Inconsistency detected. Invalid view holder adapter positionViewHolder，通過查閱Stackoverflow和資料，總結了如下情況和解決方法：

方法一

自己寫一個繼承LinearLayoutManager的包裝類，在onLayoutChildren()方法裏try-catch捕獲該異常。

@Override
public void onLayoutChildren(RecyclerView.Recycler recycler, RecyclerView.State state) {
    try {
        super.onLayoutChildren(recycler, state);
    } catch (IndexOutOfBoundsException e) {
        e.printStackTrace();
    }
}

方法二

在進行數據移除和數據增加時，務必要保證RecyclerView的Adapter中的數據集和移除／添加等操作後的數據集保持一致！

這裏，前者是在該Adapter內部，不妨叫做內部數據集，後者是開發人員傳過給Adapter的，不妨叫外部數據集。更新RecyclerView數據時，需要保證外部數據集和內部數據集實時保持一致。

外部數據集同步到內部數據集，使用如下的方法：

• notifyItemRangeRemoved();
• notifyItemRangeInserted();
• notifyItemRangeChanged();
• notifyDataSetChanged();

這裏對notifyDataSetChange()做些說明：
使用該方法的更新內部數據集，沒有默認的動畫效果，同時更新數據的效率頁不如上面的方法，官方不推薦使用這種方式更新數據集。

Don’t call notifyDataSetChanged if you don’t have to.

RecyclerView的Adapter裏，發生異常的錯誤代碼如下：

public void notifyData(List<PoiItem> poiItemList) {
    if (poiItemList != null ) {
        mPoiItems.clear();
        mPoiItems.addAll(poiItemList);
        notifyItemRangeChanged(0, poiItemList.size());
    }
}

錯誤分析：
mPoiItems是外部數據集，對該外部數據集做了兩個操作：先移除數據，然後添加數據，之後notify數據集。這裏，添加數數據時（Adapter的內部數據集內容還處在外部數據集移除數據之前），造成了內部和外部數據集不一致。

這是一方面，另一方面，我使用了notifyItemRangeChanged()來更新數據，如果poiItemList傳過來的新數據和原來mPoiItems的數據數量不一致，就會出現內部數據集和外部數據在同步後不一致，從而報錯。

修復後，運行正常的代碼如下：

public void notifyData(List<PoiItem> poiItemList) {
    if (poiItemList != null) {
        int previousSize = mPoiItems.size();
        mPoiItems.clear();
        notifyItemRangeRemoved(0, previousSize);
        mPoiItems.addAll(poiItemList);
        notifyItemRangeInserted(0, poiItemList.size());
    }
}

修複分析：

每次對外部數據集做改動時，主動和內部數據集做一次同步操作，動畫效果也得到了保持（使用方法三，動畫效果缺失）

方法三：

使用notifyDataSetChanged同步外部數據集和內部數據集。該方法簡單，但是失去了動畫效果，並且更新數據的性能低

use notifyDataSetChanged() will avoid this crash, but it will kill Animation and Performance.

參考文章:

1.stackoverflow 1

2.RecyclerView Bug：IndexOutOfBoundsException: Inconsistency detected. Invalid view holder adapter的解決方案

3.使用RecyclerView遇到的一些問題 Inconsistency detected