1、出现的3个异常
1.1、第一个,第二个
java.lang.IllegalArgumentException: Called attach on a child which is not detached: ViewHolder{3d34d42 position=4 id=-1, oldPos=-1, pLpos:-1} hy.sohu.com.ui_lib.hyrecyclerview.hyrecyclerView.HyRecyclerView{12f2c6 VFED..... ......ID 0,427-720,1430 #7f0903c6 app:id/hyrecyclerview_chat}, adapter:hy.sohu.com.ui_lib.hyrecyclerview.hyrecyclerView.PullToLoadAdapter@58e3153, layout:hy.sohu.com.ui_lib.hyrecyclerview.HyLinearLayoutManager@9c47a90, context:hy.sohu.com.app.chat.view.message.SingleChatMsgActivity@561df6
at androidx.recyclerview.widget.RecyclerView$5.attachViewToParent(RecyclerView.java:931)
at androidx.recyclerview.widget.ChildHelper.attachViewToParent(ChildHelper.java:241)
at androidx.recyclerview.widget.RecyclerView.addAnimatingView(RecyclerView.java:1443)
at androidx.recyclerview.widget.RecyclerView.animateDisappearance(RecyclerView.java:4371)
at androidx.recyclerview.widget.RecyclerView$4.processDisappeared(RecyclerView.java:617)
at androidx.recyclerview.widget.ViewInfoStore.process(ViewInfoStore.java:245)
at androidx.recyclerview.widget.RecyclerView.dispatchLayoutStep3(RecyclerView.java:4208)
at androidx.recyclerview.widget.RecyclerView.dispatchLayout(RecyclerView.java:3862)
at androidx.recyclerview.widget.RecyclerView.onLayout(RecyclerView.java:4404)
at hy.sohu.com.ui_lib.hyrecyclerview.hyrecyclerView.HyRecyclerView.onLayout(HyRecyclerView.java:1055)
java.lang.IllegalArgumentException: Called removeDetachedView with a view which"
+ " is not flagged as tmp detached." + vh + exceptionLabel()
出现位置与原因： ChildHelper
当向RecyclerView添加一个child时，这个child已经有一个parent。
// mChildHelper = new ChildHelper
public void attachViewToParent(View child, int index,
ViewGroup.LayoutParams layoutParams) {
final ViewHolder vh = getChildViewHolderInt(child);
if (vh != null) {
if (!vh.isTmpDetached() && !vh.shouldIgnore()) {
throw new IllegalArgumentException("Called attach on a child which is not"
+ " detached: " + vh + exceptionLabel());
}
if (DEBUG) {
Log.d(TAG, "reAttach " + vh);
}
vh.clearTmpDetachFlag();
}
RecyclerView.this.attachViewToParent(child, index, layoutParams);
}
1.2、第三个、Cannot call this method while RecyclerView is computing a layout or scrolling HyRecyclerView。
java.lang.IllegalStateException: Cannot call this method while RecyclerView is computing a layout or scrolling hy.sohu.com.ui_lib.hyrecyclerview.hyrecyclerView.HyRecyclerView{62a0245 VFED..... ........ 0,131-1080,1996 #7f0903cd app:id/hyrecyclerview_chat}, adapter:hy.sohu.com.ui_lib.hyrecyclerview.hyrecyclerView.PullToLoadAdapter@2f22d9a, layout:hy.sohu.com.ui_lib.hyrecyclerview.HyLinearLayoutManager@a1e86cb, context:hy.sohu.com.app.chat.view.message.SingleChatMsgActivity@8fe39bf
at androidx.recyclerview.widget.RecyclerView.assertNotInLayoutOrScroll(RecyclerView.java:3062)
at androidx.recyclerview.widget.RecyclerView$RecyclerViewDataObserver.onItemRangeInserted(RecyclerView.java:5558)
at androidx.recyclerview.widget.RecyclerView$AdapterDataObservable.notifyItemRangeInserted(RecyclerView.java:12286)
at androidx.recyclerview.widget.RecyclerView$Adapter.notifyItemRangeInserted(RecyclerView.java:0)
at hy.sohu.com.ui_lib.hyrecyclerview.hyrecyclerView.HeaderAndFooter.HeaderAndFooterRecyclerView$DataObserver.onItemRangeInserted(HeaderAndFooterRecyclerView.java:348)
at androidx.recyclerview.widget.RecyclerView$AdapterDataObservable.notifyItemRangeInserted(RecyclerView.java:12286)
at androidx.recyclerview.widget.RecyclerView$Adapter.notifyItemRangeInserted(RecyclerView.java:0)
at hy.sohu.com.ui_lib.hyrecyclerview.hyadapter.HyBaseNormalAdapter.addData(HyBaseNormalAdapter.java:163)
at hy.sohu.com.app.chat.view.message.ChatMsgBaseActivity.onSaveLocalSuccess(ChatMsgBaseActivity.kt:910)
出现位置与原因：
当调用notifyItemChanged，notifyItemRemove时检测mLayoutOrScrollCounter是否> 0 抛出异常。
private class RecyclerViewDataObserver extends AdapterDataObserver {
RecyclerViewDataObserver() {
}
@Override
public void onItemRangeChanged(int positionStart, int itemCount, Object payload) {
assertNotInLayoutOrScroll(null);
if (mAdapterHelper.onItemRangeChanged(positionStart, itemCount, payload)) {
triggerUpdateProcessor();
}
}
@Override
public void onItemRangeInserted(int positionStart, int itemCount) {
assertNotInLayoutOrScroll(null);
if (mAdapterHelper.onItemRangeInserted(positionStart, itemCount)) {
triggerUpdateProcessor();
}
}
@Override
public void onItemRangeRemoved(int positionStart, int itemCount) {
assertNotInLayoutOrScroll(null);
if (mAdapterHelper.onItemRangeRemoved(positionStart, itemCount)) {
triggerUpdateProcessor();
}
}
}
void assertNotInLayoutOrScroll(String message) {
if (isComputingLayout()) {
if (message == null) {
throw new IllegalStateException("Cannot call this method while RecyclerView is "
+ "computing a layout or scrolling" + exceptionLabel());
}
throw new IllegalStateException(message);
}
}
public boolean isComputingLayout() {
return mLayoutOrScrollCounter > 0;
}
2、产生原因
为什么mLayoutOrScrollCounter > 0
2.1、recyclerView的onLayout
protected void onLayout(boolean changed, int l, int t, int r, int b) {
dispatchLayout();
}
void dispatchLayout() {
mState.mIsMeasuring = false;
if (mState.mLayoutStep == State.STEP_START) {
dispatchLayoutStep1();
mLayout.setExactMeasureSpecsFrom(this);
dispatchLayoutStep2();
} else if (mAdapterHelper.hasUpdates() || mLayout.getWidth() != getWidth()
|| mLayout.getHeight() != getHeight()) {
dispatchLayoutStep2();
} else {
mLayout.setExactMeasureSpecsFrom(this);
}
dispatchLayoutStep3();
}
2.2、看下 dispatchLayoutStep1/2
private void dispatchLayoutStep 1/2 () {
onEnterLayoutOrScroll();
mLayout.onLayoutChildren(mRecycler, mState);
onExitLayoutOrScroll();
}
void onEnterLayoutOrScroll() {
mLayoutOrScrollCounter++;
}
void onExitLayoutOrScroll(boolean enableChangeEvents) {
mLayoutOrScrollCounter--;
}
从上面看出每次执行 dispatchLayoutStep1/2开始mLayoutOrScrollCounter++，执行完成mLayoutOrScrollCounter--就等于0，期间执行 mLayout.onLayoutChildren()操作。如果onLayoutChildren出现异常，则mLayoutOrScrollCounter就会大于0。
而java.lang.IllegalArgumentException就是在mLayout.onLayoutChildren方法执行过程中调用的，所以由于第一个异常未处理，产生了第二个异常，实际不可能同时出现两个crash异常。
原因 ： 自定义的HyLinearLayoutManager被try——catch，导致第一个异常没有导致app闪退，当再次执行onItemRangeRemoved时，产生了第二个异常。所以只需要找到第一个问题的原因则可。
// HyLinearLayoutManager
@Override
public void onLayoutChildren(RecyclerView.Recycler recycler, RecyclerView.State state) {
try {
//try catch一下
super.onLayoutChildren(recycler, state);
} catch (Exception e) {
e.printStackTrace();
}
}
3、分析mLayout.onLayoutChildren(mRecycler, mState);
以dispatchLayoutStep2中onLayoutChildren方法为例介绍。
recyclerview缓存
3.1、 notifyItemRemove(7)
正常情况下，是不会出现crash，下面是写demo可以验证。
btn1.setOnClickListener {
var stringList = (recyclerView.adapter as ItemAdapter).stringList as LinkedList
stringList.removeAt(1)
(recyclerView?.adapter as ItemAdapter).notifyItemRemoved(2)
Log.d(TAG, "onCreate:--after-- " + recyclerView.isComputingLayout)
}
btn2.setOnClickListener {
adapter.notifyDataSetChanged()
}
当调用notifyItemRemove(7)时，dispatchLayoutStep2会从mAttachedScrap加载混存的holder。
3.11、寻找到第0个，加入RecyclerView第0个。
3.12、寻找到第1个，加入RecyclerView第1个。
3.13、寻找到第2个，加入RecyclerView第2个。
3.14、寻找到第3个,此时第三个item的type和mAdapter返回的type不一致。所以找不到，会依据type创建一个holder。
//getScrapOrHiddenOrCachedHolderForPosition
for (int i = 0; i < scrapCount; i++) {
final ViewHolder holder = mAttachedScrap.get(i);
if (!holder.wasReturnedFromScrap() && holder.getLayoutPosition() == position
&& !holder.isInvalid() && (mState.mInPreLayout || !holder.isRemoved())) {
holder.addFlags(ViewHolder.FLAG_RETURNED_FROM_SCRAP);
return holder;
}
}
//创建
holder = mAdapter.createViewHolder(RecyclerView.this, type);
此时按照type，倒数第二个type为Item_Type_load，会返回一个holder，这个holder的itemview为mLoadView。加入RecyclerView为第三个holder。
@Override
public int getItemViewType(int position) {
if (isLoadPosition(position)) {
return ITEM_TYPE_LOAD;
} else if (isBottomPosition(position)) {
return ITEM_TYPE_BOTTOM;
}
return super.getItemViewType(position);
}
此时mAttachedScrap中有一个持有mLoadView的ViewHolder，RecyclerView中也加入了一个持有LoadView的ViewHolder。
3.15、寻找第4个，此时找到的事mLoadView的holder，但是这个holder的type和mAdapter返回type不一致，此时需要把holder移除。出现如下crash。因为刚才我们已经加入到recyclerView,移除报错。
protected void removeDetachedView(View child, boolean animate) {
ViewHolder vh = getChildViewHolderInt(child);
if (vh != null) {
if (vh.isTmpDetached()) {
vh.clearTmpDetachFlag();
} else if (!vh.shouldIgnore()) {
throw new IllegalArgumentException("Called removeDetachedView with a view which"
+ " is not flagged as tmp detached." + vh + exceptionLabel());
}
}
}
3.2、notifyItemRemove(3)
删除3，但是我们通知3时，当notifyItemRemove(3)。
缓存
3.21、寻找到第0个，加入RecyclerView第0个。
3.22、寻找到第1个，加入RecyclerView第1个。
3.23、寻找到第2个，加入RecyclerView第2个。
3.24、寻找到第3个，此时mAttachedScrap中有个2个位置为3个holder，一个是移除holder，一个mLoadView（位置已经做了正确的偏移），找到了holder。
3.25、寻找到第4个，也找到已经偏移位置的line。加入到RecyclerView中，不会出现任何问题。
3.3、notifyItemRemove(4)
3.3.1、寻找到第0个，加入RecyclerView第0个。
3.3.2、寻找到第1个，加入RecyclerView第1个。
3.3.3、寻找到第2个，加入RecyclerView第2个。
3.3.4、寻找到第3个，此时mAttachedScrap中找到的holder的type和mAdapter需要的type不一致，所以会创建一个holder加入进去。我们上面知道加入的事mLoadView。
此时mAttachedScrap和RecyclerView中各有一个持有同一个mLoadView的ViewHolder。
3.3.5、寻找到第4个，也找到已经偏移位置的line。加入到RecyclerView中，不会出现任何问题。因为在这个位置找到了holder，不需要移除持有mLoadView的viewHolder，所以不会报第一个中的异常。
3.3.6、执行动画。
动画
对于loadViewHolder执行消失动画。
void animateDisappearance(@NonNull ViewHolder holder,
@NonNull ItemHolderInfo preLayoutInfo, @Nullable ItemHolderInfo postLayoutInfo) {
addAnimatingView(holder);
holder.setIsRecyclable(false);
if (mItemAnimator.animateDisappearance(holder, preLayoutInfo, postLayoutInfo)) {
postAnimationRunner();
}
}
private void addAnimatingView(ViewHolder viewHolder) {
final View view = viewHolder.itemView;
final boolean alreadyParented = view.getParent() == this;
mRecycler.unscrapView(getChildViewHolder(view));
if (viewHolder.isTmpDetached()) {
// re-attach
mChildHelper.attachViewToParent(view, -1, view.getLayoutParams(), true);
} else if (!alreadyParented) {
mChildHelper.addView(view, true);
} else {
mChildHelper.hide(view);
}
}
mChildHelper.attachViewToParent就抛出了crash。因为loadViewHolder所持有的ItemView已经被加入到了RecyclerView。
4、解决方案
私信
public void removeData(String msgId) {
int index = -1;
for (Iterator iterable = getDatas().iterator(); iterable.hasNext(); ) {
ChatMsgBean chatMsgBaseBean = (ChatMsgBean) iterable.next();
index++;
if (!TextUtils.isEmpty(msgId) && msgId.equals(chatMsgBaseBean.msgId)) {
try {
iterable.remove();
notifyItemRemoved(index);
if (index > 0) {
notifyItemChanged(index - 1);
}
} catch (Exception e) {
e.printStackTrace();
}
}
}
}
上述代码执行
notifyItemRemoved(0) 执行完只剩1条数据。
notifyItemRemoved(1);
当执行notifyItemRemoved(1)时，此时list只有一条数据，就会导致上面notifyItemRemoved(4)的场景。
这里只列举删除，当然增删改查都可能导致这个问题。
public void removeData(String msgId) {
int index = -1;
List<ChatMsgBean> datas = getDatas();
for (int i = 0; i < datas.size(); i++) {
ChatMsgBean chatMsgBean = datas.get(i);
if (!TextUtils.isEmpty(msgId) && msgId.equals(chatMsgBean.msgId)) {
index = i;
break;
}
}
if (index != -1) {
datas.remove(index);
notifyItemRemoved(index);
}
}
4.1、避免每次创建的viewholder和缓存中的ViewHolder持有同一个View.
//PullToLoadAdapter
@Override
public RecyclerView.ViewHolder onCreateViewHolder(ViewGroup parent, int viewType) {
if (viewType == ITEM_TYPE_LOAD) {
mRealLoadView = createWrapView(mLoadView);
return new RecyclerView.ViewHolder(mRealLoadView) {
};
} else if (viewType == ITEM_TYPE_BOTTOM) {
mRealBottomView = createWrapView(mBottomView);
return new RecyclerView.ViewHolder(mRealBottomView) {
};
}
return super.onCreateViewHolder(parent, viewType);
}
// HeaderAndFooterAdapter
@Override
public RecyclerView.ViewHolder onCreateViewHolder(ViewGroup parent, int viewType) {
// 如果是头部
if (isHeaderType(viewType)) {
int headerPosition = mHeaderViews.indexOfKey(viewType);
View headerView = mHeaderViews.valueAt(headerPosition);
// if (mOnCreateHeaderViewHolderListener != null && headerView != null
// && headerView.getTag() != null && headerView.getTag() instanceof Integer) {
// if ((int) headerView.getTag() > 0) {
// return mOnCreateHeaderViewHolderListener.onCreateHeaderViewHolder(parent, viewType, (int) headerView
// .getTag());
// }
// }
return createHeaderAndFooterViewHolder(createWrapView(headerView));
}
// 如果是placeHolder
if (isPlaceHolderType(viewType)) {
View view = LayoutInflater.from(mContext.getApplicationContext()).inflate(R.layout.placeholer_recyclerview, null,
false);
return new HyPlaceHolderView(view);
}
// 如果是尾部
if (isFooterType(viewType)) {
int footerPosition = mFooterViews.indexOfKey(viewType);
View footerView = mFooterViews.valueAt(footerPosition);
return createHeaderAndFooterViewHolder(createWrapView(footerView));
}
return mRealAdapter.onCreateViewHolder(parent, viewType);
}
protected FrameLayout createWrapView(View view) {
FrameLayout frameLayout = new FrameLayout(mContext);
ViewParent parent = view.getParent();
LogUtil.d("HyRecyclerView",
"onCreateViewHolder_0: " + parent + " " + view.getTag() + " params.h =" + view.getLayoutParams() + " " +
"visiable= " + view.getVisibility());
if (parent != null && parent instanceof ViewGroup) {
ViewGroup viewGroup = (ViewGroup) parent;
viewGroup.removeView(view);
}
frameLayout.setVisibility(view.getVisibility());
if (view.getLayoutParams() != null) {
ViewGroup.LayoutParams frlayoutParams = new ViewGroup.LayoutParams(ViewGroup.LayoutParams.MATCH_PARENT,
view.getLayoutParams().height);
frameLayout.setLayoutParams(frlayoutParams);
} else {
ViewGroup.LayoutParams frlayoutParams = new ViewGroup.LayoutParams(ViewGroup.LayoutParams.MATCH_PARENT,
ViewGroup.LayoutParams.WRAP_CONTENT);
frameLayout.setLayoutParams(frlayoutParams);
}
frameLayout.addView(view);
return frameLayout;
}
因为topView和mRefreshView用于刷新，bottomView和loadView用于加载，因此
添加了一层，在PullToRefreshRecyclerView和HyRecyclerView里面都需要替换控件，并且将bottomView等属性赋值包裹的View。
4.2、从上面可知，因为在对应position没有获取到holder，所以新创建了一个。想办法从mAttachscrap中获取缓存。
ViewHolder tryGetViewHolderForPositionByDeadline(int position,
boolean dryRun, long deadlineNs) {
boolean fromScrapOrHiddenOrCache = false;
ViewHolder holder = null;
// 0) If there is a changed scrap, try to find from there
if (mState.isPreLayout()) {
holder = getChangedScrapViewForPosition(position);
fromScrapOrHiddenOrCache = holder != null;
}
// 1) Find by position from scrap/hidden list/cache
if (holder == null) {
holder = getScrapOrHiddenOrCachedHolderForPosition(position, dryRun);
if (holder != null) {
if (!validateViewHolderForOffsetPosition(holder)) {
// recycle holder (and unscrap if relevant) since it can't be used
if (!dryRun) {
// we would like to recycle this but need to make sure it is not used by
// animation logic etc.
holder.addFlags(ViewHolder.FLAG_INVALID);
if (holder.isScrap()) {
removeDetachedView(holder.itemView, false);
holder.unScrap();
} else if (holder.wasReturnedFromScrap()) {
holder.clearReturnedFromScrapFlag();
}
recycleViewHolderInternal(holder);
}
holder = null;
} else {
fromScrapOrHiddenOrCache = true;
}
}
}
if (holder == null) {
final int offsetPosition = mAdapterHelper.findPositionOffset(position);
if (offsetPosition < 0 || offsetPosition >= mAdapter.getItemCount()) {
throw new IndexOutOfBoundsException("Inconsistency detected. Invalid item "
+ "position " + position + "(offset:" + offsetPosition + ")."
+ "state:" + mState.getItemCount() + exceptionLabel());
}
final int type = mAdapter.getItemViewType(offsetPosition);
// 2) Find from scrap/cache via stable ids, if exists
if (mAdapter.hasStableIds()) {
holder = getScrapOrCachedViewForId(mAdapter.getItemId(offsetPosition),
type, dryRun);
if (holder != null) {
// update position
holder.mPosition = offsetPosition;
fromScrapOrHiddenOrCache = true;
}
}
}
处理给adapter的item设置唯一的ID，重写geiItemID方法。
mAdapter.setHasStableIds(true);
@Override
public long getItemId(int position) {
return super.getItemId(position);
}
总结
添加header和footer时，由于缓存复用，避免创建的Viewholder持有同一个View。
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