Crash on data-set update when DiffUtils is used

• I have searched existing issues and confirmed this is not a duplicate

Issues and steps to reproduce

I’m seeing this crash when trying to filter my list items using a search query:

FATAL EXCEPTION: main
java.lang.ArrayIndexOutOfBoundsException: length=45; index=-1
    at com.google.android.flexbox.FlexboxLayoutManager$AnchorInfo.assignFromView(FlexboxLayoutManager.java:2863)
    at com.google.android.flexbox.FlexboxLayoutManager$AnchorInfo.access$1900(FlexboxLayoutManager.java:2792)
    at com.google.android.flexbox.FlexboxLayoutManager.updateAnchorFromChildren(FlexboxLayoutManager.java:1136)
    at com.google.android.flexbox.FlexboxLayoutManager.updateAnchorInfoForLayout(FlexboxLayoutManager.java:1032)
    at com.google.android.flexbox.FlexboxLayoutManager.onLayoutChildren(FlexboxLayoutManager.java:700)
    at android.support.v7.widget.RecyclerView.dispatchLayoutStep2(RecyclerView.java:3583)
    at android.support.v7.widget.RecyclerView.dispatchLayout(RecyclerView.java:3312)
    at android.support.v7.widget.RecyclerView.onLayout(RecyclerView.java:3844)

Steps to reproduce This started to happen after I added DiffUtils for showing item animations. Here’s what I’m doing:

List<FolderSubscription> oldSubscriptions = ...;
List<FolderSubscription> newSubscriptions = ...;

FolderSubscriptionDiffCallbacks callback = new FolderSubscriptionDiffCallbacks(oldSubscriptions, newSubscriptions);
DiffUtil.DiffResult folderDiffResult = DiffUtil.calculateDiff(callback, true /* detectMoves */);

folderAdapter.updateData(newSubscriptions);
folderDiffResult.dispatchUpdatesTo(folderAdapter);

Version of the flexbox library

I tested on both v0.3-alpha3 and v0.3.

[shrpereira]

I’m having the same issue using Renderers library and their diff algorithm with FlexboxLayoutManager. The lib algorithm is the following:

  DiffCallback diffCallback = new DiffCallback(collection, newList);
  DiffUtil.DiffResult diffResult = DiffUtil.calculateDiff(diffCallback);
  clear();
  addAll(newList);
  diffResult.dispatchUpdatesTo(this);

Changing from their adapter.diffUpdate(list) to the conventional updating the list and calling adapter.notifyDataSetChanged(); works but I’ve lost the animation.

[j-garin]

@thagikura still getting this FC

Issues and steps to reproduce

Update the items in androidx.recyclerview.widget.RecyclerView with androidx.recyclerview.widget.ListAdapter

Expected behavior

The list should handle multiple changes

Version of the flexbox library

1.1.0

Link to code

		val layoutManager = FlexboxLayoutManager(recyclerView.context)
				.apply {
					flexWrap = FlexWrap.WRAP
					flexDirection = FlexDirection.ROW
					justifyContent = JustifyContent.CENTER
					alignItems = AlignItems.CENTER
				}
		recyclerView.layoutManager = layoutManager
		recyclerView.adapter = adapter

happens when adapter.submitList(newList) gets called often. I have about 10 items in the list in my case, 1 item gets changed per call.

java.lang.IllegalStateException: The specified child already has a parent. You must call removeView() on the child's parent first.
        at android.view.ViewGroup.addViewInner(ViewGroup.java:4941)
        at android.view.ViewGroup.addView(ViewGroup.java:4772)
        at android.view.ViewGroup.addView(ViewGroup.java:4712)
        at androidx.recyclerview.widget.RecyclerView$5.addView(RecyclerView.java:851)
        at androidx.recyclerview.widget.ChildHelper.addView(ChildHelper.java:107)
        at androidx.recyclerview.widget.RecyclerView$LayoutManager.addViewInt(RecyclerView.java:8336)
        at androidx.recyclerview.widget.RecyclerView$LayoutManager.addView(RecyclerView.java:8294)
        at androidx.recyclerview.widget.RecyclerView$LayoutManager.addView(RecyclerView.java:8282)
        at com.google.android.flexbox.FlexboxLayoutManager.layoutFlexLineMainAxisHorizontal(FlexboxLayoutManager.java:1513)
        at com.google.android.flexbox.FlexboxLayoutManager.layoutFlexLine(FlexboxLayoutManager.java:1434)
        at com.google.android.flexbox.FlexboxLayoutManager.fill(FlexboxLayoutManager.java:1286)
        at com.google.android.flexbox.FlexboxLayoutManager.onLayoutChildren(FlexboxLayoutManager.java:754)
        at androidx.recyclerview.widget.RecyclerView.dispatchLayoutStep2(RecyclerView.java:3924)
        at androidx.recyclerview.widget.RecyclerView.dispatchLayout(RecyclerView.java:3641)