RecyclerView.Adapter.notifyItemChanged() 从不将负载传递给 onBindViewHolder()

Question

我正在尝试更新 RecyclerView 中的 ViewHolder 而不重新绑定整个内容。根据文档，我应该通过调用 RecyclerView.Adapter.notifyItemChanged(int position, Object payload) 来完成此操作，其中 payload 是将传递给 RecyclerView.Adapter.onBindViewHolder(VH holder, int position, List<Object> payloads) 的任意对象，我将能够在其中更新 ViewHolder。

但是当我尝试这样做时，onBindViewHolder 总是收到一个空列表。在这两个调用之间，有效负载的内部列表被清除。在RecyclerView的源代码处设置断点后，由于relayout，最终调用了RecyclerView.ViewHolder.clearPayload()

有没有其他人设法让这个工作？这是支持库中的错误还是我已经触发了这两个函数之间的重新布局？

这是清除有效负载时的堆栈跟踪：

"<1> main@831692616832" prio=5 runnable
  java.lang.Thread.State: RUNNABLE
      at android.support.v7.widget.RecyclerView$ViewHolder.clearPayload(RecyclerView.java:8524)
      at android.support.v7.widget.RecyclerView$ViewHolder.resetInternal(RecyclerView.java:8553)
      at android.support.v7.widget.RecyclerView$Recycler.getViewForPosition(RecyclerView.java:4544)
      at android.support.v7.widget.RecyclerView$Recycler.getViewForPosition(RecyclerView.java:4461)
      at android.support.v7.widget.LayoutState.next(LayoutState.java:86)
      at android.support.v7.widget.StaggeredGridLayoutManager.fill(StaggeredGridLayoutManager.java:1423)
      at android.support.v7.widget.StaggeredGridLayoutManager.onLayoutChildren(StaggeredGridLayoutManager.java:610)
      at android.support.v7.widget.RecyclerView.dispatchLayout(RecyclerView.java:2847)
      at android.support.v7.widget.RecyclerView.onLayout(RecyclerView.java:3145)
      at android.view.View.layout(View.java:14289)
      at android.view.ViewGroup.layout(ViewGroup.java:4562)
      at android.support.v4.widget.SwipeRefreshLayout.onLayout(SwipeRefreshLayout.java:581)
      at android.view.View.layout(View.java:14289)
      at android.view.ViewGroup.layout(ViewGroup.java:4562)
      at android.widget.FrameLayout.onLayout(FrameLayout.java:448)
      at android.view.View.layout(View.java:14289)
      at android.view.ViewGroup.layout(ViewGroup.java:4562)
      at android.widget.FrameLayout.onLayout(FrameLayout.java:448)
      at android.view.View.layout(View.java:14289)
      at android.view.ViewGroup.layout(ViewGroup.java:4562)
      at android.widget.FrameLayout.onLayout(FrameLayout.java:448)
      at android.view.View.layout(View.java:14289)
      at android.view.ViewGroup.layout(ViewGroup.java:4562)
      at android.widget.FrameLayout.onLayout(FrameLayout.java:448)
      at android.view.View.layout(View.java:14289)
      at android.view.ViewGroup.layout(ViewGroup.java:4562)
      at android.widget.LinearLayout.setChildFrame(LinearLayout.java:1671)
      at android.widget.LinearLayout.layoutVertical(LinearLayout.java:1525)
      at android.widget.LinearLayout.onLayout(LinearLayout.java:1434)
      at android.view.View.layout(View.java:14289)
      at android.view.ViewGroup.layout(ViewGroup.java:4562)
      at android.support.v4.widget.DrawerLayout.onLayout(DrawerLayout.java:1043)
      at android.view.View.layout(View.java:14289)
      at android.view.ViewGroup.layout(ViewGroup.java:4562)
      at android.widget.FrameLayout.onLayout(FrameLayout.java:448)
      at android.view.View.layout(View.java:14289)
      at android.view.ViewGroup.layout(ViewGroup.java:4562)
      at android.widget.LinearLayout.setChildFrame(LinearLayout.java:1671)
      at android.widget.LinearLayout.layoutVertical(LinearLayout.java:1525)
      at android.widget.LinearLayout.onLayout(LinearLayout.java:1434)
      at android.view.View.layout(View.java:14289)
      at android.view.ViewGroup.layout(ViewGroup.java:4562)
      at android.widget.FrameLayout.onLayout(FrameLayout.java:448)
      at android.view.View.layout(View.java:14289)
      at android.view.ViewGroup.layout(ViewGroup.java:4562)
      at android.widget.LinearLayout.setChildFrame(LinearLayout.java:1671)
      at android.widget.LinearLayout.layoutVertical(LinearLayout.java:1525)
      at android.widget.LinearLayout.onLayout(LinearLayout.java:1434)
      at android.view.View.layout(View.java:14289)
      at android.view.ViewGroup.layout(ViewGroup.java:4562)
      at android.widget.FrameLayout.onLayout(FrameLayout.java:448)
      at android.view.View.layout(View.java:14289)
      at android.view.ViewGroup.layout(ViewGroup.java:4562)
      at android.view.ViewRootImpl.performLayout(ViewRootImpl.java:1976)
      at android.view.ViewRootImpl.performTraversals(ViewRootImpl.java:1730)
      at android.view.ViewRootImpl.doTraversal(ViewRootImpl.java:1004)
      at android.view.ViewRootImpl$TraversalRunnable.run(ViewRootImpl.java:5481)
      at android.view.Choreographer$CallbackRecord.run(Choreographer.java:749)
      at android.view.Choreographer.doCallbacks(Choreographer.java:562)
      at android.view.Choreographer.doFrame(Choreographer.java:532)
      at android.view.Choreographer$FrameDisplayEventReceiver.run(Choreographer.java:735)
      at android.os.Handler.handleCallback(Handler.java:730)
      at android.os.Handler.dispatchMessage(Handler.java:92)
      at android.os.Looper.loop(Looper.java:137)
      at android.app.ActivityThread.main(ActivityThread.java:5103)
      at java.lang.reflect.Method.invokeNative(Method.java:-1)
      at java.lang.reflect.Method.invoke(Method.java:525)
      at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:737)
      at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:553)
      at dalvik.system.NativeStart.main(NativeStart.java:-1)

Answer 1

为什么不简单地使用 RecyclerView.Adapter.notifyItemChanged(int position) 文档在提到

时似乎有点模棱两可

  RecyclerView.Adapter.notifyItemChanged(int position,Object payload)

Client can optionally pass a payload for partial change. These payloads will be merged and may be passed to adapter's onBindViewHolder(ViewHolder, int, List)

因此不能保证您会在 onBindViewHolder 中收到列表

Answer 2

RecyclerView 默认为 creates another copy 的 ViewHolder，以便使视图相互淡入淡出。这导致了问题，因为旧的 ViewHolder 获得了有效载荷，但新的没有。所以你需要明确地告诉它重用旧的：

DefaultItemAnimator animator = new DefaultItemAnimator() {
        @Override
        public boolean canReuseUpdatedViewHolder(RecyclerView.ViewHolder viewHolder) {
            return true;
        }
    };
mRecyclerView.setItemAnimator(animator);

Answer 3

如果您使用项目动画器（默认情况下启用），则负载将始终为空。看看this answer in android issue tracker:

This is how payload is designed the work. It is only passed to on bind "if we are rebinding to the same view holder". Same for data binding, if you are not binding to the same view holder, you cannot do the bind incrementally. In case of change animations, RV creates two copies of the View to crossfade so you are not binding to the same VH in postLayout.

Soon, we'll provide an API to run change animations within the same ViewHolder.

因此，在他们分享这个新的 API 之前，我们需要使用这样的东西：

mRecyclerView.setItemAnimator(null);

编辑：请参阅@blindOSX 评论，他注意到要启用有效载荷，您只能禁用项目更改事件的动画。

编辑2：看起来他们已经在没有通知的情况下更新了这种行为。查看更新后的 .

Answer 4

在某些情况下，它适用于 notifyItemRangeChanged(getItemRealCount(), 1)。

RecyclerView.Adapter.notifyItemChanged() 从不将负载传递给 onBindViewHolder()

RecyclerView.Adapter.notifyItemChanged() never passes payload to onBindViewHolder()

android

android-adapter

android-support-library

android-recyclerview