android - RecyclerView.Adapter.notifyItemChanged() 永远不会将有效负载传递给 onBindViewHolder()

Question

我正在尝试更新 ViewHolder 中的 RecyclerView 而不重新绑定(bind)整个内容。根据文档，我应该通过调用 RecyclerView.Adapter.notifyItemChanged(int position, Object payload) 来做到这一点，其中 payload 是一个将传递给 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。

但是当我尝试这个时，onBindViewHolder 总是收到一个空列表。在这两个调用之间，内部负载列表被清除。在RecyclerView的源码设置断点后，由于relayout，最终调用了RecyclerView.ViewHolder.clearPayload()

还有其他人设法让它工作吗？这是支持库中的错误，还是我在这两个函数之间触发了重新布局？

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

RecyclerView 默认 creates another copy ViewHolder 以使 View 彼此淡入。这会导致问题，因为旧的 ViewHolder 获得了有效负载，但新的却没有。所以你需要明确告诉它重用旧的:

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