我已经搜索了FirebaseRecyclerAdapter和相关类的文档，但找不到一种方法来做我想做的事情（没有自己重建库）。
我正在开发一个内置消息传递的应用程序（包括组和其他用户的直接消息传递）。
群聊工作正常，因为它会从群聊节点下的数据库引用中提取每条消息。
直接消息很棘手。我想跳过引用中不包含当前用户的模型ID的节点，以及他们尝试发送消息的用户（以便他们看不到其他人的消息）。
在下面的代码中，如果viewType = 10，我试图返回null，因为我不希望显示的聊天气泡......正如您所期望的那样，我从RecyclerViewAdapter类中获得了一个空指针异常。 / p>
我知道为什么我收到错误。我故意将null传递给它，试图跳过（或迭代当前项），而不在任何位置显示聊天气泡。
这是我的firebase结构（导出的JSON）：Database Structure
这是一个堆栈跟踪供参考：
70这是我的FirebaseRecyclerAdapter：
FATAL EXCEPTION: main
Process: com.aztechdev.squad, PID: 21249
java.lang.NullPointerException: Attempt to write to field 'int android.support.v7.widget.RecyclerView$ViewHolder.mItemViewType' on a null object reference
at android.support.v7.widget.RecyclerView$Adapter.createViewHolder(RecyclerView.java:6368)
at android.support.v7.widget.RecyclerView$Recycler.tryGetViewHolderForPositionByDeadline(RecyclerView.java:5555)
at android.support.v7.widget.RecyclerView$Recycler.getViewForPosition(RecyclerView.java:5440)
at android.support.v7.widget.RecyclerView$Recycler.getViewForPosition(RecyclerView.java:5436)
at android.support.v7.widget.LinearLayoutManager$LayoutState.next(LinearLayoutManager.java:2224)
at android.support.v7.widget.LinearLayoutManager.layoutChunk(LinearLayoutManager.java:1551)
at android.support.v7.widget.LinearLayoutManager.fill(LinearLayoutManager.java:1511)
at android.support.v7.widget.LinearLayoutManager.onLayoutChildren(LinearLayoutManager.java:570)
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)
at android.view.View.layout(View.java:17637)
at android.view.ViewGroup.layout(ViewGroup.java:5575)
at android.widget.FrameLayout.layoutChildren(FrameLayout.java:323)
at android.widget.FrameLayout.onLayout(FrameLayout.java:261)
at android.view.View.layout(View.java:17637)
at android.view.ViewGroup.layout(ViewGroup.java:5575)
at android.widget.LinearLayout.setChildFrame(LinearLayout.java:1741)
at android.widget.LinearLayout.layoutVertical(LinearLayout.java:1585)
at android.widget.LinearLayout.onLayout(LinearLayout.java:1494)
at android.view.View.layout(View.java:17637)
at android.view.ViewGroup.layout(ViewGroup.java:5575)
at android.widget.FrameLayout.layoutChildren(FrameLayout.java:323)
at android.widget.FrameLayout.onLayout(FrameLayout.java:261)
at android.view.View.layout(View.java:17637)
at android.view.ViewGroup.layout(ViewGroup.java:5575)
at com.mxn.soul.flowingdrawer_core.FlowingDrawer.onLayout(FlowingDrawer.java:138)
at android.view.View.layout(View.java:17637)
at android.view.ViewGroup.layout(ViewGroup.java:5575)
at android.support.v4.view.ViewPager.onLayout(ViewPager.java:1795)
at android.view.View.layout(View.java:17637)
at android.view.ViewGroup.layout(ViewGroup.java:5575)
at android.support.constraint.ConstraintLayout.onLayout(ConstraintLayout.java:1197)
at android.view.View.layout(View.java:17637)
at android.view.ViewGroup.layout(ViewGroup.java:5575)
at android.support.design.widget.HeaderScrollingViewBehavior.layoutChild(HeaderScrollingViewBehavior.java:131)
at android.support.design.widget.ViewOffsetBehavior.onLayoutChild(ViewOffsetBehavior.java:42)
at android.support.design.widget.AppBarLayout$ScrollingViewBehavior.onLayoutChild(AppBarLayout.java:1391)
at android.support.design.widget.CoordinatorLayout.onLayout(CoordinatorLayout.java:870)
at android.view.View.layout(View.java:17637)
at android.view.ViewGroup.layout(ViewGroup.java:5575)
at android.support.v4.widget.DrawerLayout.onLayout(DrawerLayout.java:1193)
at android.view.View.layout(View.java:17637)
at android.view.ViewGroup.layout(ViewGroup.java:5575)
at android.widget.FrameLayout.layoutChildren(FrameLayout.java:323)
at android.widget.FrameLayout.onLayout(FrameLayout.java:261)
at android.view.View.layout(View.java:17637)
at android.view.ViewGroup.layout(ViewGroup.java:5575)
at android.widget.LinearLayout.setChildFrame(LinearLayout.java:1741)
at android.widget.LinearLayout.layoutVertical(LinearLayout.java:1585)
at android.widget.LinearLayout.onLayout(LinearLayout.java:1494)
at android.view.View.layout(View.java:17637)
at android.view.ViewGroup.layout(ViewGroup.java:5575)
at android.widget.FrameLayout.layoutChildren(FrameLayout.java:323)
at android.widget.FrameLayout.onLayout(FrameLayout.java:261)
09-02 10:47:22.899 21249-21249/com.aztechdev.squad E/AndroidRuntime: at android.view.View.layout(View.java:17637)
at android.view.ViewGroup.layout(ViewGroup.java:5575)
at android.widget.LinearLayout.setChildFrame(LinearLayout.java:1741)
at android.widget.LinearLayout.layoutVertical(LinearLayout.java:1585)
at android.widget.LinearLayout.onLayout(LinearLayout.java:1494)
at android.view.View.layout(View.java:17637)
at android.view.ViewGroup.layout(ViewGroup.java:5575)
at android.widget.FrameLayout.layoutChildren(FrameLayout.java:323)
at android.widget.FrameLayout.onLayout(FrameLayout.java:261)
at com.android.internal.policy.DecorView.onLayout(DecorView.java:726)
at android.view.View.layout(View.java:17637)
at android.view.ViewGroup.layout(ViewGroup.java:5575)
at android.view.ViewRootImpl.performLayout(ViewRootImpl.java:2346)
at android.view.ViewRootImpl.performTraversals(ViewRootImpl.java:2068)
at android.view.ViewRootImpl.doTraversal(ViewRootImpl.java:1254)
at android.view.ViewRootImpl$TraversalRunnable.run(ViewRootImpl.java:6337)
at android.view.Choreographer$CallbackRecord.run(Choreographer.java:874)
at android.view.Choreographer.doCallbacks(Choreographer.java:686)
at android.view.Choreographer.doFrame(Choreographer.java:621)
at android.view.Choreographer$FrameDisplayEventReceiver.run(Choreographer.java:860)
at android.os.Handler.handleCallback(Handler.java:751)
at android.os.Handler.dispatchMessage(Handler.java:95)
at android.os.Looper.loop(Looper.java:154)
at android.app.ActivityThread.main(ActivityThread.java:6119)
at java.lang.reflect.Method.invoke(Native Method)
at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:886)
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:776)
答案 0 :(得分：0)
您有三种选择：
更改数据结构，因此您无需跳过行。这是长期表现的最佳选择，但如果您只是试图通过POC，可能不是您的偏好。
不要使用FirebaseUI。使用基本Firebase库自行运行查询。然后在客户端上对结果进行后处理，以删除/省略您不想要的行。您必须将实际行计数返回到RecyclerView，而不包含您想要省略的那些行，并且只有您想要的行的干净数组是最简单的方法。
快速入侵：而不是返回null，而是返回0高度的视图！这是一个非常难看的黑客，但确实有效。