Null pointer exception with recyclerview

I’m wrapping BottomSheetLayout around a LinearLayout that contains a RecyclerView (which is populated with RelativeLayouts). To test it, I’m calling

BottomSheetLayout bottomSheet = (BottomSheetLayout) v.findViewById(R.id.bottomsheet);
    bottomSheet.showWithSheetView(inflater.inflate(R.layout.fragment_layout, bottomSheet, false));

at the end of the fragment’s onCreateView(), after the recyclerview has already been set up.

However, this ends up breaking the RecyclerView, as any touch input causes this stack trace:

java.lang.NullPointerException: Attempt to invoke virtual method 'boolean android.support.v7.widget.RecyclerView$LayoutManager.canScrollVertically()' on a null object reference
        at android.support.v7.widget.RecyclerView.computeVerticalScrollOffset(RecyclerView.java:1540)
        at android.view.View.canScrollVertically(View.java:12835)
        at android.support.v4.view.ViewCompatICS.canScrollVertically(ViewCompatICS.java:35)
        at android.support.v4.view.ViewCompat$ICSViewCompatImpl.canScrollVertically(ViewCompat.java:1161)
        at android.support.v4.view.ViewCompat.canScrollVertically(ViewCompat.java:1575)
        at android.support.v4.widget.SwipeRefreshLayout.canChildScrollUp(SwipeRefreshLayout.java:643)
        at android.support.v4.widget.SwipeRefreshLayout.onInterceptTouchEvent(SwipeRefreshLayout.java:657)
        at android.view.ViewGroup.dispatchTouchEvent(ViewGroup.java:1960)
        at android.view.ViewGroup.dispatchTransformedTouchEvent(ViewGroup.java:2405)
        at android.view.ViewGroup.dispatchTouchEvent(ViewGroup.java:2049)
        at android.view.ViewGroup.dispatchTransformedTouchEvent(ViewGroup.java:2405)
        at android.view.ViewGroup.dispatchTouchEvent(ViewGroup.java:2049)
        at android.view.ViewGroup.dispatchTransformedTouchEvent(ViewGroup.java:2405)
        at android.view.ViewGroup.dispatchTouchEvent(ViewGroup.java:2049)
        at android.view.ViewGroup.dispatchTransformedTouchEvent(ViewGroup.java:2405)
        at android.view.ViewGroup.dispatchTouchEvent(ViewGroup.java:2049)
        at android.view.ViewGroup.dispatchTransformedTouchEvent(ViewGroup.java:2405)
        at android.view.ViewGroup.dispatchTouchEvent(ViewGroup.java:2049)
        at android.view.ViewGroup.dispatchTransformedTouchEvent(ViewGroup.java:2405)
        at android.view.ViewGroup.dispatchTouchEvent(ViewGroup.java:2049)
        at android.view.ViewGroup.dispatchTransformedTouchEvent(ViewGroup.java:2405)
        at android.view.ViewGroup.dispatchTouchEvent(ViewGroup.java:2049)
        at android.view.ViewGroup.dispatchTransformedTouchEvent(ViewGroup.java:2405)
        at android.view.ViewGroup.dispatchTouchEvent(ViewGroup.java:2049)
        at android.view.ViewGroup.dispatchTransformedTouchEvent(ViewGroup.java:2405)
        at android.view.ViewGroup.dispatchTouchEvent(ViewGroup.java:2049)
        at android.view.ViewGroup.dispatchTransformedTouchEvent(ViewGroup.java:2405)
        at android.view.ViewGroup.dispatchTouchEvent(ViewGroup.java:2049)
        at android.view.ViewGroup.dispatchTransformedTouchEvent(ViewGroup.java:2405)
        at android.view.ViewGroup.dispatchTouchEvent(ViewGroup.java:2049)
        at android.view.ViewGroup.dispatchTransformedTouchEvent(ViewGroup.java:2405)
        at android.view.ViewGroup.dispatchTouchEvent(ViewGroup.java:2049)
        at android.view.ViewGroup.dispatchTransformedTouchEvent(ViewGroup.java:2405)
        at android.view.ViewGroup.dispatchTouchEvent(ViewGroup.java:2049)
        at android.view.ViewGroup.dispatchTransformedTouchEvent(ViewGroup.java:2405)
        at android.view.ViewGroup.dispatchTouchEvent(ViewGroup.java:2049)
        at com.android.internal.policy.impl.PhoneWindow$DecorView.superDispatchTouchEvent(PhoneWindow.java:2369)
        at com.android.internal.policy.impl.PhoneWindow.superDispatchTouchEvent(PhoneWindow.java:1719)
        at android.app.Activity.dispatchTouchEvent(Activity.java:2742)
        at android.support.v7.internal.view.WindowCallbackWrapper.dispatchTouchEvent(WindowCallbackWrapper.java:60)
        at android.support.v7.internal.view.WindowCallbackWrapper.dispatchTouchEvent(WindowCallbackWrapper.java:60)
        at com.android.internal.policy.impl.PhoneWindow$DecorView.dispatchTouchEvent(PhoneWindow.java:2330)
        at android.view.View.dispatchPointerEvent(View.java:8666)
        at android.view.ViewRootImpl$ViewPostImeInputStage.processPointerEvent(ViewRootImpl.java:4123)
        at android.view.ViewRootImpl$ViewPostImeInputStage.onProcess(ViewRootImpl.java:3989)
        at android.view.ViewRootImpl$InputStage.deliver(ViewRootImpl.java:3544)
        at android.view.ViewRootImpl$InputStage.onDeliverToNext(ViewRootImpl.java:3597)
        at android.view.ViewRootImpl$InputStage.forward(ViewRootImpl.java:3563)
        at android.view.ViewRootImpl$AsyncInputStage.forward

Here’s a screenshot of what happens:

[ZacSweers]

I don’t think this is a bug on our end. I can’t say for sure from looking at your stacktrace what’s wrong with it (I’m able to use recyclerview in a sheet just fine on an internal project).

I would hazard a guess though that it has something to do with SwipeRefreshLayout, which would almost certainly not work as desired with bottom sheet. Not too familiar with its implementation under the hood, but I could imagine a case where it tries to get a view under a certain x/y position and (perhaps mistakenly) assumes that result is never null. Try removing that wrapper and see if that helps.

[yanbin92]

you use RecyclerView must use a LayoutManager, such as LinearLayoutManager layoutManager = new LinearLayoutManager(context); layoutManager.setOrientation(LinearLayoutManager.VERTICAL); mRecyclerView.setLayoutManager(layoutManager); i meet the same problem and solve the problem .