我有自定义纹理视图。我有一个循环器视图，循环器视图中的每个单元格都有我上面提到的纹理视图。我想要实现的是在纹理视图中播放视频。只有顶部可见纹理视图才能开始播放。但是，当第一个项完全不可见且我没有触摸显示时，我编写的代码会抛出空指针异常。我的代码如下所示：
mRecyclerView.setOnScrollListener(new RecyclerView.OnScrollListener() {
@Override
public void onScrollStateChanged(RecyclerView recyclerView, int newState) {
super.onScrollStateChanged(recyclerView, newState);
mPrevTopItemPos = mCurrentTopItemPos;
mCurrentTopItemPos = mLayoutManager.findFirstVisibleItemPosition();
if (newState == RecyclerView.SCROLL_STATE_IDLE) {
VSUtility.log("ScrollSTate:", "Idle");
ViewGroup parent = (ViewGroup) mRecyclerView.getChildAt(mCurrentTopItemPos);
FrameLayout videoFrame = (FrameLayout) parent.findViewById(R.id.surface_container);
if (videoFrame != null && VSUtility.isViewVisible(videoFrame, mRecyclerView)) {
VSUtility.displayToastMessage(getActivity(), "frame visible :" + mCurrentTopItemPos);
} else {
VSUtility.log("INVISIBLE:", "Idle" + mCurrentTopItemPos);
}
}
}
@Override
public void onScrolled(RecyclerView recyclerView, int dx, int dy) {
super.onScrolled(recyclerView, dx, dy);
paginateIfNecessary(recyclerView);
/*int itemAtTop = -1;
Rect visibleRect = new Rect();
itemAtTop = mLayoutManager.findFirstVisibleItemPosition();
mPrevItemInList = itemAtTop;
*//*VSCustomNearbyItemAdapter.ViewHolder holder = (VSCustomNearbyItemAdapter.ViewHolder)
mRecyclerView.getChildViewHolder(mRecyclerView.getChildAt(itemAtTop));*//*
FrameLayout frameLayout = (FrameLayout) mRecyclerView.getChildAt(itemAtTop)
.findViewById(R.id.surface_container);
//textureView.getWindowVisibleDisplayFrame(visibleRect);
if (isViewVisible(frameLayout)) {
if (mPrevItemInList > -1) {
}
SurfaceView sView = (SurfaceView) frameLayout.findViewById(R.id.surface_video_feeds);
ProgressBar progress = (ProgressBar) frameLayout.findViewById(R.id.progress_circular_video);
progress.setVisibility(View.VISIBLE);
VSUtility.log("Visiblity", "Visible");
} else {
VSUtility.log("Visiblity", "Invisible");
}*/
}
});
错误日志是：
java.lang.NullPointerException: Attempt to invoke virtual method 'android.view.View android.view.ViewGroup.findViewById(int)' on a null object reference
at fragments.VSNearbyFragment$1.onScrollStateChanged(VSNearbyFragment.java:184)
at android.support.v7.widget.RecyclerView.setScrollState(RecyclerView.java:823)
at android.support.v7.widget.RecyclerView.onTouchEvent(RecyclerView.java:1704)
at android.view.View.dispatchTouchEvent(View.java:8388)
at android.view.ViewGroup.dispatchTransformedTouchEvent(ViewGroup.java:2424)
at android.view.ViewGroup.dispatchTouchEvent(ViewGroup.java:2158)
at android.view.ViewGroup.dispatchTransformedTouchEvent(ViewGroup.java:2430)
at android.view.ViewGroup.dispatchTouchEvent(ViewGroup.java:2172)
at android.view.ViewGroup.dispatchTransformedTouchEvent(ViewGroup.java:2430)
at android.view.ViewGroup.dispatchTouchEvent(ViewGroup.java:2172)
at android.view.ViewGroup.dispatchTransformedTouchEvent(ViewGroup.java:2430)
at android.view.ViewGroup.dispatchTouchEvent(ViewGroup.java:2172)
at android.view.ViewGroup.dispatchTransformedTouchEvent(ViewGroup.java:2430)
at android.view.ViewGroup.dispatchTouchEvent(ViewGroup.java:2172)
at android.view.ViewGroup.dispatchTransformedTouchEvent(ViewGroup.java:2430)
at android.view.ViewGroup.dispatchTouchEvent(ViewGroup.java:2172)
at android.view.ViewGroup.dispatchTransformedTouchEvent(ViewGroup.java:2430)
at android.view.ViewGroup.dispatchTouchEvent(ViewGroup.java:2172)
at android.view.ViewGroup.dispatchTransformedTouchEvent(ViewGroup.java:2430)
at android.view.ViewGroup.dispatchTouchEvent(ViewGroup.java:2172)
at android.view.ViewGroup.dispatchTransformedTouchEvent(ViewGroup.java:2430)
at android.view.ViewGroup.dispatchTouchEvent(ViewGroup.java:2172)
at android.view.ViewGroup.dispatchTransformedTouchEvent(ViewGroup.java:2430)
at android.view.ViewGroup.dispatchTouchEvent(ViewGroup.java:2172)
at android.view.ViewGroup.dispatchTransformedTouchEvent(ViewGroup.java:2430)
at android.view.ViewGroup.dispatchTouchEvent(ViewGroup.java:2172)
at android.view.ViewGroup.dispatchTransformedTouchEvent(ViewGroup.java:2430)
at android.view.ViewGroup.dispatchTouchEvent(ViewGroup.java:2172)
at com.android.internal.policy.impl.PhoneWindow$DecorView.superDispatchTouchEvent(PhoneWindow.java:2314)
at com.android.internal.policy.impl.PhoneWindow.superDispatchTouchEvent(PhoneWindow.java:1692)
at android.app.Activity.dispatchTouchEvent(Activity.java:2739)
at com.android.internal.policy.impl.PhoneWindow$DecorView.dispatchTouchEvent(PhoneWindow.java:2275)
at android.view.View.dispatchPointerEvent(View.java:8578)
at android.view.ViewRootImpl$ViewPostImeInputStage.processPointerEvent(ViewRootImpl.java:4021)
at android.view.ViewRootImpl$ViewPostImeInputStage.onProcess(ViewRootImpl.java:3887)
at android.view.ViewRootImpl$InputStage.deliver(ViewRootImpl.java:3449)
at android.view.ViewRootImpl$InputStage.onDeliverToNext(ViewRootImpl.java:3502)
at android.view.ViewRootImpl$InputStage.forward(ViewRootImpl.java:3468)
at android.view.ViewRootImpl$AsyncInputStage.forward(ViewRootImpl.java:3578)
at android.view.ViewRootImpl$InputStage.apply(ViewRootImpl.java:3476)
at android.view.ViewRootImpl$AsyncInputStage.apply(ViewRootImpl.java:3635)
at android.view.ViewRootImpl$InputStage.deliver(ViewRootImpl.java:3449)
at android.view.ViewRootImpl$InputStage.onDeliverToNext(ViewRootImpl.java:3502)
at android.view.ViewRootImpl$InputStage.forward(ViewRootImpl.java:3468)
at android.view.ViewRootImpl$InputStage.apply(ViewRootImpl.java:3476)
at android.view.ViewRootImpl$InputStage.deliver(ViewRootImpl.java:3449)
at android.view.ViewRootImpl.deliverInputEvent(ViewRootImpl.java:5701)
at android.view.ViewRootImpl.doProcessInputEvents(ViewRootImpl.java:5675)
at android.view.ViewRootImpl.enqueueInputEvent(ViewRootImpl.java:5646)
at android.view.ViewRootImpl$WindowInputEventReceiver.onInputEvent(ViewRootImpl.java:5791)
at android.view.InputEventReceiver.dispatchInputEv
崩溃发生在以下行：
FrameLayout videoFrame = (FrameLayout) parent.findViewById(R.id.surface_container);
提前致谢。
答案 0 :(得分：0)
您应该使用的方法不是getChildAt。使用RecyclerView#findViewHolderForAdapterPosition。