我在StackOverflow中已经多次看到这个问题，但是我无法解决此问题。所以伸出援助之手。请注意：我已经检查了其他有关SO的问题，尽管我可以摆脱该错误，但它还有其他问题。
这是我现有的代码：
我的适配器类：
public class RecyclerViewAdapter extends RecyclerView.Adapter<RecyclerView.ViewHolder> {
Context context;
private final int VIEW_TYPE_ITEM = 0;
private final int VIEW_TYPE_LOADING = 1;
private IOnLoadMoreListener mIOnLoadMoreListener;
private int visibleThreshold = 3;
private int lastVisibleItem, totalItemCount;
private int[] lastVisibleItems = new int[mStaggeredLayoutManager.getSpanCount()];
public RecyclerViewAdapter(Context context) {
this.context = context;
final StaggeredGridLayoutManager staggeredGridLayoutManager = (StaggeredGridLayoutManager) recyclerView.getLayoutManager();
recyclerView.addOnScrollListener(new RecyclerView.OnScrollListener() {
@Override
public void onScrolled(RecyclerView recyclerView, int dx, int dy) {
super.onScrolled(recyclerView, dx, dy);
totalItemCount = staggeredGridLayoutManager.getItemCount();
lastVisibleItems = staggeredGridLayoutManager.findLastVisibleItemPositions(new int[mStaggeredLayoutManager.getSpanCount()]);
if (staggeredGridLayoutManager.getSpanCount() == 1) {
lastVisibleItem = lastVisibleItems[0];
} else if (staggeredGridLayoutManager.getSpanCount() == 2) {
lastVisibleItem = Math.max(lastVisibleItems[0], lastVisibleItems[1]);
} else if (staggeredGridLayoutManager.getSpanCount() == 3) {
lastVisibleItem = Math.max(Math.max(lastVisibleItems[0], lastVisibleItems[1]), lastVisibleItems[2]);
}
if (!isRefreshing && totalItemCount <= lastVisibleItem + visibleThreshold) {
if (mIOnLoadMoreListener != null) {
mIOnLoadMoreListener.onLoadMore();
}
isRefreshing = true;
}
}
});
}
@Override
public RecyclerView.ViewHolder onCreateViewHolder(ViewGroup parent, int viewType) {
if (viewType == VIEW_TYPE_ITEM) {
View v = LayoutInflater.from(parent.getContext())
.inflate(R.layout.item_recyclerview_shop_fragment, parent, false);
return new CustomViewHolder(v);
} else if (viewType == VIEW_TYPE_LOADING) {
View v = LayoutInflater.from(parent.getContext())
.inflate(R.layout.item_recyclerview_loading_shop_fragment, parent, false);
return new LoadingViewHolder(v);
}
return null;
}
@Override
public void onBindViewHolder(RecyclerView.ViewHolder holder, int position) {
Product item = listItems.get(position);
if (holder.getItemViewType() == VIEW_TYPE_ITEM) {
CustomViewHolder customViewHolder = (CustomViewHolder) holder;
Glide.with(context).load(item.getFeaturedSrc()).into(customViewHolder.imageView);
} else if (holder.getItemViewType() == VIEW_TYPE_LOADING) {
if (holder instanceof LoadingViewHolder) {
LoadingViewHolder loadingViewHolder = (LoadingViewHolder) holder;
loadingViewHolder.progressBar.setIndeterminate(true);
}
}
}
@Override
public int getItemCount() {
return listItems == null ? 0 : listItems.size();
}
@Override
public int getItemViewType(int position) {
if (listItems.get(position) == null) {
return VIEW_TYPE_LOADING;
} else {
return VIEW_TYPE_ITEM;
}
}
public void setOnLoadMoreListener(IOnLoadMoreListener mIOnLoadMoreListener) {
this.mIOnLoadMoreListener = mIOnLoadMoreListener;
}
public class CustomViewHolder extends RecyclerView.ViewHolder implements View.OnClickListener {
ImageView imageView;
TextView textView;
String id;
public CustomViewHolder(View itemView) {
super(itemView);
itemView.setOnClickListener(this);
imageView = (ImageView) itemView.findViewById(R.id.imageView_thumbnail);
}
@Override
public void onClick(View v) {
int position = getAdapterPosition();
}
}
public class LoadingViewHolder extends RecyclerView.ViewHolder {
public ProgressBar progressBar;
public LoadingViewHolder(View progressView) {
super(progressView);
progressBar = (ProgressBar) progressView.findViewById(R.id.progressBar);
}
}
}
我以前的代码：
mRecyclerViewAdapter.setOnLoadMoreListener(new IOnLoadMoreListener() {
@Override
public void onLoadMore() {
listItems.add(null);
mRecyclerViewAdapter.notifyItemChanged(listItems.size() - 1);
mRecyclerViewAdapter.notifyDataSetChanged();
isProgressVisible = true;
getDataFromServer(false);
}
});
使用我的旧代码，我得到以下IllegalStateException：
W/RecyclerView: Cannot call this method in a scroll callback. Scroll callbacks mightbe run during a measure & layout pass where you cannot change theRecyclerView data. Any method call that might change the structureof the RecyclerView or the adapter contents should be postponed tothe next frame.
java.lang.IllegalStateException:
at android.support.v7.widget.RecyclerView.assertNotInLayoutOrScroll(RecyclerView.java:2581)
at android.support.v7.widget.RecyclerView$RecyclerViewDataObserver.onItemRangeChanged(RecyclerView.java:4943)
at android.support.v7.widget.RecyclerView$AdapterDataObservable.notifyItemRangeChanged(RecyclerView.java:11373)
at android.support.v7.widget.RecyclerView$AdapterDataObservable.notifyItemRangeChanged(RecyclerView.java:11364)
at android.support.v7.widget.RecyclerView$Adapter.notifyItemChanged(RecyclerView.java:6652)
at codsiga.com.xx.ShopFragment$1.onLoadMore(ShopFragment.java:148)
at codsiga.com.xx.ShopFragment$RecyclerViewAdapter$1.onScrolled(ShopFragment.java:229)
at android.support.v7.widget.RecyclerView.dispatchOnScrolled(RecyclerView.java:4618)
at android.support.v7.widget.RecyclerView.dispatchLayoutStep3(RecyclerView.java:3679)
at android.support.v7.widget.RecyclerView.dispatchLayout(RecyclerView.java:3323)
at android.support.v7.widget.RecyclerView.onLayout(RecyclerView.java:3844)
at android.view.View.layout(View.java:17637)
at android.view.ViewGroup.layout(ViewGroup.java:5575)
at android.widget.LinearLayout.setChildFrame(LinearLayout.java:1741)
at android.widget.LinearLayout.layoutVertical(LinearLayout.java:1585)
at android.widget.LinearLayout.onLayout(LinearLayout.java:1494)
at android.view.View.layout(View.java:17637)
at android.view.ViewGroup.layout(ViewGroup.java:5575)
at android.support.v4.widget.SwipeRefreshLayout.onLayout(SwipeRefreshLayout.java:636)
at android.view.View.layout(View.java:17637)
at android.view.ViewGroup.layout(ViewGroup.java:5575)
at android.widget.FrameLayout.layoutChildren(FrameLayout.java:323)
at android.widget.FrameLayout.onLayout(FrameLayout.java:261)
at android.view.View.layout(View.java:17637)
at android.view.ViewGroup.layout(ViewGroup.java:5575)
at android.support.v4.view.ViewPager.onLayout(ViewPager.java:1795)
at android.view.View.layout(View.java:17637)
at android.view.ViewGroup.layout(ViewGroup.java:5575)
at android.support.design.widget.HeaderScrollingViewBehavior.layoutChild(HeaderScrollingViewBehavior.java:131)
at android.support.design.widget.ViewOffsetBehavior.onLayoutChild(ViewOffsetBehavior.java:42)
at android.support.design.widget.AppBarLayout$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.widget.RelativeLayout.onLayout(RelativeLayout.java:1079)
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 android.widget.LinearLayout.setChildFrame(LinearLayout.java:1741)
at android.widget.LinearLayout.layoutVertical(LinearLayout.java:1585)
at android.widget.LinearLayout.onLayout(LinearLayout.java:1494)
03-22 11:36:32.083 3189-3189/codsiga.com.xx W/RecyclerView: 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)
因此，根据各种StackOverflow答案的建议，我如下修改了它：
修改后的代码着眼于各种答案：
mRecyclerViewAdapter.setOnLoadMoreListener(new IOnLoadMoreListener() {
@Override
public void onLoadMore() {
recyclerView.post(new Runnable() {
@Override
public void run() {
listItems.add(null);
mRecyclerViewAdapter.notifyItemChanged(listItems.size() - 1);
mRecyclerViewAdapter.notifyDataSetChanged();
isProgressVisible = true;
getDataFromServer(false);
}
});
}
});
现在，我没有收到错误，但是onLoadMore（）每次都会被调用两次，并且recyclerview中的视图每次都会刷新。我做错了什么？请查看logcat输出：
D/xx: Response => {…}
D/xx: Length = 9
D/xx: Query 'SELECT * FROM products' returned 9 rows
D/xx: Response => {…}
D/xx: Length = 9
D/xx: Query 'SELECT * FROM products' returned 18 rows
无法在滚动回调中调用此方法。滚动回调可能是在无法更改的度量和布局阶段运行theRecyclerView数据。任何可能会更改RecyclerView的结构或适配器内容应为推迟到下一帧。
警告本身是一种解释。 换句话说，您正在更新视图，而recyclerview正在计算布局尺寸。
出了什么问题？下面的实现-
mRecyclerViewAdapter.notifyItemChanged(listItems.size() - 1);
mRecyclerViewAdapter.notifyDataSetChanged();
您可以做的是将此UI操作发布到[[到下一个UI框架。您可以通过调用View.post()方法来执行此操作。
recyclerView.post(new Runnable() {
public void run() {
// There is no need to use notifyDataSetChanged()
mRecyclerViewAdapter.notifyItemInserted(allArticles.size() - 1);
}
});
recyclerViewAdapter：java：
recyclerView.post(new Runnable() {
public void run() {
mRecyclerViewAdapter.notifyDataSetChanged();
}
});
] >>kotlin：
recyclerView.post {
mRecyclerViewAdapter.notifyDataSetChanged()
}