Recyclerview-无法在滚动回调中调用此方法 [英] Recyclerview - cannot call this method in a scroll callback
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问题描述
我在StackOverflow中已经多次看到此问题，但无法解决该问题.所以伸出援助之手.
I have seen this question many times in StackOverflow, but I couldn't get the issue fixed. So reaching out for help.
请注意:我已经检查了SO上的其他问题，尽管我可以摆脱该错误，但是还有其他问题.
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);
}
}
}
我之前的代码:
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:
With my old code, I get the following 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，我如下进行了修改:
So as suggested on various StackOverflow answers, I modified it like below:
修改后的代码可查看各种答案:
modified code looking at various answers:
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()每次都被调用两次，并且recyclerview中的视图每次都保持刷新.我做错了什么?请查看logcat输出:
Now, I don't get the error, but the onLoadMore() is called twice, everytime and the views in recyclerview keep refreshing everytime. What is it I am doing wrong? Please see the logcat output:
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
推荐答案
无法在滚动回调中调用此方法.滚动回调可能是 在测量期间运行无法更改的布局通行证 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.
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.
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.
The warning itself is an explaination. In other words, you are updating a view while recyclerview is calculating layout measurements.
出了什么问题? 下面的实现-
What went wrong? The implementation below -
mRecyclerViewAdapter.notifyItemChanged(listItems.size() - 1);
mRecyclerViewAdapter.notifyDataSetChanged();
您可以做的就是将此UI操作发布到下一个UI框架.您可以通过调用View.post()方法来执行此操作.
What you can do is post this UI operation to the next UI frame. You can do this by calling View.post() method.
recyclerView.post(new Runnable() {
public void run() {
// There is no need to use notifyDataSetChanged()
mRecyclerViewAdapter.notifyItemInserted(allArticles.size() - 1);
}
});
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