Recyclerview 视图不适用于 setNestedScrollingEnabled，它也从不回收任何视图

Question

我面临两个问题：

滚动侦听器将不起作用
当 RecyclerView 附加到 NestedScrollView 时，它从不回收任何视图。它就像 ScrollView 中的线性布局。它使用大量内存并造成滞后。

我在回收站视图顶部附加了一个 youtube 播放器片段，因为我无法将片段放入回收站视图中。在我的代码中你可以看到有一个框架布局。

我的布局是这样的：

    <android.support.v4.widget.NestedScrollView xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:app="http://schemas.android.com/apk/res-auto"
    android:id="@+id/nestedScroll"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:background="#ffffff"
    android:orientation="vertical">


    <LinearLayout
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:background="#ffffff"
        android:orientation="vertical">

        <LinearLayout
            android:layout_width="match_parent"
            android:layout_height="wrap_content"
            android:orientation="vertical">

            <FrameLayout               
                android:layout_width="match_parent"
                android:layout_height="240dp"
                android:layout_alignParentTop="true"/>





        </LinearLayout>


        <android.support.v7.widget.RecyclerView
            android:id="@+id/recycler_view"
            android:layout_width="match_parent"
            android:layout_height="wrap_content"
            android:layout_below="@+id/youtube_layout"
            android:visibility="visible"/>




    </LinearLayout>
</android.support.v4.widget.NestedScrollView>

我想使用滚动侦听器加载更多项目所以我尝试了以下方法：

@Override
public void onScrolled(RecyclerView recyclerView, int dx, int dy) {
    Log.i(TAG, "onScrolled: ");
    // bail out if scrolling upward or already loading data
    if (dy < 0 || dataLoading.isDataLoading()) return;

    final int visibleItemCount = recyclerView.getChildCount();
    final int totalItemCount = layoutManager.getItemCount();
    final int firstVisibleItem = layoutManager.findFirstVisibleItemPosition();

    if ((totalItemCount - visibleItemCount) <= (firstVisibleItem )) {
        onLoadMore();
    }


}

但是 layoutManager.findFirstVisibleItemPosition()==0 所以它不起作用，而且超过 onScrolled never called twice 因为我设置了 recyclerview.setNestedScrollingEnabled（假）

所以我在onBindView中试过这样

   public void onBindViewHolder(RecyclerView.ViewHolder customViewHolder, int i) {
    Log.w("d","inside bind view");

    if(i>=getItemCount()-1  &&   !datamanager.isDataLoading()){
        datamanager.loadmoreData();
    }

但是 recylerview 在我开始滚动之前一次性绑定所有视图，所以这个方法也不起作用。

Answer 1

这是我实现它的方法，我尝试将代码剥离到最低限度

public class DataAdapter extends RecyclerView.Adapter<RecyclerView.ViewHolder> {
    private static final int VIEW_TYPE_LOADING = 0;
    private static final int VIEW_TYPE_ITEM = 1;

    public boolean isLoading;
    private int visibleThreshold = 5;
    private int lastVisibleItem, totalItemCount;

    public ArrayList<Data> datas;

    private OnLoadMoreListener mOnLoadMoreListener;

    public DataAdapter(RecyclerView mRecyclerView, ArrayList<Data> datas) {
        this.datas = datas;

        final LinearLayoutManager linearLayoutManager = (LinearLayoutManager) mRecyclerView.getLayoutManager();
        mRecyclerView.addOnScrollListener(new RecyclerView.OnScrollListener() {
            @Override
            public void onScrolled(RecyclerView recyclerView, int dx, int dy) {
                super.onScrolled(recyclerView, dx, dy);

                totalItemCount = linearLayoutManager.getItemCount();
                lastVisibleItem = linearLayoutManager.findLastVisibleItemPosition();

                if (!isLoading && totalItemCount <= (lastVisibleItem + visibleThreshold)) {
                    if (mOnLoadMoreListener != null) {
                        DataAdapter.this.datas.remove(null);
                        mOnLoadMoreListener.onLoadMore();
                    }
                }
            }
        });
    }
    public static class DataObjectHolder extends RecyclerView.ViewHolder implements View.OnClickListener {
        //your views

        public DataObjectHolder(View itemView) {
            super(itemView);
            //initialize your views
        }

        @Override
        public void onClick(View v) {
            if (onItemClickListener != null) onItemClickListener.onItemClick(getAdapterPosition(), v);
        }
    }

    public void setOnItemClickListener(OnItemClickListener onItemClickListener) {
        this.onItemClickListener = onItemClickListener;
    }

    @Override
    public int getItemViewType(int position) {
        return datas.get(position) == null ? VIEW_TYPE_LOADING : VIEW_TYPE_ITEM;
    }

    @Override
    public RecyclerView.ViewHolder onCreateViewHolder(ViewGroup parent, int viewType) {
        if (viewType == VIEW_TYPE_ITEM) {
            View view = LayoutInflater.from(parent.getContext()).inflate(R.layout.list_item_data, parent, false);
            DataObjectHolder dataObjectHolder = new DataObjectHolder(view);
            return dataObjectHolder;
        } else if (viewType == VIEW_TYPE_LOADING) {
            View view = LayoutInflater.from(parent.getContext()).inflate(R.layout.layout_loading_item, parent, false);
            return new LoadingViewHolder(view);
        }
        return null;
    }

    @Override
    public void onBindViewHolder(final RecyclerView.ViewHolder hldr, final int position) {
        if (hldr instanceof DataObjectHolder) {
            final Data data = datas.get(position);
            final DataObjectHolder holder = (DataObjectHolder) hldr;

            //bind your views


        } else if (hldr instanceof LoadingViewHolder) {
            LoadingViewHolder loadingViewHolder = (LoadingViewHolder) hldr;

            if (isLoading) {
                loadingViewHolder.progressBar.setVisibility(View.VISIBLE);
                loadingViewHolder.progressBar.setIndeterminate(true);

                loadingViewHolder.tv_load_more.setVisibility(View.GONE);
                loadingViewHolder.tv_load_more.setOnClickListener(null);
            } else {
                loadingViewHolder.progressBar.setVisibility(View.GONE);

                loadingViewHolder.tv_load_more.setVisibility(View.VISIBLE);
                loadingViewHolder.tv_load_more.setOnClickListener(new View.OnClickListener() {
                    @Override
                    public void onClick(View view) {
                        if (mOnLoadMoreListener != null) {
                            datas.remove(null);
                            mOnLoadMoreListener.onLoadMore();
                        }
                    }
                });
            }
        }
    }

    @Override
    public int getItemCount() {
        return datas.size();
    }

    public void setOnLoadMoreListener(OnLoadMoreListener mOnLoadMoreListener) {
        this.mOnLoadMoreListener = mOnLoadMoreListener;
    }

}

loadingViewHolder 的 XML 如下所示，您基本上只是膨胀以获得持有人

<?xml version="1.0" encoding="utf-8"?>
<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
                android:layout_width="match_parent"
                android:layout_height="60dp">

    <ProgressBar
        android:id="@+id/progressBar1"
        android:layout_width="20dp"
        android:layout_height="20dp"
        android:layout_centerInParent="true"
        android:layout_gravity="center"
        android:indeterminate="true"/>

    <TextView
        android:id="@+id/tv_load_more"
        android:layout_width="match_parent"
        android:layout_height="match_parent"
        android:layout_centerInParent="true"
        android:gravity="center"
        android:text="Tap to load more"
        android:textSize="14sp"/>

</RelativeLayout>

希望这对您有所帮助

Answer 2

The recycler view never recycle any views when its attached to nested scroll view,its acts as set on linear layout inside scroll view.its create a huge memory and lags the screen.

没错。您不能将 RecyclerView 放入另一个滚动视图中。

不行，因为wrapping view需要知道RecyclerView的总高度，而RecyclerView只能通过测量和布局它的itemall来知道它的总高度.

如何解决这个问题？

不要将 RecyclerView 放在另一个滚动视图中。

如果您需要 header 或页脚，您必须将其添加到 RecyclerView 并让 RecyclerView 负责显示它。去掉你的 ScrollView 并把你的 header 移到 RecyclerView 的 里面。

从技术上讲，也可以在 RecyclerView 中加载片段，但我不得不承认让它正常工作有点棘手。

还有很多库可以促进这个过程，我个人最喜欢的是 Epoxy made by AirBnb, but there's also Groupie，还有很多其他库。

Answer 3

我遇到过这种情况。有一个recyclerview。回收站视图有 viewpager。 viewpager有fragments然后fragment里面有recyclerview

您需要破解触控才能使其完美滚动。

private boolean interceptTouch = true;
    private static final int MIN_DISTANCE = 200;
    private float downX = 0, downY = 0, moveX = 0, moveY = 0, upX = 0, upY;

    public TouchInterceptRecyclerView(Context context) {
        super(context);
    }

    public TouchInterceptRecyclerView(Context context, @Nullable AttributeSet attrs) {
        super(context, attrs);
    }


    @Override
    public boolean onInterceptTouchEvent(MotionEvent ev) {
        if (getRvTop() == 0) {
            onTouchEvent(ev);
        }
        return interceptTouch;
    }

    @Override
    public boolean onTouchEvent(MotionEvent event) {
        switch (event.getAction()) {
            case MotionEvent.ACTION_DOWN:
                downX = event.getX();
                downY = event.getY();
                break;
            case MotionEvent.ACTION_MOVE:
                moveX = event.getX();
                moveY = event.getY();
                break;
            case MotionEvent.ACTION_UP:
                upX = event.getX();
                upY = event.getY();
                break;
        }
        float deltaX = upX - downX;

        if (getViewTop() == 0 && moveY > downY && Math.abs(moveY - downY) > MIN_DISTANCE) {  // moving down
            interceptTouch = true;
        }else if (Math.abs(deltaX) > MIN_DISTANCE) {
            if (upX > downX) {    // Left to Right swipe action
                interceptTouch = false;
            }else {    // Right to left swipe action
                interceptTouch = false;
            }
        } else {  // screen tap
            interceptTouch = false;
        }
        return super.onTouchEvent(event);
    }

    @Override
    public boolean dispatchTouchEvent(MotionEvent ev) {
        return super.dispatchTouchEvent(ev);
    }

    @Override
    protected void onScrollChanged(int l, int t, int oldl, int oldt) {
        super.onScrollChanged(l, t, oldl, oldt);
    }

    @Override
    public void onScrolled(int dx, int dy) {
        if (getViewTop() <= 0) {
            interceptTouch = false;            // dispatch the touch to child when reached top
        } else {
            interceptTouch = true;           // do not dispatch the touch event
        }
        super.onScrolled(dx, dy);
    }

    public int getViewTop() {
        int top = 0;
        View v = this.getChildAt(1);
        if (v == null) {
            v = this.getChildAt(0);
        }
        if (v != null && v instanceof LinearLayout) {
            top = v.getTop();
        }
        return top;
    }

    public int getRvTop() {
        int top = -1;
        View v = this.getChildAt(1);
        if (v == null) {
            v = this.getChildAt(0);
        }
        if (v != null && v instanceof LinearLayout) {

            ViewPager vp = (ViewPager) v.findViewById(R.id.single_tribe_pager);
            if (vp != null) {
                int currentPos = vp.getCurrentItem();
                RecyclerView rv = (RecyclerView) vp.findViewWithTag("recyclerview" + currentPos);
                if (rv != null) {
                    View v1 = rv.getChildAt(0);
                    if (v1 != null && v1 instanceof CardView) {
                        top = v1.getTop() - ResourceUtils.getDimensionPixelOffset(R.dimen.padding_20);   // deducting 20 as we have give top margin as 20 to the top layout
                    }
                }
            }
        }
        return top;
    }

Recyclerview 视图不适用于 setNestedScrollingEnabled，它也从不回收任何视图

Recyclerview view is not working with setNestedScrollingEnabled and its never recycle any views also

android

android-recyclerview

android-nestedscrollview

onscrolllistener

如何解决这个问题？