我想把ListView改为RecyclerView。我想在RecyclerView中使用OnScrollListener的onScroll来确定用户是否滚动到列表的末尾。

我如何知道用户是否滚动到列表的末尾以便我可以从REST服务获取新数据?


当前回答

虽然接受的答案工作得很好,但下面的解决方案使用addOnScrollListener,因为setOnScrollListener已弃用,并减少了变量的数量,以及if条件。

final LinearLayoutManager layoutManager = new LinearLayoutManager(context);
feedsRecyclerView.setLayoutManager(layoutManager);

feedsRecyclerView.addOnScrollListener(new RecyclerView.OnScrollListener() {
    @Override
    public void onScrolled(RecyclerView recyclerView, int dx, int dy) {
        super.onScrolled(recyclerView, dx, dy);

        if (dy > 0) {   
            if ((layoutManager.getChildCount() + layoutManager.findFirstVisibleItemPosition()) >= layoutManager.getItemCount()) {
                Log.d("TAG", "End of list");
                //loadMore();
            }
        }
    }
});

其他回答

做这些变量。

private int previousTotal = 0;
private boolean loading = true;
private int visibleThreshold = 5;
int firstVisibleItem, visibleItemCount, totalItemCount;

设置为滚动回收视图。

mRecyclerView.addOnScrollListener(new RecyclerView.OnScrollListener() {

    @Override
    public void onScrolled(RecyclerView recyclerView, int dx, int dy) {
        super.onScrolled(recyclerView, dx, dy);

        visibleItemCount = mRecyclerView.getChildCount();
        totalItemCount = mLayoutManager.getItemCount();
        firstVisibleItem = mLayoutManager.findFirstVisibleItemPosition();

        if (loading) {
            if (totalItemCount > previousTotal) {
                loading = false;
                previousTotal = totalItemCount;
            }
        }
        if (!loading && (totalItemCount - visibleItemCount) 
            <= (firstVisibleItem + visibleThreshold)) {
            // End has been reached

            Log.i("Yaeye!", "end called");

            // Do something

            loading = true;
        }
    }
});

注意:确保你使用LinearLayoutManager作为RecyclerView的布局管理器。

LinearLayoutManager mLayoutManager;
mLayoutManager = new LinearLayoutManager(this);
mRecyclerView.setLayoutManager(mLayoutManager);

对于网格来说

GridLayoutManager mLayoutManager;
mLayoutManager = new GridLayoutManager(getActivity(), spanCount);
mRecyclerView.setLayoutManager(mLayoutManager);

有乐趣与你无尽的卷轴!!^ ^。

更新:mRecyclerView.setOnScrollListener()已弃用,只需替换为mRecyclerView.addOnScrollListener(),警告将消失!你可以从这个SO问题中读到更多。

由于Android现在正式支持Kotlin,这里是相同的更新-

使OnScrollListener

class OnScrollListener(val layoutManager: LinearLayoutManager, val adapter: RecyclerView.Adapter<RecyclerAdapter.ViewHolder>, val dataList: MutableList<Int>) : RecyclerView.OnScrollListener() {
    var previousTotal = 0
    var loading = true
    val visibleThreshold = 10
    var firstVisibleItem = 0
    var visibleItemCount = 0
    var totalItemCount = 0

    override fun onScrolled(recyclerView: RecyclerView, dx: Int, dy: Int) {
        super.onScrolled(recyclerView, dx, dy)

        visibleItemCount = recyclerView.childCount
        totalItemCount = layoutManager.itemCount
        firstVisibleItem = layoutManager.findFirstVisibleItemPosition()

        if (loading) {
            if (totalItemCount > previousTotal) {
                loading = false
                previousTotal = totalItemCount
            }
        }

        if (!loading && (totalItemCount - visibleItemCount) <= (firstVisibleItem + visibleThreshold)) {
            val initialSize = dataList.size
            updateDataList(dataList)
            val updatedSize = dataList.size
            recyclerView.post { adapter.notifyItemRangeInserted(initialSize, updatedSize) }
            loading = true
        }
    }
}

然后像这样把它添加到你的RecyclerView中

recyclerView.addOnScrollListener(OnScrollListener(layoutManager, adapter, dataList))

要获得完整的代码示例,请参阅Github repo。

 recyclerList.setOnScrollListener(new RecyclerView.OnScrollListener() 
            {
                @Override
                public void onScrolled(RecyclerView recyclerView, int dx,int dy)
                {
                    super.onScrolled(recyclerView, dx, dy); 
                }

                @Override
                public void onScrollStateChanged(RecyclerView recyclerView,int newState) 
                {
                    int totalItemCount = layoutManager.getItemCount();
                    int lastVisibleItem = layoutManager.findLastVisibleItemPosition();

                    if (totalItemCount> 1) 
                    {
                        if (lastVisibleItem >= totalItemCount - 1) 
                        {
                            // End has been reached
                            // do something 
                        }
                    }          
                }
            });  

我让你接近我。对我来说没问题。

我希望这对你有所帮助。

/**
 * Created by Daniel Pardo Ligorred on 03/03/2016.
 */
public abstract class BaseScrollListener extends RecyclerView.OnScrollListener {

    protected RecyclerView.LayoutManager layoutManager;

    public BaseScrollListener(RecyclerView.LayoutManager layoutManager) {

        this.layoutManager = layoutManager;

        this.init();
    }

    @Override
    public void onScrolled(RecyclerView recyclerView, int dx, int dy) {

        super.onScrolled(recyclerView, dx, dy);

        this.onScroll(recyclerView, this.getFirstVisibleItem(), this.layoutManager.getChildCount(), this.layoutManager.getItemCount(), dx, dy);
    }

    private int getFirstVisibleItem(){

        if(this.layoutManager instanceof LinearLayoutManager){

            return ((LinearLayoutManager) this.layoutManager).findFirstVisibleItemPosition();
        } else if (this.layoutManager instanceof StaggeredGridLayoutManager){

            int[] spanPositions = null; //Should be null -> StaggeredGridLayoutManager.findFirstVisibleItemPositions makes the work.

            try{

                return ((StaggeredGridLayoutManager) this.layoutManager).findFirstVisibleItemPositions(spanPositions)[0];
            }catch (Exception ex){

                // Do stuff...
            }
        }

        return 0;
    }

    public abstract void init();

    protected abstract void onScroll(RecyclerView recyclerView, int firstVisibleItem, int visibleItemCount, int totalItemCount, int dx, int dy);

}

我已经创建LoadMoreRecyclerView使用Abdulaziz Noor回答

LoadMoreRecyclerView

public class LoadMoreRecyclerView extends RecyclerView  {

    private boolean loading = true;
    int pastVisiblesItems, visibleItemCount, totalItemCount;
    //WrapperLinearLayout is for handling crash in RecyclerView
    private WrapperLinearLayout mLayoutManager;
    private Context mContext;
    private OnLoadMoreListener onLoadMoreListener;

    public LoadMoreRecyclerView(Context context) {
        super(context);
        mContext = context;
        init();
    }

    public LoadMoreRecyclerView(Context context, @Nullable AttributeSet attrs) {
        super(context, attrs);
        mContext = context;
        init();
    }

    public LoadMoreRecyclerView(Context context, @Nullable AttributeSet attrs, int defStyle) {
        super(context, attrs, defStyle);
        mContext = context;
        init();
    }

    private void init(){
        mLayoutManager = new WrapperLinearLayout(mContext,LinearLayoutManager.VERTICAL,false);
        this.setLayoutManager(mLayoutManager);
        this.setItemAnimator(new DefaultItemAnimator());
        this.setHasFixedSize(true);
    }

    @Override
    public void onScrolled(int dx, int dy) {
        super.onScrolled(dx, dy);

        if(dy > 0) //check for scroll down
        {
            visibleItemCount = mLayoutManager.getChildCount();
            totalItemCount = mLayoutManager.getItemCount();
            pastVisiblesItems = mLayoutManager.findFirstVisibleItemPosition();

            if (loading)
            {
                if ( (visibleItemCount + pastVisiblesItems) >= totalItemCount)
                {
                    loading = false;
                    Log.v("...", "Call Load More !");
                    if(onLoadMoreListener != null){
                        onLoadMoreListener.onLoadMore();
                    }
                    //Do pagination.. i.e. fetch new data
                }
            }
        }
    }

    @Override
    public void onScrollStateChanged(int state) {
        super.onScrollStateChanged(state);
    }

    public void onLoadMoreCompleted(){
        loading = true;
    }

    public void setMoreLoading(boolean moreLoading){
        loading = moreLoading;
    }

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

WrapperLinearLayout

public class WrapperLinearLayout extends LinearLayoutManager
{
    public WrapperLinearLayout(Context context, int orientation, boolean reverseLayout) {
        super(context, orientation, reverseLayout);
    }

    @Override
    public void onLayoutChildren(RecyclerView.Recycler recycler, RecyclerView.State state) {
        try {
            super.onLayoutChildren(recycler, state);
        } catch (IndexOutOfBoundsException e) {
            Log.e("probe", "meet a IOOBE in RecyclerView");
        }
    }
}

//在xml中添加

<your.package.LoadMoreRecyclerView
    android:id="@+id/recycler_view"
    android:layout_width="match_parent"
    android:layout_height="match_parent">
</your.package.LoadMoreRecyclerView>

OnCreate或onViewCreated

mLoadMoreRecyclerView = (LoadMoreRecyclerView) view.findViewById(R.id.recycler_view);
mLoadMoreRecyclerView.setOnLoadMoreListener(new OnLoadMoreListener() {
            @Override
            public void onLoadMore() {
                callYourService(StartIndex);
            }
        });

callYourService

private void callYourService(){
    //callyour Service and get response in any List

    List<AnyModelClass> newDataFromServer = getDataFromServerService();
    //Enable Load More
    mLoadMoreRecyclerView.onLoadMoreCompleted();

    if(newDataFromServer != null && newDataFromServer.size() > 0){
            StartIndex += newDataFromServer.size();

            if (newDataFromServer.size() < Integer.valueOf(MAX_ROWS)) {
                    //StopLoading..
                   mLoadMoreRecyclerView.setMoreLoading(false);
            }
    }
    else{
            mLoadMoreRecyclerView.setMoreLoading(false);
            mAdapter.notifyDataSetChanged();
    }
}

正如约翰·T所建议的。只需使用下面的代码块,真的很简短,美观简单:D

public void loadMoreOnRecyclerView() {
    mRecyclerView.addOnScrollListener(new RecyclerView.OnScrollListener() {
        @Override
        public void onScrolled(@NonNull @NotNull RecyclerView recyclerView, int dx, int dy) {
            super.onScrolled(recyclerView, dx, dy);
            if (!recyclerView.canScrollVertically(1) && dy != 0) {
                //Load more items here
            }
        }
    });
}

你可以跟随我的回购来了解它的工作方式。

https://github.com/Nghien-Nghien/PokeAPI-Java/blob/0d8d69d348e068911b883f0ae7791d904cc75cb5/app/src/main/java/com/example/pokemonapi/MainActivity.java

关于应用程序的描述信息如下:https://github.com/skydoves/Pokedex#readme