Question

我正在制作衣服应用程序，我需要制作无休止的recyclerview ..我可以获取所有数据，但无法进行分页，我尝试了许多解决方案，但没有任何效果，这就是我用于页面和图像的代码用于recyclerview数据的Firebase数据库。

firebase的图片

代码：

private View mMainView;
private String user_id;
private RecyclerView mUserList;
private DatabaseReference mUserDatabase;
private List<ItemsRecyclerView> mItems;
private ItemsAdapter itemsAdapter;
private GridLayoutManager gridLayoutManager;
private String oldestkey;


public Items() {
    // Required empty public constructor
}


@Override
public View onCreateView(LayoutInflater inflater, ViewGroup container,
                         Bundle savedInstanceState) {
    // Inflate the layout for this fragment
    mMainView = inflater.inflate(R.layout.fragment_items, container, false);
    mUserList = (RecyclerView) mMainView.findViewById(R.id.items_recyclerview);

    mItems = new ArrayList<>();

    gridLayoutManager = new GridLayoutManager(getActivity(),3);
    mUserList.setLayoutManager(gridLayoutManager);
    mUserList.setHasFixedSize(true);
    mUserList.addOnScrollListener(new RecyclerView.OnScrollListener() {
        @Override
        public void onScrolled(RecyclerView recyclerView, int dx, int dy) {
            super.onScrolled(recyclerView, dx, dy);

            Boolean reachedBottom = !recyclerView.canScrollVertically(1);

            if (reachedBottom){
                loadMoreMessages();
            }
        }
    });

    itemsAdapter = new ItemsAdapter(mItems);

    ViewCompat.setNestedScrollingEnabled(mUserList, false);
    ProfileAdmin activity = (ProfileAdmin) getActivity();
    user_id = activity.getMyData();

    mUserDatabase = FirebaseDatabase.getInstance().getReference().child("Items").child(user_id);

    mUserDatabase.keepSynced(true);

    loadItems();

    return mMainView;
}

private void loadMoreMessages() {
    mUserDatabase = FirebaseDatabase.getInstance().getReference().child("Items").child(user_id);

    Query itemsRef = mUserDatabase.orderByKey().startAt(oldestkey).limitToLast(10);

    itemsRef.addChildEventListener(new ChildEventListener() {
        @Override
        public void onChildAdded(@NonNull DataSnapshot dataSnapshot, @Nullable String s) {
            ItemsRecyclerView data = dataSnapshot.getValue(ItemsRecyclerView.class);

            oldestkey = dataSnapshot.getKey();

            mItems.add(data);

            itemsAdapter.notifyDataSetChanged();
            gridLayoutManager.scrollToPositionWithOffset(7,0);
        }

        @Override
        public void onChildChanged(@NonNull DataSnapshot dataSnapshot, @Nullable String s) {

        }

        @Override
        public void onChildRemoved(@NonNull DataSnapshot dataSnapshot) {

        }

        @Override
        public void onChildMoved(@NonNull DataSnapshot dataSnapshot, @Nullable String s) {

        }

        @Override
        public void onCancelled(@NonNull DatabaseError databaseError) {

        }
    });
}

public void loadItems(){
    mUserDatabase = FirebaseDatabase.getInstance().getReference().child("Items").child(user_id);
    Query query = mUserDatabase.orderByKey().limitToLast(10);

    query.addChildEventListener(new ChildEventListener() {
        @Override
        public void onChildAdded(@NonNull DataSnapshot dataSnapshot, @Nullable String s) {
            ItemsRecyclerView data = dataSnapshot.getValue(ItemsRecyclerView.class);


            for (DataSnapshot child : dataSnapshot.getChildren()){
                oldestkey = child.getKey();

                itemsAdapter.notifyDataSetChanged();
                //now add the list
                mItems.add(data);
                //now add the adapter
                mUserList.setAdapter(itemsAdapter);
            }

        }

        @Override
        public void onChildChanged(@NonNull DataSnapshot dataSnapshot, @Nullable String s) {

        }

        @Override
        public void onChildRemoved(@NonNull DataSnapshot dataSnapshot) {

        }

        @Override
        public void onChildMoved(@NonNull DataSnapshot dataSnapshot, @Nullable String s) {

        }

        @Override
        public void onCancelled(@NonNull DatabaseError databaseError) {

        }
    });
}

我希望有人能理解我并找到解决该问题的方法。

Answer 1

尝试将此滚动侦听器与recyclerview一起使用

在加载更多项目时，放置逻辑以加载更多项目

如果没有要加载的项目，

isLastPage将返回true

在获取数据时isLoading为true，在获取数据时为false

  import android.support.v7.widget.LinearLayoutManager;
    import android.support.v7.widget.RecyclerView;

    /**
     * Pagination class to add more items to the list when reach the last item.
     */
    public abstract class PaginationScrollListener extends RecyclerView.OnScrollListener {

        LinearLayoutManager layoutManager;

        /**
         * Supporting only LinearLayoutManager for now.
         *
         * @param layoutManager
         */
        public PaginationScrollListener(LinearLayoutManager layoutManager) {
            this.layoutManager = layoutManager;
        }

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

            int visibleItemCount = layoutManager.getChildCount();
            int totalItemCount = layoutManager.getItemCount();
            int firstVisibleItemPosition = layoutManager.findFirstVisibleItemPosition();

            if (!isLoading() && !isLastPage()) {
                if (visibleItemCount + firstVisibleItemPosition >= totalItemCount
                        && firstVisibleItemPosition >= 0
    //                    && totalItemCount >= ClothesFragment.itemsCount
                        ) {
                    loadMoreItems();
                }
            }
        }

        protected abstract void loadMoreItems();

        public abstract boolean isLastPage();

        public abstract boolean isLoading();

    }

将此添加到您的回收站视图

 public boolean isLastPage;
    public boolean isLoading;
 recyclerView.addOnScrollListener(new PaginationScrollListener(your layoutManager) {
            @Override
            protected void loadMoreItems() {
                isLoading=true;
                loadMoreItems();

            }

            @Override
            public boolean isLastPage() {
                return isLastPage;
            }

            @Override
            public boolean isLoading() {
                return isLoading;
            }
        });

   void loadMoreItems() {
        isLoading=false;

        after fetching your data assuming you have fetched list in your recyclerview
        adapter assuming your recyclerview adapter is rvAdapter
        rvAdapter.addData(list);
    }

现在在您的recyclerview适配器中添加以下方法

此列表是提供您recyclerview的列表

   void  addData(ArrayList<Object> list) {
            int size = this.list.size();
            this.list.addAll(list);
            int sizeNew = this.list.size();
            notifyItemRangeChanged(size, sizeNew);
        }

Answer 2

我建议您使用此lib XRecyclerView，它支持顶部加载视图和无穷的回收利用

ERROR in Module build failed:
var colors = require('./colors');
  ^Invalid CSS after "v": expected 1 selector or at-rule, was "var colors = requir"
      in /documents/project/node_modules/colors/lib/index.js

对于Firebase分页，您可以一次加载所有数据，并拥有两个保存数据xRecyclerView.setLoadingListener(this); @Override public void onRefresh() { } @Override public void onLoadMore() { }和List<Data> allData;的数组列表

假设您每次加载仅显示16个项目，因此在您的List<Data> adapterData;

onLoadMore() method

lastIndex是适配器中的一个变量，用于保存上次加载的索引

无休止的recyclerview无法正常工作

2 个答案: