java - RecyclerView 中的最后一项未显示

Question

我有一个工作正常的回收 View ，但是当项目数量太大而无法在屏幕上显示时，我向下滚动，最后一个项目不会显示。但是，我可以通过日志看到已成功创建并绑定(bind)了一个 View 持有者。然后，如果我添加另一个项目，则最后一个项目将显示在末尾，依此类推。如果您能帮助我，我将不胜感激。

public class ProdListAdapter extends RecyclerView.Adapter<ProdListItemViewHolder> implements Filterable {

    public List<ProductListItem> prodListItems = null;
    public List<ProductListItem> displayedProdListItems = null;
    private int currListItemId;
    private RecyclerView recyclerView;
    private ProductsListFragment fragment;
    private MainActivity activity;

    public ProdListAdapter(ProductsListFragment fragment, MainActivity activity) {
        System.out.println("LIST ADAPTER CONSTRUCTOR");
        this.prodListItems = new ArrayList<>();
        for (int i = 0; i < activity.products.size(); i++) {
            Product currProd = activity.products.get(i);
            System.out.println(currProd.getName() + " " + i);
            //add category separator
            if (i > 0 && !currProd.getCategory().equals(activity.products.get(i - 1).getCategory())) {
                prodListItems.add(new ProductListCategory(currProd));
            } else if (i == 0) {
                prodListItems.add(new ProductListCategory(currProd));
            }
            prodListItems.add(new ProductListItem(currProd));
        }

        this.activity = activity;
        this.displayedProdListItems = prodListItems;
        this.currListItemId = 0;
        this.fragment = fragment;
    }

    // Create new views (invoked by the layout manager)
    @Override
    public ProdListItemViewHolder onCreateViewHolder(ViewGroup parent, int viewType) {
        int idToUse = currListItemId % prodListItems.size();

        boolean isCatSeparator = false;
        ProductListItem currProdListItem =  prodListItems.get(idToUse);
        ConstraintLayout listItemView = (ConstraintLayout) LayoutInflater.from(parent.getContext())
                .inflate(R.layout.product_list_item, parent, false);
        if (currProdListItem.isCategorySeparator()) {
            isCatSeparator = true;
        }


        if (!isCatSeparator) {
            Product currProd = currProdListItem.getProduct();
        }


        System.out.println("CREATING: " + currProdListItem.getItemText());
        System.out.println("idToUse: " + idToUse + " " +  currProdListItem.getItemText());

        ProdListItemViewHolder  viewHolder = new ProdListItemViewHolder(listItemView, isCatSeparator, fragment, currProdListItem);
        currListItemId++;
        return viewHolder;
    }

    // (invoked by the layout manager)
    // Replace the contents of a view by the item at index: itemIndex
    @Override
    public void onBindViewHolder(ProdListItemViewHolder  viewHolder, int itemIndex) {
        // - get element from your dataset at this position
        // - replace the contents of the view with that element

        //update product item
        ProductListItem newListViewItem = displayedProdListItems.get(itemIndex);

        boolean newItemIsCatSeparator = newListViewItem.isCategorySeparator();
        boolean oldItemIsCatSeparator = viewHolder.getProductListItem().isCategorySeparator();


        if (!newItemIsCatSeparator) {
            Product currProd = newListViewItem.getProduct();
        }

        System.out.println();
        System.out.println(viewHolder.getProductListItem().getItemText() + " -> " + newListViewItem.getItemText());
        System.out.println(viewHolder.getProductListItem().isCategorySeparator() + " TO " + newListViewItem.isCategorySeparator());
        System.out.println("checked " + viewHolder.getProductListItem().isChecked() + " to " + newListViewItem.isChecked());
        System.out.println();

        if (newItemIsCatSeparator && oldItemIsCatSeparator) {
            //System.out.println("1");
            viewHolder.changeCategory(newListViewItem.getProduct());
        } else if (!newItemIsCatSeparator && !oldItemIsCatSeparator) {
            //System.out.println("2");
            viewHolder.changeProduct(newListViewItem);
        } else if (newItemIsCatSeparator && !oldItemIsCatSeparator) {
            //System.out.println("3");
            viewHolder.toCatSeparator(newListViewItem.getProduct());
        } else { // !newListViewItem.isCategorySeparator() && viewHolder.getProductListItem().isCategorySeparator()
            //System.out.println("4");
            viewHolder.toProdItem(newListViewItem);
        }
    }


    @Override
    public int getItemCount() {
        int count = 0;
        if(this.displayedProdListItems != null){
            count = displayedProdListItems.size();
        }
        return count;
    }
}

public class ProductsListFragment extends Fragment {
    private int numCheckedItems = 0;
    private BottomSheetBehavior botSheetBehavior;
    private boolean botSheetOpen = false;
    private ProdListAdapter prodAdapter;

    public View onCreateView(@NonNull LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState) {
        View root = inflater.inflate(R.layout.fragment_products_list, container, false);

        //recyclerView stuff below
        RecyclerView recyclerView = (RecyclerView) root.findViewById(R.id.prod_list_recycler_view);
        recyclerView.addItemDecoration(new DividerItemDecoration(getContext(), DividerItemDecoration.VERTICAL));
        // use this setting to improve performance if you know that changes
        // in content do not change the layout size of the RecyclerView


        LinearLayoutManager layoutManager = new LinearLayoutManager(this.getContext());
        recyclerView.setLayoutManager(layoutManager);

        prodAdapter = new ProdListAdapter(this, activity);
        recyclerView.setAdapter(prodAdapter);
        activity.setProdListAdapter(prodAdapter);

        return root;
    }
}

<?xml version="1.0" encoding="utf-8"?>
<androidx.constraintlayout.widget.ConstraintLayout
    xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:app="http://schemas.android.com/apk/res-auto"
    xmlns:tools="http://schemas.android.com/tools"
    android:id="@+id/prodListLayout"
    android:layout_width="match_parent"
    android:layout_height="match_parent">

    <AutoCompleteTextView
        android:id="@+id/searchTxtView"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:hint="Search"
        android:drawableLeft="@drawable/ic_search"
        android:drawablePadding="10dp"
        app:layout_constraintEnd_toEndOf="parent"
        app:layout_constraintStart_toStartOf="parent"
        app:layout_constraintTop_toTopOf="parent" />


    <androidx.recyclerview.widget.RecyclerView
        android:id="@+id/prod_list_recycler_view"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:dividerHeight="2dp"
        android:scrollbars="vertical"
        app:layout_constraintEnd_toEndOf="parent"
        app:layout_constraintStart_toStartOf="parent"
        app:layout_constraintTop_toBottomOf="@+id/searchTxtView" />

    <com.google.android.material.floatingactionbutton.FloatingActionButton
        android:id="@+id/fab"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_gravity="bottom|end"
        android:layout_margin="@dimen/fab_margin"
        android:layout_marginEnd="28dp"
        android:layout_marginRight="28dp"
        android:layout_marginBottom="28dp"
        android:src="@drawable/ic_fab_plus_36dp"
        app:backgroundTint="#aa00ff"
        app:layout_constraintBottom_toBottomOf="parent"
        app:layout_constraintEnd_toEndOf="parent" />


</androidx.constraintlayout.widget.ConstraintLayout>

Answer 1

添加:app:layout_constraintBottom_toBottomOf="parent"并将 recyclerview 的高度更改为 0dp