展开/折叠嵌套的RecyclerView

Question

我有一个带有多个ViewHolders的RecyclerView适配器。每个ViewHolder都有一个标题TextView和一个嵌套的RecyclerView，它们工作正常。但是我想实现一个扩展/折叠功能，以便隐藏嵌套的RecyclerView，直到单击标题为止。我使用了这种方法RecyclerView expand/collapse items。它可以工作，但是当我单击标题以展开嵌套的recylerview时，recyclerview不会填充任何数据。明确地说，它检索数据，但不可见。任何想法为什么会这样？

这是我的onBindViewMethod：

public class EligibilityAdapter extends RecyclerView.Adapter<EligibilityAdapter.ViewHolder> {

private Context mContext;
private List<EligibilityDetails> mEligsList;
private List<Items> mItemslist;
private LayoutInflater inflater;
private int mExpandedPosition = -1;

public EligibilityAdapter(Context context, List<EligibilityDetails> eligsList) {
    mContext = context;
    mEligsList = eligsList;
    inflater = LayoutInflater.from(context);
}

@Override
public int getItemViewType(int position) {
    switch (position) {
        case 0:
            return R.layout.rv_eligs_item_domestic;
        case 1:
            return R.layout.rv_eligs_item_overseas;
        default:
            return R.layout.rv_eligs_item_military;
    }
}

@NonNull
@Override
public ViewHolder onCreateViewHolder(@NonNull ViewGroup viewGroup, int i) {
    inflater = LayoutInflater.from(viewGroup.getContext());
    View view = inflater.inflate(i, viewGroup, false);
    ViewHolder holder = null;
    switch (i) {
        case R.layout.rv_eligs_item_domestic:
            holder = new DomesticViewHolder(view);
            break;
        case R.layout.rv_eligs_item_overseas:
            holder = new OverseasViewHolder(view);
            break;
        case R.layout.rv_eligs_item_military:
            holder = new MilitaryViewHolder(view);
            break;
    }
    return holder;
}

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

public abstract class ViewHolder extends RecyclerView.ViewHolder {
    RecyclerView itemsRv;
    TextView mHeader;
    ItemsAdapter adapter;

    public ViewHolder(View itemView) {
        super(itemView);
        mHeader = (TextView) itemView.findViewById(R.id.header_tv);
        itemsRv = itemView.findViewById(R.id.recyclerViewItems);
    }
    public void setData(List<Items> list) {
        adapter.updateList(list);
    }
    abstract void bind(EligibilityDetails item);
}

public class DomesticViewHolder extends ViewHolder {

    TextView mHeader;
    RecyclerView itemsRv;
    ItemsAdapter adapter;

    public DomesticViewHolder(View itemView) {
        super(itemView);
        mHeader = (TextView) itemView.findViewById(R.id.header_tv);
        itemsRv = itemView.findViewById(R.id.recyclerViewItems);
    }
    public void setData(List<Items> list) {
        adapter.updateList(list);
    }
    @Override
    void bind(EligibilityDetails eligibilityDetails) {
        mHeader.setText(eligibilityDetails.getRequirementHeader());
        mItemslist = eligibilityDetails.getItemsList();
        ItemsAdapter itemsAdapter = new ItemsAdapter(mContext, mItemslist);
        itemsRv.setHasFixedSize(true);
        itemsRv.setLayoutManager(new CustomLinearLayoutManager(mContext));
        itemsRv.setAdapter(itemsAdapter);
        itemsRv.setNestedScrollingEnabled(false);
    }
}

public class OverseasViewHolder extends ViewHolder {

    TextView mHeader;
    RecyclerView itemsRv;
    ItemsAdapter adapter;

    public OverseasViewHolder(View itemView) {
        super(itemView);
        mHeader = (TextView) itemView.findViewById(R.id.header_tv);
        itemsRv = itemView.findViewById(R.id.recyclerViewItems);
    }
    public void setData(List<Items> list) {
        adapter.updateList(list);
    }

    @Override
    void bind(EligibilityDetails eligibilityDetails) {
        mHeader.setText(eligibilityDetails.getRequirementHeader());
        mItemslist = eligibilityDetails.getItemsList();
        ItemsAdapter itemsAdapter = new ItemsAdapter(mContext, mItemslist);
        itemsRv.setHasFixedSize(true);
        itemsRv.setLayoutManager(new CustomLinearLayoutManager(mContext));
        itemsRv.setAdapter(itemsAdapter);
        itemsRv.setNestedScrollingEnabled(false);
    }
}

public class MilitaryViewHolder extends ViewHolder {

    TextView mHeader;
    RecyclerView itemsRv;
    ItemsAdapter adapter;

    public MilitaryViewHolder(View itemView) {
        super(itemView);
        mHeader = (TextView) itemView.findViewById(R.id.header_tv);
        itemsRv = itemView.findViewById(R.id.recyclerViewItems);
    }
    public void setData(List<Items> list) {
        adapter.updateList(list);
    }

    @Override
    void bind(EligibilityDetails eligibilityDetails) {
        mHeader.setText(eligibilityDetails.getRequirementHeader());
        mItemslist = eligibilityDetails.getItemsList();
        final ItemsAdapter itemsAdapter = new ItemsAdapter(mContext, mItemslist);
        itemsRv.setHasFixedSize(true);
        itemsRv.setLayoutManager(new CustomLinearLayoutManager(mContext));
        itemsRv.setAdapter(itemsAdapter);
        itemsRv.setNestedScrollingEnabled(false);
    }
}

@Override
public void onBindViewHolder(@NonNull final EligibilityAdapter.ViewHolder viewHolder, int i) {
    viewHolder.bind(mEligsList.get(i));

    final boolean isExpanded = i == mExpandedPosition;
    viewHolder.itemsRv.setVisibility(isExpanded?View.VISIBLE:View.GONE);
    viewHolder.itemView.setActivated(isExpanded);
    viewHolder.itemView.setOnClickListener(new View.OnClickListener() {
        @Override
        public void onClick(View v) {
            mExpandedPosition = isExpanded ? -1:viewHolder.getAdapterPosition();
            ItemsAdapter itemsAdapter = new ItemsAdapter(mContext, mItemslist);
            viewHolder.itemsRv.setAdapter(itemsAdapter);
            //TransitionManager.beginDelayedTransition(recyclerView);
            notifyDataSetChanged();
        }
    });
}

其中itemsRv是嵌套的RecyclerView。 我尝试将这种逻辑移到各个视图持有者，并在这里将recyclerview逻辑移到这里，就像在onClick方法中设置适配器一样。每次出现空白。

谢谢。

Answer 1

您可以创建一个多视图类型的适配器，而不是为每个标头添加一个新的子Recyclerview，该适配器将为您的标头提供一个视图类型，并为您的子项提供一个视图类型。

使用通用类型将数据类型转换为自己的视图类型，而不是仅将标题数据项用于数据列表。

要做到这一点，我们需要创建一个空接口，所有数据类型都将以这种方式实现它们都是通用的。

public interface GenericDataType {}

因此您的数据类型将如下所示

class HeaderItem implements GenericDataType {
    //All of your pojo data
    List<ChildrenItem> childrens; //ChildrenItem will also implement the GenericDataType that way both of the items are acceptable
}

所以我们做到了，我们可以替换当前的项目

private List<EligibilityDetails> mEligsList;
private List<Items> mItemslist;

收件人

private List<GenericDataType> adapterItems;

现在，我们需要确保只要我们有某个ViewHolder，该职位​​的项目就会是正确的类型。为此，我们需要更改getItemViewType

@Override
public int getItemViewType(int position) {
    GenericItem currentItem = adapterItems.get(position);

    if (currentItem instanceOf HeaderItem) { //We have to use if else becasue java's switch does not supprt checking instancesOf
        return R.layout.your_header_item_layout_id;

    } else if(currentItem instanceOf ChildrenItem) {
        return R.layout.your_children_item_layout_id;

    } else if(repeat for any other types you have) {
        return R.layout.your_other_item_layout_id;

    } else {
        throw new Throwable("Unsupported type"); //This should never happen but we add it to make the compiler compile
    }
}

现在，我们终于可以更改我们的onBind方法以支持两种类型

@Override
public void onBindViewHolder(@NonNull final  EligibilityAdapter.ViewHolder viewHolder, int i) {

    if (viewHolder instanceOf HeaderViewHolder) {
        HeaderViewHolder holder = (HeaderViewHolder) viewHolder;
        headerItem = (HeaderItem) items.get(i);
        //Do rest of binding here

        holder.viewToAddMoreItems.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                if (!headerItem.isEpanded()) { //Add to your header type a Boolean to check if it is expanded or not 
                    adapterItems.addAll(headerItem.getChildrens()); //They are the same generic type but the getItemViewType will handle it for us
                    notifyItemRangeInserted(); //Provied item start index and size of the list
                } else {
                    adapterItems.removeAll(headerItem.getChildrens());
                    notifyItemRangeRemoved(); I don't remember what it require but you'll figure that out
                }
                headerItem.setExpanded(!headerItem.isExpanded()); //Flipping the value 
            }
        });

    } else if (viewHolder instanceOf ChildrenViewHolder) {
            ChildrenViewHolder holder = (ChildrenViewHolder) viewHolder;
            childrenItem = (ChildrenItem) items.get(i);
            //Do your binding here

    } else if(repeate for other view-types) {}
}