android - FirebaseRecyclerAdapter 无法将第一个布局识别为位置

Question

我的标题有点难以理解，但基本上当我将项目添加到我的数据库时，它应该显示在 RecyclerView 中。现在在我的 RecyclerView 中我有两个布局，但问题是我的数据库的第一项在我的其他布局中落后于我的第一项。因此，如果我的数据库中有 3 个项目，它只显示数据库中的 2 个项目，第一个项目隐藏在 RecyclerView 中我的第一个项目后面，这是一个完全不使用数据库的不同布局。

这是我的代码:

 FirebaseRecyclerOptions<Event> firebaseRecyclerOptions = new FirebaseRecyclerOptions.Builder<Event>()
            .setQuery(query1, Event.class).build();
    AccAdapter = new FirebaseRecyclerAdapter<Event, RecyclerView.ViewHolder>(firebaseRecyclerOptions){

        final static int TYPE_HEADER = 0;
        final static int TYPE_ITEM = 1;


        @Override
        public int getItemViewType(int position) {
            if (position == 0) return TYPE_HEADER;
            return TYPE_ITEM;
        }

        @Override
        public RecyclerView.ViewHolder onCreateViewHolder(ViewGroup parent, int viewType) {

            if (viewType == TYPE_HEADER){
                View view = LayoutInflater.from(getActivity()).inflate(R.layout.recycler_view_row_add_items,
                        parent, false);
                return new ProdudctHolder3(view);
            } else {
                View view = LayoutInflater.from(getActivity()).inflate(R.layout.recycler_view_row_acc,
                        parent, false);
                return new ProductHolder2(view);
            }
        }

        @Override
        protected void onBindViewHolder(final RecyclerView.ViewHolder holder, int position, final Event model) {
            if (holder instanceof ProdudctHolder3){
                ((ProdudctHolder3) holder).addBackground.setOnClickListener(new View.OnClickListener() {
                    @Override
                    public void onClick(View view) {
                        startActivity(new Intent(getActivity(), AccAddItems.class ));
                    }
                });
            } else{

                final ProductHolder2 productHolder2 = (ProductHolder2) holder;


                productHolder2.mName.setText(model.getName());
                productHolder2.view.setBackgroundResource(getBackgroundDrawable(Integer.valueOf(model.getProductAmount())));
                productHolder2.mbackground.setOnClickListener(new View.OnClickListener() {
                    @Override
                    public void onClick(View view) {

                        dialog = new Dialog(getActivity());
                        dialog.setContentView(R.layout.popup_edit_product);

                        SeekBar amountSeekBar = dialog.findViewById(R.id.amountSeekBar);
                        amountSeekBar.setMax(100);
                        amountSeekBar.setProgress(Integer.valueOf(model.getProductAmount()));
                        amountSeekBar.setOnSeekBarChangeListener(new SeekBar.OnSeekBarChangeListener() {
                            @Override
                            public void onProgressChanged(SeekBar seekBar, int i, boolean b) {
                                progress = i;
                            }

                            @Override
                            public void onStartTrackingTouch(SeekBar seekBar) {

                            }

                            @Override
                            public void onStopTrackingTouch(SeekBar seekBar) {
                                getRef(holder.getAdapterPosition()).child("productAmount").setValue(String.valueOf(progress));
                                dialog.dismiss();

                            }
                        });

                        dialog.show();

                    }
                });

                productHolder2.mbackground.setOnLongClickListener(new View.OnLongClickListener() {
                    @Override
                    public boolean onLongClick(View view) {
                        final PopupMenu popupMenu = new PopupMenu(getActivity(), productHolder2.mbackground);

                        popupMenu.inflate(R.menu.menu_acc);
                        popupMenu.setOnMenuItemClickListener(new PopupMenu.OnMenuItemClickListener() {
                            @Override
                            public boolean onMenuItemClick(MenuItem menuItem) {
                                switch (menuItem.getItemId()){
                                    case R.id.deleteProduct:
                                        getRef(productHolder2.getAdapterPosition()).removeValue();
                                        popupMenu.dismiss();
                                        return true;

                                    default:
                                        return false;
                                }
                            }
                        });

                        popupMenu.show();

                        return true;
                    }
                });

            }
        }

    };

    mAccRecyclerViewRef.setAdapter(AccAdapter);

我的两个产品持有人

私有(private)类 ProdudctHolder3 扩展了 RecyclerView.ViewHolder{

    private RelativeLayout addBackground;

    public ProdudctHolder3(View itemView) {
        super(itemView);
        addBackground = itemView.findViewById(R.id.mBackground2);
    }
}

private class ProductHolder2 extends RecyclerView.ViewHolder{

    private TextView mName;
    private RelativeLayout mbackground;
    private View view;

    public ProductHolder2(View itemView) {
        super(itemView);

        mName = itemView.findViewById(R.id.ItemName);
        mbackground = itemView.findViewById(R.id.mBackground1);
        view = itemView.findViewById(R.id.amountIndicator);

    }
}

Answer 1

理想的解决方案是在单个 RecyclerView 上设置两个适配器，但不幸的是，这是不可能的。但是，您可以制作一个处理两种类型项目的自定义适配器。我将通过举个例子来解释这一点。

假设您需要显示两种类型的对象，人类 和外星人。您的对象需要完全不同的布局和完全不同的 ViewHolders。请查看下面的 ViewHolders 代码:

public class MyAdapter extends RecyclerView.Adapter<RecyclerView.ViewHolder> {
    private static class HumanViewHolder extends RecyclerView.ViewHolder {
        public HumanViewHolder(View itemView) {
            super(itemView);

            //Prepare your ViewHolder
        }

        public void bind(Human human) {

            //Display your human object
        }
    }

    private static class AlienViewHolder extends RecyclerView.ViewHolder {
        public AlienViewHolder(View itemView) {
            super(itemView);

            //Prepare your ViewHolder
        }

        public void bind(Alien alien) {

            //Display your alien object
        }
    }
}

首先，您需要向适配器添加两个不同的常量来表示两种类型的 View :

private static final int ITEM_TYPE_HUMAN;
private static final int ITEM_TYPE_ALIEN;

为简单起见，我们还假设您将对象存储在列表中:

private List<Object> items = new ArrayList<>();

public MyAdapter(List<Object> items) {
    this.items.addAll(items);

    //Other stuff if needed
}

现在，您需要做的第一件事就是实现 getItemViewType() 方法:

@Override
public int getItemViewType(int position) {
    if (items.get(position) instanceof Human) {
        return ITEM_TYPE_HUMAN;
    } else {
        return ITEM_TYPE_ALIEN;
    }
} 

其次，您需要像这样在 onCreateViewHolder() 方法中使用项目类型:

@Override 
public RecyclerView.ViewHolder onCreateViewHolder(ViewGroup parent, int viewType)  {
    LayoutInflater layoutInflater = LayoutInflater.from(parent.getContext());

    if (viewType == ITEM_TYPE_HUMAN) {
        View view = layoutInflater.inflate(R.layout.item_human, parent, false);

        return new HumanViewHolder(view);
    } else {      
        View view = layoutInflater.inflate(R.layout.item_alien, parent, false);

        return new AlienViewHolder(view);
    } 
} 

最后，您只需要像这样绑定(bind)适当的 View 持有者:

@Override
public void onBindViewHolder(RecyclerView.ViewHolder viewHolder, int position) {
    Object item = items.get(position);

    if (viewHolder instanceof HumanViewHolder) {
        ((HumanViewHolder) viewHolder).bind((Human) item);
    } else {
        ((AlienViewHolder) viewHolder).bind((Alien) item);
    } 
}