通过另一个适配器访问适配器的数据

Question

是否可以通过另一个适配器访问适配器的数据？我想启动一个活动并将数据从适配器传递到一个片段，该片段在TabLayout中用作三个片段之一，我有两个适配器和一个点击按钮以启动一个活动，它的Java代码在我的第一个适配器中我需要通过第二个适配器本身传递第二个适配器的数据这里是我的代码：

我的第一个适配器

public class RecyclerViewDataAdapter extends RecyclerView.Adapter<RecyclerViewDataAdapter.ItemRowHolder>{

    private ArrayList<SectionDataModel> dataList;
    private Context mContext;
    private RecyclerView.RecycledViewPool recycledViewPool;
    private SnapHelper snapHelper;

    public RecyclerViewDataAdapter(ArrayList<SectionDataModel> dataList, Context mContext) {
        this.dataList = dataList;
        this.mContext = mContext;
        recycledViewPool = new RecyclerView.RecycledViewPool();
    }

    @Override
    public ItemRowHolder onCreateViewHolder(ViewGroup parent, int viewType) {
        View v = LayoutInflater.from(parent.getContext()).inflate(R.layout.list_item, null);
        ItemRowHolder rowHolder = new ItemRowHolder(v);
        snapHelper = new GravitySnapHelper(Gravity.START);
        return rowHolder;
    }

    @Override
    public void onBindViewHolder(ItemRowHolder holder, int position) {

        ArrayList singleSectionItems = dataList.get(position).getAllItemInSection();

        final String sectionName = dataList.get(position).getHeaderTitle();
        holder.itemTitle.setText(sectionName);

        SectionDataAdapter adapter = new SectionDataAdapter(singleSectionItems, mContext);
        holder.recyclerView.setHasFixedSize(true);
        holder.recyclerView.setLayoutManager(new LinearLayoutManager(mContext, LinearLayoutManager.HORIZONTAL, false));
        holder.recyclerView.setAdapter(adapter);
        holder.recyclerView.setRecycledViewPool(recycledViewPool);
        snapHelper.attachToRecyclerView(holder.recyclerView);


        holder.btnMore.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View view) {
//here i can start the activity but..(second adapter)
                Toast.makeText(view.getContext(), sectionName, Toast.LENGTH_SHORT).show();
            }
        });
    }

    @Override
    public int getItemCount() {
        return (null != dataList ? dataList.size() : 0);
    }

    public class ItemRowHolder extends RecyclerView.ViewHolder {
        protected ImageView mitemImage;
        protected TextView mitemtext;
        protected TextView itemTitle;
        protected RecyclerView recyclerView;
        protected Button btnMore;

        public ItemRowHolder(View itemView) {
            super(itemView);
            this.mitemImage = itemView.findViewById(R.id.itemImage);
            this.mitemtext = itemView.findViewById(R.id.tvTitle);
            this.itemTitle = itemView.findViewById(R.id.itemTitle);
            this.recyclerView = itemView.findViewById(R.id.recycler_view_list);
            this.btnMore = itemView.findViewById(R.id.btnMore);
        }
    }
} '

和我的第二个适配器：

import java.net.PortUnreachableException;
import java.util.ArrayList;

public class SectionDataAdapter extends RecyclerView.Adapter<SectionDataAdapter.SssingleItemRowHolder>{

    private ArrayList<SingleItemModel> itemModels;
    private Context mContext;

    public SectionDataAdapter(ArrayList<SingleItemModel> itemModels, Context mContext) {
        this.itemModels = itemModels;
        this.mContext = mContext;
    }

@Override
public SingleItemRowHolder onCreateViewHolder(ViewGroup parent, int viewType) {
    View v = LayoutInflater.from(parent.getContext()).inflate(R.layout.list_single_card, null);
    SingleItemRowHolder singleItemRowHolder = new SingleItemRowHolder(v);
    return singleItemRowHolder;
}

@Override
public void onBindViewHolder(SingleItemRowHolder holder, int position) {
    SingleItemModel itemModel = itemModels.get(position);
    holder.tvTitle.setText(itemModel.getName());
    holder.mitemImage.setImageResource(itemModel.getImage());

}


@Override
public int getItemCount() {
    return (null != itemModels ? itemModels.size() : 0);
}

public class SingleItemRowHolder extends RecyclerView.ViewHolder {

    protected TextView tvTitle;
    protected ImageView mitemImage;


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

        final Intent intent = new Intent(mContext,MainActivity.class);
        this.mitemImage = itemView.findViewById(R.id.itemImage);
        this.tvTitle = itemView.findViewById(R.id.tvTitle);
        itemView.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View view) {
//... need to start the activity from here
                Toast.makeText(view.getContext(), tvTitle.getText(), Toast.LENGTH_SHORT).show();
            }
        });

    }
}

Answer 1

就像@MilaDroid说你只需要一个返回另一个getter Adapter's的ArrayList<SingleItemModel>，但你将面临的问题是你需要从Adapter获得相同的Activity实例才能获得填充的ArrayList<SingleItemModel>。

一个好的解决方法是在Adapter中使用Bill Pugh的Singleton

public class Adapter {

private ArrayList<SingleItemModel> list;

private Adapter() {}

public static Adapter getInstance() {
    return InstInit.INSTANCE;
}

// Don't forget to set the list (or NPE)
// because we can't argue with a Singleton
public void setList(ArrayList<SingleItemModel> list) {
    this.list = list;
}

// You can now get the ArrayList
public ArrayList<SingleItemModel> getList() {
    return list;
}

private static class InstInit {
    private static final Adapter INSTANCE = new Adapter();
}

// Overrided RecyclerView.Adapter Methods
.................

}

假设以下ArrayList是Singleton，检索Adapters

AdapterOne a1 = AdapterOne.getInstance();
AdapterTwo a2 = AdapterTwo.getInstance();

ArrayList<SingleItemModel> a1RetrievedList = a1.getList();
// You don't need to create a new instance
// creating a new instance doesn't make sense
// because you need to repopulate the list
// for the new instance.

ArrayList<SingleItemModel> a2RetrievedList = a2.getList();
// You can also retrieve from AdapterTwo