notifyDataSetChanged不工作的RecyclerView

问题描述

我收到来自服务器的数据，然后分析它并将其存储在一个列表。我使用这个列表中RecyclerView的适配器。我使用的片段。

I am getting data from server and then parsing it and storing it in a List. I am using this list for the RecyclerView's adapter. I am using Fragments.

我正在使用的Nexus 5与奇巧。我使用的支持库这一点。这是否会有所作为？

I am using a Nexus 5 with KitKat. I am using support library for this. Will this make a difference?

下面是我的code：（使用虚拟数据的问题）

Here is my code: (Using dummy data for the question)

成员变量：

List<Business> mBusinesses = new ArrayList<Business>();

RecyclerView recyclerView;
RecyclerView.LayoutManager mLayoutManager;
BusinessAdapter mBusinessAdapter;

我的 onCreateView（）：

@Override
public View onCreateView(LayoutInflater inflater, ViewGroup container,
        Bundle savedInstanceState) {

    // Getting data from server
    getBusinessesDataFromServer();

    View view = inflater.inflate(R.layout.fragment_business_list,
            container, false);
    recyclerView = (RecyclerView) view
            .findViewById(R.id.business_recycler_view);
    recyclerView.setHasFixedSize(true);

    mLayoutManager = new LinearLayoutManager(getActivity());
    recyclerView.setLayoutManager(mLayoutManager);

    mBusinessAdapter = new BusinessAdapter(mBusinesses);
    recyclerView.setAdapter(mBusinessAdapter);

    return view;
}

从服务器获取数据后， parseResponse（）之称。

protected void parseResponse(JSONArray response, String url) {
    // insert dummy data for demo

    mBusinesses.clear();

    Business business;

    business = new Business();
    business.setName("Google");
    business.setDescription("Google HeadQuaters");
    mBusinesses.add(business);

    business = new Business();
    business.setName("Yahoo");
    business.setDescription("Yahoo HeadQuaters");
    mBusinesses.add(business);

    business = new Business();
    business.setName("Microsoft");
    business.setDescription("Microsoft HeadQuaters");
    mBusinesses.add(business);

    Log.d(Const.DEBUG, "Dummy Data Inserted\nBusinesses Length: "
            + mBusinesses.size());

    mBusinessAdapter = new BusinessAdapter(mBusinesses);
    mBusinessAdapter.notifyDataSetChanged();
}

我的BusinessAdapter：

My BusinessAdapter:

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

    private List<Business> mBusinesses = new ArrayList<Business>();

    // Provide a reference to the type of views that you are using
    // (custom viewholder)
    public static class ViewHolder extends RecyclerView.ViewHolder {
        public TextView mTextViewName;
        public TextView mTextViewDescription;
        public ImageView mImageViewLogo;

        public ViewHolder(View v) {
            super(v);
            mTextViewName = (TextView) v
                    .findViewById(R.id.textView_company_name);
            mTextViewDescription = (TextView) v
                    .findViewById(R.id.textView_company_description);
            mImageViewLogo = (ImageView) v
                    .findViewById(R.id.imageView_company_logo);
        }
    }

    // Provide a suitable constructor (depends on the kind of dataset)
    public BusinessAdapter(List<Business> myBusinesses) {

        Log.d(Const.DEBUG, "BusinessAdapter -> constructor");

        mBusinesses = myBusinesses;
    }

    // Create new views (invoked by the layout manager)
    @Override
    public BusinessAdapter.ViewHolder onCreateViewHolder(ViewGroup parent,
            int viewType) {

        Log.d(Const.DEBUG, "BusinessAdapter -> onCreateViewHolder()");

        // create a new view
        View v = LayoutInflater.from(parent.getContext()).inflate(
                R.layout.item_business_list, parent, false);

        ViewHolder vh = new ViewHolder(v);
        return vh;
    }

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

        Log.d(Const.DEBUG, "BusinessAdapter -> onBindViewHolder()");

        Business item = mBusinesses.get(position);
        holder.mTextViewName.setText(item.getName());
        holder.mTextViewDescription.setText(item.getDescription());
        holder.mImageViewLogo.setImageResource(R.drawable.ic_launcher);

    }

    // Return the size of your dataset (invoked by the layout manager)
    @Override
    public int getItemCount() {

        Log.d(Const.DEBUG, "BusinessAdapter -> getItemCount()");

        if (mBusinesses != null) {
            Log.d(Const.DEBUG, "mBusinesses Count: " + mBusinesses.size());
            return mBusinesses.size();
        }
        return 0;
    }
}

但我不明白，在视图中显示的数据。我究竟做错了什么？

But I don't get the data displayed in the view. What am I doing wrong?

下面是我的日志，

07-14 21:15:35.669: D/xxx(2259): Dummy Data Inserted
07-14 21:15:35.669: D/xxx(2259): Businesses Length: 3
07-14 21:26:26.969: D/xxx(2732): BusinessAdapter -> constructor

我不明白这之后的任何日志。不应该 getItemCount（）适配器应该再次调用？

I don't get any logs after this. Shouldn't getItemCount() in adapter should be called again?

推荐答案

在你的 parseResponse（）正在创建的新实例的 BusinessAdapter 类，但实际上并没有使用任何地方，所以你的 RecyclerView 不知道新的实例存在。

In your parseResponse() you are creating a new instance of the BusinessAdapter class, but you aren't actually using it anywhere, so your RecyclerView doesn't know the new instance exists.

您要么需要：

• 呼叫 recyclerView.setAdapter（mBusinessAdapter）再次更新RecyclerView的适配器引用指向新的
• 或者直接删除 mBusinessAdapter =新BusinessAdapter（mBusinesses）; 继续使用现有的适配器。既然你没有更改 mBusinesses 参考，适配器将仍然使用数组列表，当你调用应正确更新 notifyDataSetChanged（）。

• Call recyclerView.setAdapter(mBusinessAdapter) again to update the RecyclerView's adapter reference to point to your new one
• Or just remove mBusinessAdapter = new BusinessAdapter(mBusinesses); to continue using the existing adapter. Since you haven't changed the mBusinesses reference, the adapter will still use that array list and should update correctly when you call notifyDataSetChanged().

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