回收器视图通知数据集已更改 - 逻辑错误

Question

我知道notifyDataSetChanged（）适用于RecyclerView，因为我以前使用过它并且没有任何问题。但是在我当前的应用程序中，notifyDataSetChanged（）不会更新我的RecyclerView。如果有人能发现我的代码中的逻辑缺陷，将很高兴。

private List<ItemPetitionsTable> mAlVerified = new ArrayList<ItemPetitionsTable>();
private ViewPagerPetitionsRecyclerViewAdapter mViewPagerPetitionsRecyclerViewAdapter;
private RecyclerView mRecyclerView;
private StaggeredGridLayoutManager mStaggeredLayoutManager;

in onCreateView（）：

mAlVerified.clear();
mRecyclerView = (RecyclerView) view.findViewById(R.id.recyclerview_verified_petitions);
mRecyclerView.setHasFixedSize(true);
mStaggeredLayoutManager = new StaggeredGridLayoutManager(1, StaggeredGridLayoutManager.VERTICAL);
mRecyclerView.setLayoutManager(mStaggeredLayoutManager);
mViewPagerPetitionsRecyclerViewAdapter = new ViewPagerPetitionsRecyclerViewAdapter(activity, mAlVerified);
mRecyclerView.setAdapter(mViewPagerPetitionsRecyclerViewAdapter);

然后网络操作继续从服务器获取数据...并存储在本地数据库中。调用 getDataFromDatabase（） ...

private void getDataFromDatabase() {
        if (Const.DEBUGGING)
            Log.d(Const.DEBUG, "getDataFromDatabase()");
        if (mSwipeRefreshLayout.isRefreshing())
            mSwipeRefreshLayout.setRefreshing(false);
        mAlVerified = mPetitionsTableDbAdapter.getPetitionsForType(DatabaseHelper.PETITION_TYPE_ALL);
        Log.d(Const.DEBUG, "List Size: " + mAlVerified.size());
        mViewPagerPetitionsRecyclerViewAdapter.notifyDataSetChanged();
        isRefreshing = false;
    }

Logcat 显示列表包含新数据：但回收器视图未刷新。

50.018 21055-21055/com.xx.xxx D/xxx: getDataFromDatabase()
03-09 19:09:50.019 21055-21055/com.xx.xxx D/xxx: List Size: 10

如果您需要其他任何东西，请告诉我。

使用compile 'com.android.support:recyclerview-v7:23.1.1'如果这可能有帮助

public class ViewPagerPetitionsRecyclerViewAdapter extends RecyclerView.Adapter<ViewPagerPetitionsRecyclerViewAdapter.ViewHolder>
        implements Filterable {
    private List<ItemPetitionsTable> mItems = new ArrayList<>();
    private Context context;
    private SearchFilter searchFilter;
    // Provide a reference to the views for each data item
    // Complex data items may need more than one view per item, and
    // you provide access to all the views for a data item in a view holder
    public static class ViewHolder extends RecyclerView.ViewHolder {
        public TextView mTextView;
        public ImageView mImageView;
        public ViewHolder(View v) {
            super(v);
            mTextView = (TextView) v.findViewById(R.id.textView_description);
            mImageView = (ImageView) v.findViewById(R.id.imageView_main_image);
        }
    }
    // Provide a suitable constructor (depends on the kind of dataset)
    public ViewPagerPetitionsRecyclerViewAdapter(Context context, List<ItemPetitionsTable> items) {
        this.context = context;
        this.mItems = items;
        Log.d(Const.DEBUG, "mItems Size: " + items.size());
    }
    // Create new views (invoked by the layout manager)
    @Override
    public ViewPagerPetitionsRecyclerViewAdapter.ViewHolder onCreateViewHolder(ViewGroup parent,
                                                                               int viewType) {
        // create a new view
        View v = LayoutInflater.from(parent.getContext())
                .inflate(R.layout.item_viewpager_fragment_petitions, parent, false);
        // set the view's size, margins, paddings and layout parameters
        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, "onBindViewHolder(): " + position);
        String url = "http://xxx.org.in/Attachment/e-petition_img.jpg";
        if (mItems.get(position).getAttachments() == null
                || mItems.get(position).getAttachments().equalsIgnoreCase("")) {
            Picasso.with(context).load(url).into(holder.mImageView);
        } else {
            try {
                JSONArray array = new JSONArray(mItems.get(position).getAttachments());
                if (array.length() == 0)
                    url = "http://xxx.org.in/Attachment/e-petition_img.jpg";
                else {
                    for (int i = 0; i < array.length(); i++) {
                        JSONObject attachment_object = array.getJSONObject(i);
                        String type = attachment_object.getString("typ");
                        if (type.equalsIgnoreCase("i")) {
                            url = attachment_object.getString("Doc_path");
                        }
                    }
                }
            } catch (Exception e) {
                e.printStackTrace();
            }
            Picasso.with(context).load(url).into(holder.mImageView);
        }
        Typeface face = Typeface.createFromAsset(context.getAssets(),
                "fonts/RobotoSlab-Regular.ttf");
        holder.mTextView.setTypeface(face);
        holder.mTextView.setText(mItems.get(position).getPetition_title());

    }
    // Return the size of your dataset (invoked by the layout manager)
    @Override
    public int getItemCount() {
        return mItems.size();
    }
    @Override
    public Filter getFilter() {
        if (searchFilter == null)
            searchFilter = new SearchFilter();
        return searchFilter;
    }
    private class SearchFilter extends Filter {
        private PetitionsTableDbAdapter mPetitionsTableDbAdapter = DatabaseHelper.get(context).getPetitionsTableDbAdapter();
        @Override
        protected FilterResults performFiltering(CharSequence constraint) {
            FilterResults results = new FilterResults();
            if (constraint != null && constraint.length() > 0) {
                ArrayList<ItemPetitionsTable> searchResults = new ArrayList<ItemPetitionsTable>();
                for (ItemPetitionsTable item : mItems) {
                    if (item.getPetition_number().toLowerCase().contains(constraint.toString().toLowerCase())) {
                        searchResults.add(item);
                    }
                }
                results.count = searchResults.size();
                results.values = searchResults;
            } else {
                mItems = (ArrayList) mPetitionsTableDbAdapter.getPetitionsForType(DatabaseHelper.PETITION_TYPE_ALL);
                results.count = mItems.size();
                results.values = mItems;
            }

            return results;
        }
        @Override
        protected void publishResults(CharSequence constraint, FilterResults results) {
            mItems = (List<ItemPetitionsTable>) results.values;
            notifyDataSetChanged();
        }
    }

Answer 1

在

适配器中再创建一个方法，例如ViewPagerPetitionsRecyclerViewAdapter。使用该方法更新适配器中的日期，然后调用 notifyDataSetChanged（）

示例代码

     private void getDataFromDatabase() {
    if (Const.DEBUGGING)
        Log.d(Const.DEBUG, "getDataFromDatabase()");
    if (mSwipeRefreshLayout.isRefreshing())
        mSwipeRefreshLayout.setRefreshing(false);
    mAlVerified = mPetitionsTableDbAdapter.getPetitionsForType(DatabaseHelper.PETITION_TYPE_ALL);
    Log.d(Const.DEBUG, "List Size: " + mAlVerified.size());
   // u need to update data here
     mViewPagerPetitionsRecyclerViewAdapter.updatedata(mAlVerified);
    mViewPagerPetitionsRecyclerViewAdapter.notifyDataSetChanged();
    isRefreshing = false;
}