There is a simple plain Fragment containing RecyclerView

 public class PhotoGalleryFragment extends Fragment { public static final String TAG = "photoTag"; private RecyclerView mPhotoRecyclerView; private List<GalleryItem> mItems = new ArrayList<>(); private boolean loading = true; public int mPage = 1; @Override public void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState); setRetainInstance(true); new FetchItemsTask().execute(); } @Override public View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState) { View rootView = inflater.inflate(R.layout.fragment_photo_gallery, container, false); mPhotoRecyclerView = (RecyclerView) rootView.findViewById(R.id.fragment_photo_gallery_recyclerView); mPhotoRecyclerView.setLayoutManager(new GridLayoutManager(getActivity(), 3)); mPhotoRecyclerView.addOnScrollListener(new PhotoScrollListener()); setupAdapter(); return rootView; } private void setupAdapter() { if (isAdded()) { if (mPhotoRecyclerView.getAdapter() == null) mPhotoRecyclerView.setAdapter(new PhotoAdapter(mItems)); else mPhotoRecyclerView.getAdapter().notifyDataSetChanged(); } } private class PhotoScrollListener extends RecyclerView.OnScrollListener { private int pastVisiblesItems, visibleItemCount, totalItemCount; @Override public void onScrolled(RecyclerView recyclerView, int dx, int dy) { super.onScrolled(recyclerView, dx, dy); if (dy > 0) { visibleItemCount = mPhotoRecyclerView.getLayoutManager().getChildCount(); totalItemCount = mPhotoRecyclerView.getLayoutManager().getItemCount(); pastVisiblesItems = ((GridLayoutManager) mPhotoRecyclerView.getLayoutManager()). findFirstVisibleItemPosition(); if (loading) { if ((visibleItemCount + pastVisiblesItems) >= totalItemCount) { loading = false; Log.e(TAG, "LAST ITEM"); } } if (!loading) { loading = true; mPage++; new FetchItemsTask().execute(); } } } } private class PhotoHolder extends RecyclerView.ViewHolder { private TextView mTitleTextView; public PhotoHolder(View itemView) { super(itemView); mTitleTextView = (TextView) itemView; } public void bindGalleryItem(GalleryItem item) { mTitleTextView.setText(item.toString()); } } private class PhotoAdapter extends RecyclerView.Adapter<PhotoHolder> { private List<GalleryItem> mGalleryItems; public PhotoAdapter(List<GalleryItem> items) { mGalleryItems = items; } @Override public PhotoHolder onCreateViewHolder(ViewGroup parent, int viewType) { TextView textView = new TextView(getActivity()); return new PhotoHolder(textView); } @Override public void onBindViewHolder(PhotoHolder holder, int position) { GalleryItem item = mGalleryItems.get(position); holder.bindGalleryItem(item); } @Override public int getItemCount() { return mGalleryItems.size(); } } private class FetchItemsTask extends AsyncTask<Void, Void, List<GalleryItem>> { @Override protected List<GalleryItem> doInBackground(Void... params) { return new FlickrFetchr().fetchItems(mPage, mItems); } @Override protected void onPostExecute(List<GalleryItem> galleryItems) { mItems = galleryItems; // mItems.addAll(galleryItems); setupAdapter(); } } public static PhotoGalleryFragment newInstance() { PhotoGalleryFragment fragment = new PhotoGalleryFragment(); return fragment; } }

According to the logic of the ScrollListener upon reaching the edge of the list, AsyncTasc is launched, which starts the sending of the request, after which it is updated (supplemented with new elements) the list of RecyclerView'a elements

Please tell me how you can add the ability to visually display the download process (sending a request> receiving a response> parsing a response).

    2 answers 2

     private class FetchItemsTask extends AsyncTask<Void, Void, List<GalleryItem>> { ProgressBar progressBar = (ProgressBar) view.findViewById(R.id.progressBar); @Override protected void onPreExecute(){ progressBar.setVisibility(ProgressBar.VISIBLE); progressBar.getIndeterminateDrawable().setColorFilter(getResources().getColor(R.color.primary), android.graphics.PorterDuff.Mode.SRC_IN); } @Override protected List<GalleryItem> doInBackground(Void... params) { return new FlickrFetchr().fetchItems(mPage, mItems); } @Override protected void onPostExecute(List<GalleryItem> galleryItems) { mItems = galleryItems; // mItems.addAll(galleryItems); setupAdapter(); progressBar.setVisibility(ProgressBar.INVISIBLE); } }

    in XML

     <ProgressBar android:id="@+id/progressBar" android:visibility="invisible" android:background="#FFFFFF" android:layout_centerInParent="true" android:layout_centerHorizontal="true" android:layout_centerVertical="true" android:layout_width="wrap_content" android:layout_height="wrap_content" />
    • and in the second line where to get the view? After all, we have not blown up the main fragment yet - abbath0767
    • @ mamba0767 out of habit added) the solution helped?) - iFr0z
    • No, I tried the method you proposed with different options - in the end I used this method. stackoverflow.com/questions/4538338/progressdialog-in-asynctask But still thankful - abbath0767

    I used the following solution. In AsyncTasc finished off ProgressDialog . And my class inherited from AsyncTask began to look like this

     private class FetchItemsTask extends AsyncTask<Void, Void, List<GalleryItem>> { private ProgressDialog mProgressDialog; private Context c; public FetchItemsTask(Context c) { this.c = c; mProgressDialog = new ProgressDialog(c); } protected void onPreExecute() { this.mProgressDialog.setMessage("Loading"); this.mProgressDialog.show(); } @Override protected List<GalleryItem> doInBackground(Void... params) { return new FlickrFetchr().fetchItems(mPage, mItems); } @Override protected void onPostExecute(List<GalleryItem> galleryItems) { mItems = galleryItems; // mItems.addAll(galleryItems); setupAdapter(); if (mProgressDialog.isShowing()) { mProgressDialog.dismiss(); } } }