RecyclerView中的图像没有刷新

Question

About project. I am making an app, which takes data from website and shows it. Now, I am working on the ListFragment, which is responsible for getting titles, dates, authors and images, from the list of last 6 posts, then putting them in the storage, and from storage to the RecyclerView .

click to see the website

Everything works fine, when I am running ListFragment. But when i try to refresh my RecyclerView with my SwipeRefreshLayout it refreshes only String data, like titles, dates and authors. Refreshing images in RecyclerView istn't working.

For example. There is one new post on the website. I run my ListFragment without Internet connection, then turn Internet connection on and refresh RecyclerView swiping it down. Only String values are updated in RecyclerView items in a proper way, Images stay in the same places, despite there were downloaded new ones and put into the storage successfully.

How can I succesfully refresh images in my RecyclerView? Thanks for any help!

onCreateView() method of my ListFragment

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

    /* Inflating View */
    view = inflater.inflate(R.layout.fragment_list, container, false);

    ImageView banerImageView = view.findViewById(R.id.newsyBanerImageView);

    /* Enabling RecyclerView, and setting adapter for it */
    recyclerView = view.findViewById(R.id.recyclerView);

    layoutManager = new LinearLayoutManager(getContext());
    recyclerView.setLayoutManager(layoutManager);

    /* SwipeRefreshLayout varriable for recyclerView refreshing operations */
    swipeRefreshLayout = view.findViewById(R.id.swipeRefreshLayout);
    swipeRefreshLayout.setOnRefreshListener(this);

     /* Executing methods in TakeDataFromWebsite class. It dowloads data to save it to
    storage, then read it and put in UserInterface, in another Thread */
    new TakeDataFromWebSite().execute();
    swipeRefreshLayout.setRefreshing(true);

    /* enabling prograssbar */
    progressBar = view.findViewById(R.id.progressBar);

    return view;
}

onRefresh() method of my SwipeRefreshLayout

@Override
public void onRefresh() {
    new TakeDataFromWebSite().execute();
}

TakeDataFromWebsite class

public class TakeDataFromWebSite extends AsyncTask<Void, Void, Void> {

    //
    MyRecyclerAdapter recyclerAdapterInside = new MyRecyclerAdapter();

    /* In these ArrayLists is put Content from website, and saved to files, contentSources
    are adresses of articles contents */
    private ArrayList<String> titlesFromWebsite = new ArrayList<>();
    private ArrayList<String> datesFromWebsite = new ArrayList<>();
    private ArrayList<String> authorsFromWebsite = new ArrayList<>();
    private ArrayList<String> imagesSourcesFromWebsite = new ArrayList<>();
    private ArrayList<String> contentSourcesFromWebsite = new ArrayList<>();
    //
    private ArrayList<RequestCreator> imagesFromWebsite = new ArrayList<>();

    /* In these arraylists is put content, which is read from storage */
    private ArrayList<String> titlesFromStorage = new ArrayList<>();
    private ArrayList<String> datesFromStorage = new ArrayList<>();
    private ArrayList<String> authorsFromStorage = new ArrayList<>();
    private ArrayList<String> contentSourcesFromStorage = new ArrayList<>();
    //
    private ArrayList<File> imagesFromStorage = new ArrayList<>();



    /* Number of downloaded divs */
    int elementsCountFromWebsite;

    /* It's used to do not always check if website is available in another thread */
    boolean isUrlReachable = false;

    /* Method in new Thread */
    @Override
    protected Void doInBackground(Void... params) {

        if (isURLReachable(mContext, webSiteAddress)) {
            isUrlReachable = true;

            Document doc = new Document("doc");
            try {

                /* Getting whole document */
                doc = Jsoup.connect(webSiteAddress).get();

            } catch (Exception e) {
                e.printStackTrace();
                Log.e("ListFragment", "Doc from site getting Exception.");
            }

                /* Getting proper divs and spans */
                Elements postThumbDivs = doc.select("div[class=post-thumb]");
                Elements dates = doc.select("span[class=posted-on]");
                Elements authors = doc.select("span[class=author vcard]");

                /* Setting variable to number of post divs downloaded */
            elementsCountFromWebsite = postThumbDivs.size();

                /* Variables for iteration */
                Element postThumbDiv;
                Element date;
                Element author;

                for (int i = 0; i < elementsCountFromWebsite; i++) {

                    /* Getting titles and adding them to list */
                    postThumbDiv = postThumbDivs.get(i).select("a").first();
                    titlesFromWebsite.add(postThumbDiv.attr("title"));

                    /* Getting sources od articles contents and adding them to list */
                    postThumbDiv = postThumbDivs.get(i).select("a").first();
                    contentSourcesFromWebsite.add(postThumbDiv.attr("href"));

                    /* Getting images sources and adding them to list */
                    postThumbDiv = postThumbDivs.get(i).select("img").get(0);
                    imagesSourcesFromWebsite.add(postThumbDiv.attr("src"));

                    /* Adding picasso requestCreator to the arrayList, which is used to write
                     data in the storage later *  */
                    imagesFromWebsite.add(Picasso.get().load(postThumbDiv.attr("src")));

                    /* Getting dates and adding them to list */
                    date = dates.get(i).getElementsByTag("time").first();
                    datesFromWebsite.add(date.text());

                    /* Getting authors and adding them to list */
                    author = authors.get(i);
                    authorsFromWebsite.add(author.text());
                }
        }
        return null;
    }

    @Override
    protected void onPostExecute(Void aVoid) {
        super.onPostExecute(aVoid);

        /* If website is available write data to storage */
        if (isUrlReachable){
            write(mContext, titlesFromWebsite, fileName + "Titles");
            write(mContext, datesFromWebsite, fileName + "Dates");
            write(mContext, authorsFromWebsite, fileName + "Authors");
            write(mContext, imagesSourcesFromWebsite, fileName + "ImagesSources");
            write(mContext, contentSourcesFromWebsite, fileName + "ContentSources");

            for(int i = 0; i < elementsCountFromWebsite; i++){
                imagesFromWebsite.get(i).into
                        (picassoImageTarget(mContext, imagesDirectoryName, Integer
                                .toString(i) + ".png"));
            }


        } else{
            Snackbar.make(view, getText(R.string.brak_polaczenia_z_serwerem), Snackbar
                    .LENGTH_LONG).show();
        }

        /* Reading data from storage files. These arraylists are later sent to an adapter,
        whch uses them as a source of content */
        titlesFromStorage = readStringArraylist(mContext, fileName + "Titles");
        datesFromStorage = readStringArraylist(mContext, fileName + "Dates");
        authorsFromStorage = readStringArraylist(mContext, fileName + "Authors");
        contentSourcesFromStorage = readStringArraylist(mContext, fileName + "ContentSources");

        /* Number of elements taken from storage used while reading data from storage */
        int itemsCountFromStorage = titlesFromStorage.size();

        /* Getting Images from storage into file and adding to the files arraylist */
        ContextWrapper contextWrapper = new ContextWrapper(mContext);
        File directory = contextWrapper.getDir(imagesDirectoryName, Context.MODE_PRIVATE);
        for(int i = 0; i < itemsCountFromStorage; i++){

            File myImageFile = new File(directory, Integer.toString(i) + ".png");
            imagesFromStorage.add(myImageFile);

        }

        /* Setting FragmentManager to the recyclerAdapter */
        recyclerAdapterInside.setFragmentManager(getFragmentManager());

        /* Sending String Arraylist to an adapter */
        recyclerAdapterInside.setTitles(titlesFromStorage);
        recyclerAdapterInside.setDates(datesFromStorage);
        recyclerAdapterInside.setAuthors(authorsFromStorage);
        recyclerAdapterInside.setContentSources(contentSourcesFromStorage);

        /* Sending File Arraylist to an adapter */
        recyclerAdapterInside.setImages(imagesFromStorage);

        /* Context and directory sent from this fragment to an adapter. They are used for
        reading images from storage */
        recyclerAdapterInside.setmContext(mContext);
        recyclerAdapterInside.setImagesDirectoryName(imagesDirectoryName);

        /* Setting an adapter to the recyclerView. Not in CreateView() method, because it is
        need to be done after loading all data from storage*/
        recyclerAdapterInside.notifyDataSetChanged();
        swipeRefreshLayout.setRefreshing(false);
        recyclerView.setAdapter(recyclerAdapterInside);

    }

}

My RecyclerView.Adapter class

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

/* rraylists used to provide content */
private ArrayList<String> titles = new ArrayList<>();
private ArrayList<String> dates = new ArrayList<>();
private ArrayList<String> authors = new ArrayList<>();
private ArrayList<String> contentSources = new ArrayList<>();

/* Arraylist used, which i set with images from storage */
private ArrayList<File> images = new ArrayList<>();

/* Fragment with content of article and manager from  */
private ContentFragment contentFragment;
private FragmentManager fragmentManager;

/* Context and imagesDirectoryName from ListFragment */
private Context mContext;
private String imagesDirectoryName;

class ViewHolder extends RecyclerView.ViewHolder{

    public TextView itemTitleTextView;
    public TextView itemDateTextView;
    public TextView itemAuthorTextView;
    public ImageView itemImageView;
    public ImageView itemDateImageView;
    public ImageView itemAuthorImageView;



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

        itemTitleTextView = itemView.findViewById(R.id.itemTitleTextView);
        itemDateTextView = itemView.findViewById(R.id.itemDateTextView);
        itemAuthorTextView = itemView.findViewById(R.id.itemAuthorTextView);
        itemImageView = itemView.findViewById(R.id.itemImageView);
        itemDateImageView = itemView.findViewById(R.id.itemDateImageView);
        itemAuthorImageView = itemView.findViewById(R.id.itemAuthorImageView);


        itemView.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                int position = getAdapterPosition();

                contentFragment = new ContentFragment();

                /* Setting contentFragment attributes to proper values */
                contentFragment.setWebSiteAddress(contentSources.get(position));
                contentFragment.setItemIndex(position);
                contentFragment.setDate(dates.get(position));
                contentFragment.setAuthor(authors.get(position));
                contentFragment.setTitle(titles.get(position));
                contentFragment.setImagesDirectoryName(imagesDirectoryName);

                /* Fragment transaction process */
                FragmentTransaction transaction = fragmentManager.beginTransaction();
                transaction.replace(R.id.menuFragment, contentFragment);
                transaction.addToBackStack("contentFragment");
                transaction.commit();

                /* Test */
                Snackbar.make(v, "Click detected on item " + position, Snackbar.LENGTH_LONG)
                        .setAction("Action",null).show();
            }
        });
    }

}

@Override
public ViewHolder onCreateViewHolder(ViewGroup viewGroup, int i){
    View v = LayoutInflater.from(viewGroup.getContext()).inflate(R.layout.card_layout,
            viewGroup, false);
    ViewHolder viewHolder = new ViewHolder(v);
    return viewHolder;
}

@Override
public void onBindViewHolder(ViewHolder viewHolder, int i){
    viewHolder.itemTitleTextView.setText(titles.get(i));
    viewHolder.itemDateTextView.setText(dates.get(i));
    viewHolder.itemAuthorTextView.setText(authors.get(i));

    /* Process of reading images from arraylist and putting them to ImageViews */
    Picasso.get().load(images.get(i)).into(viewHolder.itemImageView);

}



@Override
public int getItemCount(){
    return titles.size();
}

public void setTitles(ArrayList<String> titles){
    this.titles = titles;
}

public void setDates(ArrayList<String> dates){
    this.dates = dates;
}

public void setAuthors(ArrayList<String> authors){
    this.authors = authors;
}

public void setContentSources(ArrayList<String> contentSources){
    this.contentSources = contentSources;
}

public void setFragmentManager(FragmentManager fragmentManager){
    this.fragmentManager = fragmentManager;
}

public void setmContext(Context mContext){
    this.mContext = mContext;
}

public void setImagesDirectoryName(String imagesDirectoryName) {
    this.imagesDirectoryName = imagesDirectoryName;
}

public void setImages(ArrayList<File> images){
    this.images = images;
}

}

Answer 1

You're notifying recyclerAdapterInside before providing it to recyclerview :

recyclerAdapterInside.notifyDataSetChanged();
swipeRefreshLayout.setRefreshing(false);
recyclerView.setAdapter(recyclerAdapterInside);

---

Just change that sequence inside your onPostExecute(Void aVoid) of your AsyncTask :

swipeRefreshLayout.setRefreshing(false);
recyclerView.setAdapter(recyclerAdapterInside); // Set adapter first.
recyclerAdapterInside.notifyDataSetChanged(); // Then notify for data change.

Note: Never try to update UI (ie Activity/Fragment) from AsyncTask , it may throw NullPointerException for UI view objects. Use Interface to communicate between UI and AsyncTask .