Question

我是Android应用开发的新手。我有一个类，其中包含RecyclerView。

public class ScreenOne extends Fragment implements SwipeRefreshLayout.OnRefreshListener {

private RecyclerView mRecyclerView;
private FilmSetAdapter mAdapter;
private RecyclerView.LayoutManager mLayoutManager;

SwipeRefreshLayout mSwipeRefreshLayout;

RequestTask requestTask;
ArrayList<Film> listOfFilms;
ArrayList<Cinema> listOfCinemas;
ArrayList<String> cityIDs;

public ScreenOne() {
}

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

    View rootView = inflater.inflate(R.layout.screen_one, container,
            false);

    mRecyclerView = (RecyclerView) rootView.findViewById(R.id.recycler_view);
    mLayoutManager = new LinearLayoutManager(getActivity());
    //mRecyclerView.setHasFixedSize(true);
    mRecyclerView.setLayoutManager(mLayoutManager);
    //mRecyclerView.setItemAnimator(new DefaultItemAnimator());
    listOfFilms = new ArrayList<>();
    mAdapter = new FilmSetAdapter(listOfFilms);
    mRecyclerView.setAdapter(mAdapter);

    mSwipeRefreshLayout = (SwipeRefreshLayout) rootView.findViewById(R.id.refresh);
    mSwipeRefreshLayout.setOnRefreshListener(this);
    mSwipeRefreshLayout.setColorScheme(R.color.blue, R.color.cyan, R.color.grey_blue, R.color.lightblue);


    try {
        updateFilms();
    } catch (InterruptedException e) {
        e.printStackTrace();
    }


    return rootView;
}


private void updateFilms() throws InterruptedException {
    requestTask = new RequestTask();
    try {
        requestTask.execute().get();
    } catch (ExecutionException e) {
        e.printStackTrace();
    }
}

private boolean isNetworkConnected() {
    ConnectivityManager cm =
            (ConnectivityManager) getActivity().getSystemService(getActivity().CONNECTIVITY_SERVICE);
    NetworkInfo netInfo = cm.getActiveNetworkInfo();
    return netInfo != null && netInfo.isConnectedOrConnecting();
}

@Override
public void onRefresh() {
    Toast.makeText(getActivity(), R.string.refresh_started, Toast.LENGTH_SHORT).show();
    mSwipeRefreshLayout.setRefreshing(true);
    mAdapter.setDataset(new ArrayList<Film>());
    mAdapter.notifyDataSetChanged();
    try {
        updateFilms();
    } catch (InterruptedException e) {
        e.printStackTrace();
    }
    DatabaseHandler database = new DatabaseHandler(getActivity());
    mAdapter = new FilmSetAdapter(database.getAllFilms());
    mRecyclerView.swapAdapter(mAdapter, false);
    database.close();

    mSwipeRefreshLayout.postDelayed(new Runnable() {
        @Override
        public void run() {
            mSwipeRefreshLayout.setRefreshing(false);
            Toast.makeText(getActivity(), R.string.refresh_finished, Toast.LENGTH_SHORT).show();
        }
    }, 3000);
}

class RequestTask extends AsyncTask<Void, Void, Void> {

    protected void getPreferenciesCity()
    {
        cityIDs = new ArrayList<>();
        SharedPreferences sharedPref = getActivity().getPreferences(Context.MODE_PRIVATE);
        SharedPreferences sharedPrefs = PreferenceManager.getDefaultSharedPreferences(getActivity());
        Set<String> selections = sharedPrefs.getStringSet("cities", null);
        try {
            Log.d("SHARED PREFERENCES CITY", selections.toString());
            cityIDs.addAll(selections);
        }catch (NullPointerException e){Log.d("SHARED PREFERENCES CITY", "SP are empty");}

    }

    @Override
    protected void onPreExecute() {
        super.onPreExecute();
        listOfFilms = new ArrayList<>();
        getPreferenciesCity();
    }

    @Override
    protected Void doInBackground(Void... params) {
        if(isNetworkConnected()) {
            DatabaseHandler database = new DatabaseHandler(getActivity());
            database.clearFilms();
            try {
                HttpHandler httpHandler = new HttpHandler();
                listOfFilms = new ArrayList<>(httpHandler.listOfFilmsRequest(cityIDs));
                listOfCinemas = new ArrayList<>(httpHandler.listOfCinemasRequest());

                Film film;
                Cinema cinema;
                for (Iterator<Film> filmiterator = listOfFilms.iterator(); filmiterator.hasNext(); ) {
                    film = filmiterator.next();
                    if (database.isInDatabase(film.getID()))
                        database.updateFilm(film);
                    else
                        database.addFilm(film);
                }

                for (Iterator<Cinema> cinemaiterator = listOfCinemas.iterator(); cinemaiterator.hasNext(); ) {
                    cinema = cinemaiterator.next();
                    if (database.CinemaIsInDatabase(cinema.getIDCinema()))
                        database.updateCinema(cinema);
                    else
                        database.addCinema(cinema);
                }
                database.close();
            } catch (Exception e) {
                e.printStackTrace();
            }
            return null;
        }
        return null;
    }

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

        DatabaseHandler database = new DatabaseHandler(getActivity());
        mAdapter.setDataset(database.getAllFilms());
        mAdapter.notifyDataSetChanged();
    }

}

}

它执行一个放在AsyncTask类中的方法。此方法从服务器下载数据，首先将其放入数据库，然后设置回收器视图适配器。问题是有时文本数据在滚动时会发生变化。 See attached video.

适配器代码

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

private ArrayList<Film> mDataset;
final static String LOG_TAG = "FilmSetAdapter";

public void setDataset(ArrayList<Film> allFilms) {
    mDataset = new ArrayList<>(allFilms);
}

public static class ViewHolder extends RecyclerView.ViewHolder {
    public static TextView filmTitle;
    public TextView country;
    public TextView ticketsFrom;
    public TextView rating;
    public TextView format;
    public ImageView poster;
    public int id;

    public ViewHolder(final View itemView) {
        super(itemView);
        filmTitle = (TextView) itemView.findViewById(R.id.filmtitle);
        country = (TextView)itemView.findViewById(R.id.country);
        ticketsFrom = (TextView) itemView.findViewById(R.id.ticketsfrom);
        rating = (TextView)itemView.findViewById(R.id.rating);
        poster = (ImageView) itemView.findViewById(R.id.poster);
        format = (TextView) itemView.findViewById(R.id.format);
        format.setTypeface(null, Typeface.BOLD_ITALIC);
    }

}

@Override
public ViewHolder onCreateViewHolder(ViewGroup parent, int viewType) {
    View v = LayoutInflater.from(parent.getContext())
            .inflate(R.layout.cardview, parent, false);

    final ViewHolder vh = new ViewHolder(v);
    v.setOnClickListener(new View.OnClickListener() {
        @Override public void onClick(View v) {
            Log.d(LOG_TAG, "Нажата карточка. Вызов из activity "+v.toString());
            Intent intent = new Intent(v.getContext(),FilmInfoActivity.class);
            intent.putExtra("EXTRA_FILM_ID", vh.id);
            v.getContext().startActivity(intent);
        }
    });
    return vh;

}

@Override
public void onBindViewHolder(final ViewHolder holder, int position) {
    // - get element from your dataset at this position
    // - replace the contents of the view with that element
    holder.filmTitle.setText(mDataset.get(position).getTitle().toString()+" ID="+mDataset.get(position).getID()+" POS="+position);
    holder.country.setText(mDataset.get(position).getCountry());
    holder.ticketsFrom.setText(holder.ticketsFrom.getContext().getString(R.string.tickets_from) +
            mDataset.get(position).getRating().toString());
    holder.rating.setText(holder.rating.getContext().getString(R.string.rating_kinopoisk) +
            mDataset.get(position).getRating());
    holder.id = mDataset.get(position).getID();
    holder.format.setText(mDataset.get(position).getFormat());

    Picasso.with(holder.poster.getContext()).
            load(mDataset.get(position).getPoster()).
            skipMemoryCache().
            into(holder.poster);
}

@Override
public int getItemCount() {
    if(mDataset != null)
        return mDataset.size();
    return 0;
}

public FilmSetAdapter(ArrayList<Film> myDataset) {
    mDataset = new ArrayList<>(myDataset);
}

}

我不知道如何解决这个问题。请有人帮助我。

Answer 1

似乎您的代码中存在拼写错误，看看，您在ViewHolder中有：

    public static TextView filmTitle;

但是你和其他领域一样使用它：

@Override
public void onBindViewHolder(final ViewHolder holder, int position) {
    // - get element from your dataset at this position
    // - replace the contents of the view with that element
    holder.filmTitle.setText(mDataset.get(position).getTitle() + ...);
...   
}

作为一个新手给你一点建议：只需要更多关注你的代码，你就可以在编程方面做得很好：）

在滚动RecyclerView时更改cardview上的数据

1 个答案: