我是Android应用程序开发的新手。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();
}
}
}
它执行一个方法，该方法位于AsyncTask类中。此方法从服务器下载数据，首先将其放入数据库，然后设置回收者视图适配器。问题在于有时滚动时会更改文本数据。 See attached video.
适配器的代码是：
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。
似乎您的代码中有一个拼写错误，请看一下，您的ViewHolder中有此错误：
public static TextView filmTitle;
但是您可以像处理其他字段一样使用它：
@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() + ...);
...
}
作为新手，为您提供的一些建议：只是..多注意您的代码，您将可以很好地进行编程：）