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FragmentStateAdapter onRefreshListener

how can i implement a onRefreshListener in fragments if i am using ViewPager (ViewPager 2) with FragmentStateAdapter.
I found only examples with FragmentPageAdapter.
the other code works so far, i mean swiping between fragments an displaying a list of strings.
Just the refresh (pull from top to bottom) don't work.
I just see the refresh symbol short and then it dissapears.
In the debugger the onRefresh functions will not be called, after a refresh action.
This is my Code:
main activity
viewPager = findViewById(R.id.view_pager);
tabLayout = findViewById(R.id.tabs);
viewPager.setAdapter(new ViewPagerAdapter(this, dataManager));
new TabLayoutMediator(tabLayout, viewPager,
new TabLayoutMediator.TabConfigurationStrategy() {
#Override public void onConfigureTab(#NonNull TabLayout.Tab tab, int position) {
tab.setText("Tab " + (position + 1));
}
}).attach();
viewpager
public class ViewPagerAdapter extends FragmentStateAdapter {
private static final int CARD_ITEM_SIZE = 3;
private DataManager dataManager;
public ViewPagerAdapter(#NonNull FragmentActivity fragmentActivity, DataManager dataManager) {
super(fragmentActivity);
this.dataManager = dataManager;
}
#NonNull #Override public Fragment createFragment(int position) {
Fragment fragment = null;
if (position == 0)
{
fragment = new FragmentA();
Bundle bundle = new Bundle(2);
bundle.putString("TOKEN", dataManager.getToken());
bundle.putString("SERVER_URL", dataManager.getServerURL());
fragment.setArguments(bundle);
}
else if (position == 1)
{
fragment = new FragmentB();
}
else if (position == 2)
{
fragment = new FragmentC();
}
return fragment;
}
#Override public int getItemCount() {
return CARD_ITEM_SIZE;
}
fragment
public class FragmentA extends Fragment implements SwipeRefreshLayout.OnRefreshListener{
private RecyclerView recyclerView;
private SwipeRefreshLayout swipeLayout;
private Bundle bundle;
private ListView mainListView;
private LibrariesAdapter listAdapter;
private LibraryDataManager libraryDataManager;
private RecyclerViewAdapter adapter;
private GetLibrariesTask getLibrariesTask;
private String token;
private String serverUrl;
#Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
bundle = getArguments();
if (bundle != null) {
token = bundle.getString("TOKEN");
serverUrl = bundle.getString("SERVER_URL");
libraryDataManager = new LibraryDataManager(token, serverUrl);
} else {
// ToDo show error or something else
}
}
#Nullable
#Override
public View onCreateView(LayoutInflater inflater, #Nullable ViewGroup container, #Nullable Bundle savedInstanceState) {
View rootView = inflater.inflate(
R.layout.fragment, container, false);
swipeLayout = rootView.findViewById(R.id.swiperefresh);
getLibrariesTask = new GetLibrariesTask();
getLibrariesTask.execute();
return rootView;
}
#Override
public void onViewCreated(View view, #Nullable Bundle savedInstanceState) {
super.onViewCreated(view, savedInstanceState);
mainListView = view.findViewById(android.R.id.list);
ArrayList<Library> librariesList = new ArrayList<>();
listAdapter = new LibrariesAdapter(getActivity(), librariesList);
mainListView.setAdapter(listAdapter);
swipeLayout.setOnRefreshListener(this);
swipeLayout.setOnRefreshListener(new SwipeRefreshLayout.OnRefreshListener() {
#Override
public void onRefresh() {
getLibrariesTask = new GetLibrariesTask();
getLibrariesTask.execute();
}
});
}
private class GetLibrariesTask extends AsyncTask<Void, Void, List<Library>> {
#Override
protected List<Library> doInBackground(Void... args) {
List<Library> libraries = libraryDataManager.getLibraries();
return libraries;
}
#Override
protected void onPostExecute(List<Library> libraries) {
listAdapter.clear();
listAdapter.addAll(libraries);
listAdapter.notifyDataSetChanged();
Logger.debug("on refresh2");
// swipeLayout.setRefreshing(false);
}
}
}

Strange behavior of OnItemClickListener inside RecyclerView inside Fragment

Need help with android app (java)
My app starts with SplashActivity. During it I`m getting json via retrofit request and after successfull response I fill my DB
SplashActivity
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_splash);
ISplashInteractor splashInteractor = new SplashInteractor();
moviePresenter = new MoviePresenter(this, splashInteractor);
moviePresenter.initDB();
}
after DB successfully loaded automatically starts MovieListActivity
public class MovieListActivity extends AppCompatActivity {
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_movie_list);
FragmentManager fragmentManager = getSupportFragmentManager();
FragmentTransaction transaction = fragmentManager.beginTransaction();
Fragment allMoviesFragment = new AllMoviesFragment();
String tag = "MovieList";
transaction.replace(R.id.main_container, allMoviesFragment, tag);
transaction.commit();
}
}
and at once list of movies loads inside inner fragment AllMoviesFragment(inside recyclerView). till this point everything is ok.
now I set onRecyclerViewItemClickListener - it must open another fragment inside MovieListActivity but instead of this - my app restarts from begining and I observe loading of SpalshActivity again(I put progressbar during request) and again my RecyclerView...
my RecyclerViewAdapter
public class RecyclerViewAdapter extends RecyclerView.Adapter<RecyclerViewAdapter.ViewHolder> {
private List<MovieDetails> movieList;
private OnRecyclerViewItemClickListener onRecyclerViewItemClickListener;
public RecyclerViewAdapter(List<MovieDetails> movieList) {
this.movieList = movieList;
}
public void setOnRecyclerViewItemClickListener(OnRecyclerViewItemClickListener onRecyclerViewItemClickListener){
this.onRecyclerViewItemClickListener = onRecyclerViewItemClickListener;
}
#Override
public ViewHolder onCreateViewHolder(ViewGroup parent, int viewType) {
View v = LayoutInflater.from(parent.getContext()).inflate(R.layout.simple_selectable_list_item, parent, false);
return new ViewHolder(v);
}
#Override
public void onBindViewHolder(ViewHolder holder, int position) {
MovieDetails movieDetails = (movieList.get(position));
holder.name.setText(movieDetails.getTitle());
holder.year.setText(String.valueOf(movieDetails.getReleaseYear()));
}
#Override
public int getItemCount() {
if (movieList == null)
return 0;
return movieList.size();
}
class ViewHolder extends RecyclerView.ViewHolder {
TextView name;
TextView year;
public ViewHolder(View itemView) {
super(itemView);
name = itemView.findViewById(R.id.movie_name);
year = itemView.findViewById(R.id.release_year);
itemView.setOnClickListener(new View.OnClickListener() {
#Override
public void onClick(View v) {
if(onRecyclerViewItemClickListener != null){
int position = getAdapterPosition();
if(position != RecyclerView.NO_POSITION){
onRecyclerViewItemClickListener.onRecyclerViewItemClick(position);
}
}
}
});
}
}
public interface OnRecyclerViewItemClickListener {
void onRecyclerViewItemClick(int position);
}
}
my AllMoviesFragment
public class AllMoviesFragment extends Fragment implements RecyclerViewAdapter.OnRecyclerViewItemClickListener {
private static final String CURR_MOVIE = "Current Movie";
private static final String TAG = "MSApp";
List<MovieDetails> movieList;
RecyclerView recyclerView;
public AllMoviesFragment() {
}
#Override
public View onCreateView(LayoutInflater inflater, ViewGroup container,
Bundle savedInstanceState) {
// Inflate the layout for this fragment
movieList = App.getAppInstance().getDatabaseInstance().getMovieDao().getAllMovies();
movieList.sort(new Comparator<MovieDetails>() {
#Override
public int compare(MovieDetails o1, MovieDetails o2) {
return o2.getReleaseYear() - o1.getReleaseYear();
}
});
View resultView = inflater.inflate(R.layout.fragment_all_movies, container, false);
recyclerView = resultView.findViewById(R.id.recycler_view);
RecyclerView.LayoutManager layoutManager = new LinearLayoutManager(getActivity());
recyclerView.setLayoutManager(layoutManager);
recyclerView.setHasFixedSize(true);
RecyclerViewAdapter adapter = new RecyclerViewAdapter(movieList);
adapter.setOnRecyclerViewItemClickListener(AllMoviesFragment.this);
recyclerView.setAdapter(adapter);
return resultView;
}
#Override
public void onRecyclerViewItemClick(int position) {
MovieDetails choosenMovie = movieList.get(position);
FragmentManager fragmentManager = getFragmentManager();
Fragment movieDetailsFragment = new MovieDetailsFragment();
Bundle args = new Bundle();
args.putParcelable(CURR_MOVIE, choosenMovie);
movieDetailsFragment.setArguments(args);
String tag = "MovieDetails";
FragmentTransaction transaction = fragmentManager.beginTransaction();
transaction.replace(R.id.main_container, movieDetailsFragment, tag);
transaction.addToBackStack(tag);
transaction.commit();
}
}
sorry for long post. I dont know how to cut it
I use App class for db access if it is important

#AkakiKapanadze
you was almost right
I didnot see the error message because it disappeared less 1 second
and class MovieDetailsFragment
after I remove binder of ButterKnife all work... I dont know WHY - I always use Butterknife inside Fragments

Handling onClicks of RecyclerView inside a Fragment

I am trying to implement RecyclerView inside a Fragment. I have designed a CustomAdapter(StateAdapter) class to load the contents of RecyclerView and an interface StateAdapterOnClickHandler to handle onClicks of the items inside RecyclerView but clicking on item doesn't work.
Here's my HomeFragment.java which extends Fragment. I am unable to figure out how to initialize the StateAdapterOnClickHandler and where to call its method onItemClick()
public class HomeFragment extends Fragment implements StateAdapter.StateAdapterOnClickHandler {
private View homeFragment;
private RecyclerView recyclerView;
private StateAdapter stateAdapter;
private List<String> states;
#Override
public void onCreate(#Nullable Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
}
public static HomeFragment newInstance() {
HomeFragment homeFragment = new HomeFragment();
return homeFragment;
}
#Nullable
#Override
public View onCreateView(LayoutInflater inflater, #Nullable ViewGroup container, #Nullable Bundle savedInstanceState) {
homeFragment = inflater.inflate(R.layout.fragment_home,container,false);
recyclerView = homeFragment.findViewById(R.id.recyclerview_states);
states = Arrays.asList(getResources().getStringArray(R.array.india_states));
LinearLayoutManager layoutManager = new LinearLayoutManager(container.getContext(),LinearLayoutManager.VERTICAL,false);
recyclerView.setLayoutManager(layoutManager);
recyclerView.setHasFixedSize(true);
stateAdapter = new StateAdapter();
stateAdapter.setStateNames(states);
recyclerView.setAdapter(stateAdapter);
return homeFragment;
}
#Override
public void onItemClick(String state) {
Intent intent = new Intent(getActivity(),DetailActivity.class);
intent.putExtra("State",state);
startActivity(intent);
}
}
Here's my StateAdapter class
public class StateAdapter extends RecyclerView.Adapter<StateAdapter.StateViewHolder> {
private List<String> stateNames;
private final StateAdapterOnClickHandler stateAdapterOnClickHandler;
StateAdapter(StateAdapterOnClickHandler stateAdapterOnClickHandler){
this.stateAdapterOnClickHandler = stateAdapterOnClickHandler;
}
public interface StateAdapterOnClickHandler {
void onItemClick(String state);
}
#Override
public StateAdapter.StateViewHolder onCreateViewHolder(ViewGroup parent, int viewType) {
Context context = parent.getContext();
int idForListItem = R.layout.state_layout;
LayoutInflater inflater = LayoutInflater.from(context);
View view = inflater.inflate(idForListItem,parent,false);
return new StateViewHolder(view);
}
#Override
public void onBindViewHolder(StateAdapter.StateViewHolder holder, int position) {
String stateName = stateNames.get(position);
holder.mTextView.setText(stateName);
}
#Override
public int getItemCount() {
if(stateNames == null) return 0;
return stateNames.size();
}
public class StateViewHolder extends RecyclerView.ViewHolder implements View.OnClickListener {
public final TextView mTextView;
public StateViewHolder(View itemView) {
super(itemView);
mTextView = (TextView) itemView.findViewById(R.id.tv_state_name);
itemView.setOnClickListener(this);
}
#Override
public void onClick(View v) {
int clickedPostion = getAdapterPosition();
String state = stateNames.get(clickedPostion);
stateAdapterOnClickHandler.onItemClick(state);
}
}
public void setStateNames(List<String> states) {
stateNames = states;
notifyDataSetChanged();
}
}
Please, tell me what's wrong with the code while handling the clicks. I am new to Android Programming and this is first time I am working with Fragments. Thanks for helping.

Recycle view not displaying data on the first instance

Recycle view not displaying data its shows an empty screen, It displays data when I go back and click the icon again. Not sure why I'm facing this problem.Please check the activity, adaptor and fragment code below. I'm new to android and I'm doing my capstone project it would be great if you can help me.
public class AppDetailsActivity extends AppCompatActivity {
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setTitle("App Details");
setContentView(R.layout.activity_app);
AppDetailsFragment newFragment = new AppDetailsFragment();
FragmentTransaction transaction = getSupportFragmentManager().beginTransaction();
transaction.replace(R.id.recordAppFragmentContainer, newFragment);
transaction.addToBackStack(null);
transaction.commit();
}
public void refreshAppDuration(View v) {
Intent intent = new Intent(this, AppDetailsActivity.class);
startActivity(intent);
}
protected void onPause() {
super.onPause();
}
protected void onStop() {
super.onStop();
}
protected void onDestroy() {
super.onDestroy();
}
public void onBackAppDuration(View v) {
if (getFragmentManager().getBackStackEntryCount() > 0) {
getFragmentManager().popBackStack();
} else {
super.onBackPressed();
}
}
Adaptor
public class AppDetailsAdaptor extends RecyclerView.Adapter<AppDetailsAdaptor.ViewHolder> {
private List<AppUsage> mApps;
private Context mContext;
public AppDetailsAdaptor(Context context, List<AppUsage> apps) {
mApps = apps;
mContext = context;
}
private Context getContext() {
return mContext;
}
#Override
public AppDetailsAdaptor.ViewHolder onCreateViewHolder(ViewGroup parent, int viewType) {
Context context = parent.getContext();
LayoutInflater inflater = LayoutInflater.from(context);
// Inflate the custom layout
View appUsageView = inflater.inflate(R.layout.item_app_details, parent, false);
// Return a new holder instance
AppDetailsAdaptor.ViewHolder viewHolder = new AppDetailsAdaptor.ViewHolder(appUsageView);
return viewHolder;
}
#Override
public void onBindViewHolder(AppDetailsAdaptor.ViewHolder viewHolder, final int position) {
// Get the data model based on position
final AppUsage ch = mApps.get(position);
// Set item views based on your views and data model
viewHolder._appTextView.setText(ch.getAppName());
viewHolder._durationTextView.setText(ch.getDurationInMinutes());
viewHolder._dateTextView.setText(ch.getDate().substring(0,10));
final String key = ch.getKey();
}
#Override
public int getItemCount() {
return mApps.size();
}
public class ViewHolder extends RecyclerView.ViewHolder {
public TextView _appTextView;
public TextView _durationTextView;
public TextView _dateTextView;
super(itemView);
_appTextView = (TextView) itemView.findViewById(R.id.rvs_app_name);
_durationTextView = (TextView) itemView.findViewById(R.id.rvs_app_duration);
_dateTextView =(TextView) itemView.findViewById(R.id.rvs_app_date);
}
}
}
Fragment
public class AppDetailsFragment extends Fragment {
final FirebaseDatabase database = FirebaseDatabase.getInstance();
ArrayList<AppUsage> appList = new ArrayList<>();
ArrayList<AppUsage> appListTemp = new ArrayList<>();
ArrayList<AppUsage> appListAdaptor = new ArrayList<>();
ArrayList<AppUsage> appObject = new ArrayList<>();
ArrayList<AppUsage> appListDate = new ArrayList<>();
private AppDetailsFragment.OnFragmentInteractionListener mListener;
private RecyclerView rvApp;
private RecyclerView.Adapter appAdaptor;
private RecyclerView.LayoutManager eLayoutManager;
private EditText date;
private static final int DIALOG_DATE_PICKER = 100;
#Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
}
#Override
public View onCreateView(LayoutInflater inflater, ViewGroup container,
Bundle savedInstanceState) {
View rootView = inflater.inflate(R.layout.fragment_app_list, container, false);
rvApp = (RecyclerView) rootView.findViewById(R.id.rvAppList);
rvApp.setHasFixedSize(true);
eLayoutManager = new LinearLayoutManager(getActivity());
rvApp.setLayoutManager(eLayoutManager);
appList = getAllAppRecords();
appAdaptor = new AppDetailsAdaptor(getActivity(), appList);
rvApp.setAdapter(appAdaptor);
return rootView;
}
public ArrayList<AppUsage> getAllAppRecords(){
DatabaseReference ref = database.getReference();
ref.child("AppUsage").addValueEventListener(new ValueEventListener() {
#Override
public void onDataChange(DataSnapshot dataSnapshot) {
appObject.clear();
HashMap<String,Object> app = null;
Iterator<DataSnapshot> items = dataSnapshot.getChildren().iterator();
while(items.hasNext()){
DataSnapshot item = items.next();
Log.e("Listener",item.toString() );
app =(HashMap<String, Object>) item.getValue();
appObject.add(new AppUsage(app.get("appName").toString(),app.get("durationInMinutes").toString(),app.get("date").toString(),item.getKey()));
}
}
#Override
public void onCancelled(DatabaseError databaseError) {
}
});
return appObject;
}

Error when i start fragment with recyclerview and adapter

When I start activity with fragment, recyclerview and adapter the app is stopping. I don't know where the problem is. I've tried different methods.
My logcat:
java.lang.NullPointerException: Attempt to invoke virtual method 'void
android.support.v7.widget.RecyclerView.setAdapter(android.support.v7.widget.RecyclerView$Adapter)'
on a null object reference
at com.orthodox.FeedActivity.onStart(FeedActivity.java:133)
at android.support.v4.app.Fragment.performStart(Fragment.java:2287)
My code:
public class FeedActivity extends Fragment{
private RecyclerView mBlogList;
private Query mQuery;
private Query mQueryck;
private DatabaseReference mDatabaseUsers;
private FirebaseUser mCurrent;
private FirebaseAuth mAuth;
private FirebaseAuth.AuthStateListener mAuthListener;
FirebaseRecyclerAdapter mAdapter;
public FeedActivity() {
// Required empty public constructor
}
#Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
}
#Override
public View onCreateView(LayoutInflater inflater, ViewGroup container,
Bundle savedInstanceState) {
final FragmentActivity c = getActivity();
View layout = inflater.inflate(R.layout.fragment_feed, container, false);
return layout;
}
#Override
public void onViewCreated(View view, Bundle savedInstanceState) {
mBlogList = (RecyclerView) view.findViewById(R.id.blog_list);
mBlogList.setHasFixedSize(true);
LinearLayoutManager layoutManager = new LinearLayoutManager(getActivity());
mBlogList.setLayoutManager(layoutManager);
mAuth = FirebaseAuth.getInstance();
mAuthListener = new FirebaseAuth.AuthStateListener() {
#Override
public void onAuthStateChanged(#NonNull FirebaseAuth firebaseAuth) {
if(firebaseAuth.getCurrentUser() == null){
Intent loginIntent = new Intent(getActivity(), SignUpActivity.class);
loginIntent.addFlags(Intent.FLAG_ACTIVITY_CLEAR_TOP);
startActivity(loginIntent);
}
}
};
mQuery = FirebaseDatabase.getInstance().getReference().child("Blog").limitToLast(20);
mQuery.keepSynced(true);
mQueryck = FirebaseDatabase.getInstance().getReference().child("Block").limitToLast(20);
mQueryck.keepSynced(true);
mDatabaseUsers = FirebaseDatabase.getInstance().getReference().child("users");
mDatabaseUsers.keepSynced(true);
mCurrent = mAuth.getCurrentUser();
}
#Override
public void onStart() {
super.onStart();
mAuth.addAuthStateListener(mAuthListener);
FirebaseRecyclerOptions<User> options = new FirebaseRecyclerOptions.Builder<User>().setQuery(mQuery, User.class).build();
FirebaseRecyclerOptions<User> optionss = new FirebaseRecyclerOptions.Builder<User>().setQuery(mQueryck, User.class).build();
mAdapter = new FirebaseRecyclerAdapter<User, BlogViewHolder>(options) {
#Override
public BlogViewHolder onCreateViewHolder(ViewGroup parent, int viewType) {
// Create a new instance of the ViewHolder
View view = LayoutInflater.from(parent.getContext()).inflate(R.layout.blog_row, parent, false);
return new BlogViewHolder(view);
}
#Override
protected void onBindViewHolder(BlogViewHolder viewHolder, int position, User model) {
final String post_key = getRef(position).getKey();
viewHolder.setTitle(model.getTitle());
viewHolder.setDesc(model.getDesc());
viewHolder.setTime(model.getFirstname());
viewHolder.setImage(getApplicationContext(), model.getImage());
}
};
mBlogList.setAdapter(mAdapter);
mAdapter.startListening();
mAdapter = new FirebaseRecyclerAdapter<User, BlogViewHolder>(optionss) {
#Override
protected void onBindViewHolder(BlogViewHolder viewHolder, int position, User model) {
final String post_key = getRef(position).getKey();
viewHolder.setTitle(model.getTitle());
viewHolder.setDesc(model.getDesc());
viewHolder.setTime(model.getFirstname());
viewHolder.setImage(getApplicationContext(), model.getImage());
viewHolder.mView.setOnClickListener(new View.OnClickListener() {
#Override
public void onClick(View view) {
Intent bsingle = new Intent(getActivity(), SinglePostActivity.class);
bsingle.putExtra("post", post_key);
startActivity(bsingle);
}
});
}
#Override
public BlogViewHolder onCreateViewHolder(ViewGroup parent, int viewType) {
View view = LayoutInflater.from(parent.getContext()).inflate(R.layout.blog_row, parent, false);
return new BlogViewHolder(view);
}
};
}
public static class BlogViewHolder extends RecyclerView.ViewHolder {
View mView;
public BlogViewHolder(View itemView) {
super(itemView);
mView = itemView;
}
public void setTitle(String title){
TextView post_title = (TextView) mView.findViewById(R.id.post_title);
post_title.setText(title);
}
public void setDesc(String desc){
TextView post_desc = (TextView) mView.findViewById(R.id.post_desc);
post_desc.setText(desc);
}
public void setImage(Context ctx, String image){
if (image != null) {
ImageView post_image = (ImageView) mView.findViewById(R.id.post_image);
Picasso.with(ctx).load(image).into(post_image);
}
else {
ImageView post_image = (ImageView) mView.findViewById(R.id.post_image);
post_image.setVisibility(View.GONE);
}
}
public void setTime(String time){
TextView post_time = (TextView) mView.findViewById(R.id.post_username);
post_time.setText(time);
}

Initialize your all views in onCreateView method.
#Override
public View onCreateView(LayoutInflater inflater, ViewGroup container,
Bundle savedInstanceState) {
final FragmentActivity c = getActivity();
View layout = inflater.inflate(R.layout.fragment_feed, container, false);
mBlogList = (RecyclerView) layout.findViewById(R.id.blog_list);
return layout;
}