Related
In my app, I use a Contacts database and display those contacts using a RecyclerView . When I click on a contact, I want to fetch its data from the tables in the DB, and load them in a new Activity, ContactCard. I have an AsyncTask() which fetches the PhoneNumber objects that match the selected contactId, but I will also need to retrieve the Address and Email objects from the other tables.
I would like to be able to start the activity after all the relevant data is fetched, and I tried doing this in the activity with the Contacts RecyclerView, but the application crashes as the data has not been fetched yet.
I can call the new activity using an intent, but how can I ensure data from different tables is fetched first, before I start the new activity (which effectively displays this data)?
Some of my code:
public class PhoneNumberRepository {
private WorksideDatabase worksideDatabase;
private List<PhoneNumber> returnedNumbers;
private Context mContext;
public PhoneNumberRepository(Context context) {
String DB_NAME = "workside_database";
worksideDatabase = Room.databaseBuilder(context, WorksideDatabase.class, DB_NAME).build();
mContext = context;
}
public List<PhoneNumber> fetchPhoneNumbers(final int id) {
new AsyncTask<Integer, Void, List<PhoneNumber>>() {
#Override
protected List<PhoneNumber> doInBackground(Integer... ids) {
returnedNumbers = worksideDatabase.phoneNumberDao().getPhoneNumbersById(id);
System.out.println(returnedNumbers);
for (PhoneNumber pn : returnedNumbers) {
System.out.println("Number: " + pn.getPhoneNumber());
}
return returnedNumbers;
}
// This runs in UI when background thread finishes
#Override
protected void onPostExecute(List<PhoneNumber> result) {
super.onPostExecute(result);
System.out.println("Entered onPostExecute of fetchPhoneNumbers");
// for (PhoneNumber pn : result) {
// Toast.makeText(mContext, pn + "", Toast.LENGTH_SHORT).show();
// }
}
}.execute();
return returnedNumbers;
}
public List<PhoneNumber> getPhoneNumbers(int id) {
return fetchPhoneNumbers(id);
}
}
ContactsFragment:
adapter.setOnItemClickListener(
contact -> {
Intent viewContact = new Intent(getActivity(), WorksideContactCard.class);
viewContact.putExtra(WORKSIDE_CONTACT, contact);
PhoneNumberRepository phoneNumberRepository =
new PhoneNumberRepository(getActivity().getApplicationContext());
List<PhoneNumber> phoneNumberList;
phoneNumberList = phoneNumberRepository.getPhoneNumbers(contact.getId());
ArrayList<PhoneNumber> arrlistPhoneNumbers =
new ArrayList<>(phoneNumberList);
viewContact.putParcelableArrayListExtra(
WORKSIDE_CONTACT_PHONE_NO, arrlistPhoneNumbers);
startActivity(viewContact);
}
You can do this when you click on an item start the asyntask like this
adapter.setOnItemClickListener(
contact -> {
PhoneNumberRepository phoneNumberRepository =
new PhoneNumberRepository(getActivity().getApplicationContext());
List<PhoneNumber> phoneNumberList;
phoneNumberRepository.getPhoneNumbers(contact.getId());
}
and change your PhoneNumberRepository to this class
public class PhoneNumberRepository {
private WorksideDatabase worksideDatabase;
private List<PhoneNumber> returnedNumbers;
private Context mContext;
public PhoneNumberRepository(Context context) {
String DB_NAME = "workside_database";
worksideDatabase = Room.databaseBuilder(context, WorksideDatabase.class, DB_NAME).build();
mContext = context;
}
public void fetchPhoneNumbers(final int id) {
new AsyncTask<Integer, Void, List<PhoneNumber>>() {
#Override
protected List<PhoneNumber> doInBackground(Integer... ids) {
returnedNumbers = worksideDatabase.phoneNumberDao().getPhoneNumbersById(id);
System.out.println(returnedNumbers);
for (PhoneNumber pn : returnedNumbers) {
System.out.println("Number: " + pn.getPhoneNumber());
}
return returnedNumbers;
}
// This runs in UI when background thread finishes
#Override
protected void onPostExecute(List<PhoneNumber> result) {
super.onPostExecute(result);
Intent viewContact = new Intent(context, WorksideContactCard.class);
ArrayList<PhoneNumber> arrlistPhoneNumbers =
new ArrayList<>(result);
viewContact.putParcelableArrayListExtra(
WORKSIDE_CONTACT_PHONE_NO, arrlistPhoneNumbers);
context.startActivity(viewContact);
System.out.println("Entered onPostExecute of fetchPhoneNumbers");
}
}.execute();
}
public void getPhoneNumbers(int id) {
return fetchPhoneNumbers(id);
}
}
store the contacts in a list in the doInBackground() method and start an intent to the new activity in the onPostExecute() method and with this intent pass the list of contacts as intent.extra() variables, retrieve and use them in the called activity.
Change your repository class to something like this
public class PhoneNumberRepository {
private WorksideDatabase worksideDatabase;
private List<PhoneNumber> returnedNumbers;
private Context mContext;
private boolean dataDownloaded;
public PhoneNumberRepository(Context context) {
String DB_NAME = "workside_database";
worksideDatabase = Room.databaseBuilder(context, WorksideDatabase.class, DB_NAME).build();
mContext = context;
}
public List<PhoneNumber> fetchPhoneNumbers(final int id) {
new AsyncTask<Integer, Void, List<PhoneNumber>>() {
#Override
protected List<PhoneNumber> doInBackground(Integer... ids) {
returnedNumbers = worksideDatabase.phoneNumberDao().getPhoneNumbersById(id);
System.out.println(returnedNumbers);
for (PhoneNumber pn : returnedNumbers) {
System.out.println("Number: " + pn.getPhoneNumber());
}
return returnedNumbers;
}
// This runs in UI when background thread finishes
#Override
protected void onPreExecute(List<PhoneNumber> result) {
//set flag to false when download starts
dataDownloaded = false;
}
// This runs in UI when background thread finishes
#Override
protected void onPostExecute(Object obj) {
super.onPostExecute(result);
//set flag to true once download completes, you can also check if response is null and update it accordingly
dataDownloaded = true;
System.out.println("Entered onPostExecute of fetchPhoneNumbers");
// for (PhoneNumber pn : result) {
// Toast.makeText(mContext, pn + "", Toast.LENGTH_SHORT).show();
// }
}
}.execute();
return returnedNumbers;
}
public List<PhoneNumber> getPhoneNumbers(int id) {
return fetchPhoneNumbers(id);
}
public boolean isDataDownloaded(int id) {
return dataDownloaded;
}
}
Use this function in onItemClick() whether your data is downloaded or not
if(phoneNumberRepository.isDataDownloaded()) {
//code to fetch data from phonenumberrepo and start activity
}
I am making an attendance system where I take the attendance using RadioGroup with two options. When I select some radio button and scroll down some other radio button gets auto-selected. If I change them upper ones also get changed.
Main class
public class TeacherAttendanceActivity extends AppCompatActivity implements AttendanceAdapter.AttendanceAdapterListner {
public static TeacherAttendanceActivity teacherAttendanceActivity;
private static final String TAG = TeacherAttendanceActivity.class.getSimpleName();
List<AttendanceModel> listItems;
private RecyclerView recyclerView;
private RecyclerView.Adapter adapter;
private AttendanceAdapter attendanceAdapter;
ProgressDialog progressDialog;
private SQLiteHandler db;
private SessionManager session;
private SearchView searchView;
Button btnSubmit;
JSONObject mainObj = new JSONObject();
// date
SimpleDateFormat sdf = new SimpleDateFormat("yyyy-MM-dd");
String currentDateandTime = sdf.format(new Date());
String class_id,title;
Boolean Error;
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_teacher_attendance);
//get data from intent
class_id = super.getIntent().getExtras().getString("id"); //class_id
title = super.getIntent().getExtras().getString("title");
getSupportActionBar().setTitle("Class: "+title+", Date: "+currentDateandTime );
// SqLite database handler
db = new SQLiteHandler(getApplicationContext());
// session manager
session = new SessionManager(getApplicationContext());
btnSubmit=findViewById(R.id.buttonAttendanceSubmit);
btnSubmit.setOnClickListener(new View.OnClickListener() {
#Override
public void onClick(View v) {
Error=false;
Gson gson=new Gson();
final String newDataArray=gson.toJson(listItems); // dataarray is list aaray
for (int i = 0; i < AttendanceAdapter.listItems.size(); i++){
if(AttendanceAdapter.listItems.get(i).getAttendance()==null){
Toast.makeText(TeacherAttendanceActivity.this, "Check attendance at roll:"+AttendanceAdapter.listItems.get(i).getRoll(), Toast.LENGTH_SHORT).show();
Error =true;
break;
}
}
if (!Error){
request(class_id,currentDateandTime,newDataArray);
}
}
});
listItems = new ArrayList<>();
attendanceAdapter = new AttendanceAdapter(listItems, this, (AttendanceAdapter.AttendanceAdapterListner) this);
recyclerView = (RecyclerView) findViewById(R.id.list_attendance);
recyclerView.setLayoutManager(new LinearLayoutManager(TeacherAttendanceActivity.this));
progressDialog = new ProgressDialog(this);
teacherAttendanceActivity = this;
//refresh_list(class_id);
}
#Override
protected void onStart() {
refresh_list(class_id);
super.onStart();
}
#Override
public void onAttendanceAdapterSelected(AttendanceModel model) {
}
#Override
public boolean onCreateOptionsMenu(Menu menu) {
// Inflate the menu; this adds items to the action bar if it is present.
getMenuInflater().inflate(R.menu.refresh, menu);
getMenuInflater().inflate(R.menu.tool_bar, menu);
return true;
}
#Override
public boolean onOptionsItemSelected(MenuItem item) {
int id = item.getItemId();
switch (id){
case R.id.action_settings:
Toast.makeText(getApplicationContext(),"Sittings",Toast.LENGTH_LONG).show();
return true;
case R.id.action_logout:
logoutUser();
return true;
case R.id.action_about:
Toast.makeText(getApplicationContext(),"About",Toast.LENGTH_LONG).show();
return true;
case R.id.action_devinfo:
Toast.makeText(getApplicationContext(),"Dev info",Toast.LENGTH_LONG).show();
return true;
case R.id.refresh:
refresh_list(class_id);
return true;
default:
return super.onOptionsItemSelected(item);
}
}
void logoutUser() {
session.setLogin(false);
db.deleteUsers();
// Launching the login activity
Intent intent = new Intent(this, MainActivity.class);
startActivity(intent);
finish();
}
// refresh list
public void refresh_list(String id) {
// this method refresh list and get the json data
listItems.clear();
// adapter = new MyAdapter(listItems,getApplicationContext());
recyclerView.setAdapter(attendanceAdapter);
recyclerView.setItemAnimator(new DefaultItemAnimator());
progressDialog.setMessage("Loading");
progressDialog.show();
StringRequest stringRequest = new StringRequest(Request.Method.GET, ApiConfig.URL_TEACHER_ATTENDANCE+id, new Response.Listener<String>() {
#Override
public void onResponse(String response) {
progressDialog.dismiss();
try {
progressDialog.hide();
JSONObject jsonObject = new JSONObject(response);
JSONArray jsonArray = jsonObject.getJSONArray("Data"); // finding data
Log.d(TAG, String.valueOf(jsonObject));
int len = jsonArray.length();
for (int i = 0; i < len; i++) {
JSONObject o = jsonArray.getJSONObject(i);
AttendanceModel item = new AttendanceModel(
o.getString("id"),
o.getString("name"),
o.getString("roll"),
o.getString("class_id"),
o.getString("status"),
null
);
listItems.add(item);
//adapter = new MyAdapter(listItems,getApplicationContext());
recyclerView.setAdapter(attendanceAdapter); // setting them in list view
}
} catch (JSONException e) {
e.printStackTrace();
}
}
}, new Response.ErrorListener() {
#Override
public void onErrorResponse(VolleyError error) {
progressDialog.hide();
Toast.makeText(TeacherAttendanceActivity.this, "Failed", Toast.LENGTH_SHORT).show();
}
}) {
/** Passing some request headers* */
#Override
public Map getHeaders() throws AuthFailureError {
SQLiteHandler db = new SQLiteHandler(getApplicationContext());
HashMap<String,String> userDetail= db.getUserDetails();
String userToken = userDetail.get("token");
Log.d(TAG, String.valueOf(userToken));
HashMap headers = new HashMap();
headers.put("Accept", "application/json");
headers.put("Authorization", "Bearer "+userToken);
return headers;
}
};
stringRequest.setShouldCache(false);
VolleyRequest.getInstance(TeacherAttendanceActivity.this).addToRequestQueue(stringRequest);
}
// take attendance
private void request( final String classId,final String date,final String data ) {
progressDialog.setMessage("Taking attendance");
showDialog();
StringRequest strReq = new StringRequest(Request.Method.POST,
ApiConfig.URL_TEACHER_ATTENDANCE_STORE, new Response.Listener<String>() {
#Override
public void onResponse(String response) {
Log.d(TAG, "Login Response: " + response);
hideDialog();
try {
JSONObject jObj = new JSONObject(response);
boolean error = jObj.getBoolean("error");
// Check for error node in json
if (!error) {
String attendance = jObj.getString("Attendance");
Toast.makeText(TeacherAttendanceActivity.this, attendance, Toast.LENGTH_LONG).show();
finish();
} else {
// Error in login. Get the error message
String errorMsg = jObj.getString("message");
Toast.makeText(TeacherAttendanceActivity.this,
errorMsg, Toast.LENGTH_LONG).show();
}
} catch (JSONException e) {
// JSON error
e.printStackTrace();
Toast.makeText(TeacherAttendanceActivity.this, "Json error: " + e.getMessage(), Toast.LENGTH_LONG).show();
}
}
}, new Response.ErrorListener() {
#Override
public void onErrorResponse(VolleyError error) {
Log.e(TAG, "Login Error: " + error.getMessage());
Toast.makeText(TeacherAttendanceActivity.this,
error.getMessage(), Toast.LENGTH_LONG).show();
hideDialog();
}
}) {
/** Passing some request headers* */
#Override
public Map getHeaders() throws AuthFailureError {
SQLiteHandler db = new SQLiteHandler(TeacherAttendanceActivity.this);
HashMap<String,String> userDetail= db.getUserDetails();
String userToken = userDetail.get("token");
Log.d(TAG, String.valueOf(userToken));
HashMap headers = new HashMap();
headers.put("Accept", "application/json");
headers.put("Authorization", "Bearer "+userToken);
return headers;
}
#Override
protected Map<String, String> getParams() {
// Posting parameters to login url
Map<String, String> params = new HashMap<String, String>();
params.put("class_id", classId);
params.put("date", date);
params.put("data", data);
return params;
}
};
strReq.setShouldCache(false);
// Adding request to request queue
VolleyRequest.getInstance(TeacherAttendanceActivity.this).addToRequestQueue(strReq);
}
private void showDialog() {
if (!progressDialog.isShowing())
progressDialog.show();
}
private void hideDialog() {
if (progressDialog.isShowing())
progressDialog.dismiss();
}
}
Model class
'model class for convenient '
public class AttendanceModel {
String id,name,roll,classId,previousAttendance,attendance;
public AttendanceModel(String id, String name,String roll, String classId,String previousAttendance,String attedance ){
this.id = id;
this.name = name;
this.classId =classId;
this.roll=roll;
this.attendance=attedance;
this.previousAttendance=previousAttendance;
}
public String getAttendance() {
return attendance;
}
public String getId() {
return id;
}
public String getName() {
return name;
}
public String getRoll() {
return roll;
}
public String getClassId() {
return classId;
}
public String getPreviousAttendance(){return previousAttendance;}
public void setId(String id) {
this.id = id;
}
public void setName(String name) {
this.name = name;
}
public void setRoll(String roll) {
this.roll = roll;
}
public void setClassId(String classId) {
this.classId = classId;
}
public void setPreviousAttendance(String previousAttendance) {
this.previousAttendance = previousAttendance;
}
public void setAttendance(String attendance) {
this.attendance = attendance;
}
}
Adapter class
' adapter class '
public class AttendanceAdapter extends RecyclerView.Adapter<AttendanceAdapter.ViewHolder> implements Filterable
{
// date
SimpleDateFormat sdf = new SimpleDateFormat("yyyy-MM-dd");
String currentDateandTime = sdf.format(new Date());
private static final String TAG = AttendanceAdapter.class.getSimpleName();
public static List<AttendanceModel> listItems;
private List<AttendanceModel> listItemsFiltered;
private Context context;
private ProgressDialog dialog;
private AttendanceAdapter.AttendanceAdapterListner listner;
private ProgressDialog pDialog;
private SQLiteHandler db;
public static JSONObject jo = new JSONObject();
public static JSONArray ja = new JSONArray();
public AttendanceAdapter(List<AttendanceModel> listItems, Context context, AttendanceAdapter.AttendanceAdapterListner listner) {
this.listItems = listItems;
this.listner=listner;
this.context = context;
this.listItemsFiltered =listItems;
// SqLite database handler
db = new SQLiteHandler(context);
// Progress dialog
pDialog = new ProgressDialog(context);
}
#Override
public Filter getFilter() {
return new Filter() {
#Override
protected FilterResults performFiltering(CharSequence charSequence) {
String charString = charSequence.toString();
if (charString.isEmpty()) {
listItemsFiltered = listItems;
} else {
List<AttendanceModel> filteredList = new ArrayList<>();
for (AttendanceModel row : listItems) {
// name match condition. this might differ depending on your requirement
// here we are looking for name or phone number match
if (row.getName().toUpperCase().contains(charSequence.toString().toUpperCase())||row.getName().toLowerCase().contains(charSequence.toString().toLowerCase())) {
filteredList.add(row);
}
}
listItemsFiltered = filteredList;
}
FilterResults filterResults = new FilterResults();
filterResults.values = listItemsFiltered;
return filterResults;
}
#Override
protected void publishResults(CharSequence charSequence, FilterResults filterResults) {
listItemsFiltered = (ArrayList<AttendanceModel>) filterResults.values;
notifyDataSetChanged();
}
};
}
public class ViewHolder extends RecyclerView.ViewHolder {
public TextView name;
public TextView roll;
public TextView previous;
RadioGroup radioAttendance;
RadioButton radioAttendancePresent,radioAttendanceAbsent;
public CardView card_view;
public ViewHolder(View itemView) {
super(itemView);
name= (TextView) itemView.findViewById(R.id.textViewAttendanceStudentName);
roll = (TextView) itemView.findViewById(R.id.textViewAttendanceStudentRoll);
previous = (TextView) itemView.findViewById(R.id.textViewAttendanceStudentPreviousStatus);
radioAttendance = itemView.findViewById(R.id.radioAttendance);
radioAttendancePresent =itemView.findViewById(R.id.radioAttendancePresent);
radioAttendanceAbsent =itemView.findViewById(R.id.radioAttendanceAbsent);
//card_view = (CardView) itemView.findViewById(R.id.class_card_view); // card view for on click method
itemView.setOnClickListener(new View.OnClickListener() {
#Override
public void onClick( View view) {
// send selected contact in callback
listner.onAttendanceAdapterSelected(listItemsFiltered.get(getAdapterPosition())); // selecting cardview and position (model)
}
});
radioAttendance.setOnCheckedChangeListener(new RadioGroup.OnCheckedChangeListener() {
#Override
public void onCheckedChanged(RadioGroup radioGroup, int i) {
//Toast.makeText(TeacherAttendanceActivity.this, toString(i), Toast.LENGTH_SHORT).show();
// Toast.makeText(context,"clicked at position"+i+" "+id+""+name,Toast.LENGTH_SHORT).show();
if(radioAttendancePresent.isChecked())
{
listItems.get(getAdapterPosition()).setAttendance("present");
}
else {
listItems.get(getAdapterPosition()).setAttendance("absent");
}
}
});
}
}
#Override
public AttendanceAdapter.ViewHolder onCreateViewHolder(ViewGroup parent, int viewType) {
View v = LayoutInflater.from(parent.getContext()).inflate(R.layout.attendance_list, parent, false);
return new AttendanceAdapter.ViewHolder(v);
}
#Override
public void onBindViewHolder (final AttendanceAdapter.ViewHolder holder, final int position) {
final AttendanceModel listItem = listItemsFiltered.get(position);
holder.name.setText(listItem.getName());
holder.roll.setText(listItem.getRoll());
holder.previous.setText(listItem.getPreviousAttendance());
}
public interface AttendanceAdapterListner {
void onAttendanceAdapterSelected(AttendanceModel model); // sending cardview to say the dialoge and model for sending context
}
#Override
public int getItemCount() {
return listItemsFiltered.size();
}
private void showDialog() {
if (!pDialog.isShowing())
pDialog.show();
}
private void hideDialog() {
if (pDialog.isShowing())
pDialog.dismiss();
}
}
Your problem would be solved by making small changes to your Recycler view adapter, please do not disable recyclable property, this makes your recycler view a glorified list view.
I can see you tried using a sparse boolean array to hold the state of the radio buttons, that is good but you do not need that too. The idea behind using a Sparse boolean array is to keep the state of each item in the recycler view so that when they are recycled you still have a reference to what the state of each item is.
In your adapter you already have something that we can use to know the state, that is the attendance property of your model, in that case, you can set the state of your checkboxes by checking if the attendance property is present or absent.
One more thing about your code is that you are using the onCheckChangedListener as a click event handler for your radio button, you should not use this because it responds to all check changed events, even if it is triggered from code and not from user action, so when you bind your view and you set any of your radio buttons as checked or unchecked, it calls this callback.
Here is a modified version of your ViewHolder class that solves this issue by applying the solution above.
public class ViewHolder extends RecyclerView.ViewHolder {
public TextView name;
public TextView roll;
public TextView previous;
RadioGroup radioAttendance;
RadioButton radioAttendancePresent, radioAttendanceAbsent;
public CardView card_view;
public ViewHolder(View itemView) {
super(itemView);
name = (TextView) itemView.findViewById(R.id.textViewAttendanceStudentName);
roll = (TextView) itemView.findViewById(R.id.textViewAttendanceStudentRoll);
previous = (TextView) itemView.findViewById(R.id.textViewAttendanceStudentPreviousStatus);
radioAttendance = itemView.findViewById(R.id.radioAttendance);
radioAttendancePresent = itemView.findViewById(R.id.radioAttendancePresent);
radioAttendanceAbsent = itemView.findViewById(R.id.radioAttendanceAbsent);
radioAttendancePresent.setOnClickListener(new View.OnClickListener() {
#Override
public void onClick(View v) {
radioAttendancePresent.setChecked(true);
listItems.get(getAdapterPosition()).setAttendance("present");
}
});
radioAttendanceAbsent.setOnClickListener(new View.OnClickListener() {
#Override
public void onClick(View v) {
radioAttendanceAbsent.setChecked(true);
listItems.get(getAdapterPosition()).setAttendance("absent");
}
});
}
void bind(int position) {
// use the sparse boolean array to check
if (listItems.get(position).getAttendance() != null) {
if (listItems.get(position).getAttendance().equals("present")) {
radioAttendancePresent.setChecked(true);
} else if (listItems.get(position).getAttendance().equals("absent")) {
radioAttendanceAbsent.setChecked(true);
}
} else {
radioAttendance.clearCheck();
}
name.setText(listItems.get(position).getName());
roll.setText(listItems.get(position).getRoll());
previous.setText(listItems.get(position).getPreviousAttendance());
}
}
Notice that we have separate click listener for each radio button and set the state in the list of items and just check that state when we are binding, also we have removed the onCheckChangedListener and the sparse boolean array, one last thing is that we made sure that when there is not state set for the attendance property, we just clear the radio buttons so that no one is selected the code is much simpler and works correctly now.
You have to initialize your RadioButton based on model state like below:
#Override
public void onBindViewHolder (final AttendanceAdapter.ViewHolder holder, final int position) {
final AttendanceModel listItem = listItemsFiltered.get(position);
holder.name.setText(listItem.getName());
holder.roll.setText(listItem.getRoll());
holder.previous.setText(listItem.getPreviousAttendance());
final String id =listItem.getId();
final String class_id =listItem.getClassId();
holder.radioAttendance.setOnCheckedChangeListener(null);
if(listItem.getAttendance().equalsIgnoreCase("present")) {
radioAttendancePresent.setChecked(true);
} else {
radioAttendancePresent.setChecked(false);
}
//Add listener here and remove from holder
holder.radioAttendance.setOnCheckedChangeListener(new RadioGroup.OnCheckedChangeListener() {
#Override
public void onCheckedChanged(RadioGroup radioGroup, int i) {
if(holder.radioAttendancePresent.isChecked()) {
listItemsFiltered.get(position).setAttendance("present");
} else {
listItemsFiltered.get(position).setAttendance("absent");
}
notifyDataSetChanged();
}
});
}
I have 5 fragments inside my activity where one fragment stays active at one time. Clicking on a recyclerview item opens another fragment and puts current fragment in the backstack.
The same code was working fine some days ago, but now the app is throwing NotSerializableException whenever I click the home button to put the app in background. I have tried putting the initializing the variables inside onStart and then giving the null value in onStop but that didn't work.
Fragment Code:
public class PaperListFragment extends Fragment implements Serializable {
private static final String TAG = "PaperListFragment";
private static final String QUESTIONS_FRAGMENT_TAG = "questions_fragment";
private static final String ADD_PAPER_FRAGMENT_TAG = "add_paper_fragment";
private OnFragmentActiveListener mOnFragmentActiveListener;
private TextView mHeadingText;
private Bundle mOutState;
private FirebaseAuth mAuth;
private DatabaseReference mDatabaseReference;
private ProgressBar mProgressBar;
private OnItemClickListener mOnItemClickListener;
private FloatingActionButton mFab;
private RecyclerView mRecyclerViewPaper;
private ArrayList<Paper> mPaperList = new ArrayList<>();
private Subject mSubject = new Subject();
private Exam mExam = new Exam();
#Nullable
#Override
public View onCreateView(#NonNull LayoutInflater inflater, #Nullable ViewGroup container, #Nullable Bundle savedInstanceState) {
View rootView = inflater.inflate(R.layout.fragment_recycler_list, container, false);
mProgressBar = (ProgressBar) rootView.findViewById(R.id.progressbar_news);
mFab = (FloatingActionButton) rootView.findViewById(R.id.floatingActionButton);
mProgressBar.setVisibility(View.VISIBLE);
Log.d(TAG, "onCreateView: Fragment created");
mAuth = FirebaseAuth.getInstance();
mDatabaseReference = FirebaseDatabase.getInstance().getReference();
if (mAuth.getCurrentUser() == null) {
startActivity(new Intent(getActivity(), LoginActivity.class));
getActivity().finish();
return null;
}
if (getArguments() != null) {
mOnFragmentActiveListener = (OnFragmentActiveListener) getArguments().getSerializable(Keys.FRAGMENT_ACTIVE_LISTENER);
mSubject = (Subject) getArguments().getSerializable(Keys.SUBJECT_KEY);
mExam = (Exam) getArguments().getSerializable(Keys.EXAMS_KEY);
}
mRecyclerViewPaper = (RecyclerView) rootView.findViewById(R.id.recycler_list);
LinearLayoutManager layoutManager = new LinearLayoutManager(getActivity()) {
#Override
public boolean canScrollVertically() {
return false;
}
};
mRecyclerViewPaper.setLayoutManager(layoutManager);
Log.d(TAG, "onCreateView: Layout Manager Set.");
mFab.setOnClickListener(new View.OnClickListener() {
#Override
public void onClick(View view) {
startAddPaperFragment();
}
});
mOnItemClickListener = new OnItemClickListener() {
#Override
public void onItemClicked(RecyclerView.ViewHolder holder, int position) {
Log.d(TAG, "onItemClicked: Clicked item position is: "+ position);
QuestionListFragment questionFragment = new QuestionListFragment();
questionFragment.setRetainInstance(true);
startFragment(position, questionFragment, QUESTIONS_FRAGMENT_TAG);
}
#Override
public void OnItemLongClicked(RecyclerView.ViewHolder holder, int position) {
}
};
mHeadingText = (TextView) rootView.findViewById(R.id.heading_textview);
mHeadingText.setText(mExam.getExam_name()+" > "+ mSubject.getSubject_name());
if (mOutState != null) {
mPaperList = (ArrayList<Paper>) mOutState.getSerializable(Keys.PAPER_LIST_KEY);
updateUI();
} else {
updateUIFromDatabase();
}
return rootView;
}
private void startFragment(int position, Fragment fragment, String fragmentTag) {
Paper paper = new Paper();
if (mPaperList.size() > 0) {
paper = mPaperList.get(position);
}
Bundle args = new Bundle();
args.putSerializable(Keys.EXAMS_KEY, mExam);
args.putSerializable(Keys.SUBJECT_KEY, mSubject);
args.putSerializable(Keys.PAPER, paper);
args.putSerializable(Keys.FRAGMENT_ACTIVE_LISTENER, mOnFragmentActiveListener);
fragment.setArguments(args);
FragmentTransaction fragmentTransaction = getActivity().getSupportFragmentManager().beginTransaction();
fragmentTransaction.setCustomAnimations(R.anim.slide_in_right, R.anim.slide_out_left, R.anim.slide_in_left, R.anim.slide_out_right);
fragmentTransaction.replace(R.id.questions_fragment_container, fragment, fragmentTag);
fragmentTransaction.addToBackStack(fragmentTag);
fragmentTransaction.commit();
}
private void startAddPaperFragment() {
AddPaperFragment addPaperFragment = new AddPaperFragment();
addPaperFragment.setRetainInstance(true);
startFragment(0, addPaperFragment, ADD_PAPER_FRAGMENT_TAG);
}
private void updateUIFromDatabase() {
if (getArguments() != null){
Exam exam = (Exam) getArguments().getSerializable(Keys.EXAMS_KEY);
Subject subject = (Subject) getArguments().getSerializable(Keys.SUBJECT_KEY);
DatabaseReference paperReference =
mDatabaseReference
.child(Keys.APP_DATA_KEY)
.child(Keys.EXAM_PAPERS)
.child(exam.getExam_name())
.child(subject.getSubject_name());
Query query = paperReference.orderByChild(Keys.TIME_ADDED);
query.addValueEventListener(new ValueEventListener() {
#Override
public void onDataChange(#NonNull DataSnapshot dataSnapshot) {
mPaperList.clear();
for (DataSnapshot paperChild : dataSnapshot.getChildren()) {
mPaperList.add(paperChild.getValue(Paper.class));
}
updateUI();
}
#Override
public void onCancelled(#NonNull DatabaseError databaseError) {
}
});
}
}
private void updateUI() {
PaperRecyclerAdapter adapter = new PaperRecyclerAdapter(
getActivity(),
mRecyclerViewPaper,
mPaperList,
mOnItemClickListener
);
mRecyclerViewPaper.setAdapter(adapter);
mProgressBar.setVisibility(View.GONE);
}
#Override
public void onResume() {
super.onResume();
if (getArguments()!=null){
mOnFragmentActiveListener.onFragmentActive(
this,
"Topics"
);
}
}
#Override
public void onPause() {
super.onPause();
mOutState = new Bundle();
mOutState.putSerializable(Keys.PAPER_LIST_KEY, mPaperList);
}
}
Exception:
2018-12-26 17:49:38.344 14834-14834/in.crazybytes.bankmaniaadmin E/AndroidRuntime: FATAL EXCEPTION: main
Process: in.crazybytes.bankmaniaadmin, PID: 14834
java.lang.RuntimeException: Parcelable encountered IOException writing serializable object (name = in.crazybytes.bankmaniaadmin.activities.QuestionsActivity)
at android.os.Parcel.writeSerializable(Parcel.java:1526)
at android.os.Parcel.writeValue(Parcel.java:1474)
at android.os.Parcel.writeArrayMapInternal(Parcel.java:723)
at android.os.BaseBundle.writeToParcelInner(BaseBundle.java:1408)
at android.os.Bundle.writeToParcel(Bundle.java:1133)
at android.os.Parcel.writeBundle(Parcel.java:763)
at android.support.v4.app.FragmentState.writeToParcel(FragmentState.java:124)
at android.os.Parcel.writeTypedArray(Parcel.java:1306)
at android.support.v4.app.FragmentManagerState.writeToParcel(FragmentManager.java:639)
at android.os.Parcel.writeParcelable(Parcel.java:1495)
at android.os.Parcel.writeValue(Parcel.java:1401)
at android.os.Parcel.writeArrayMapInternal(Parcel.java:723)
at android.os.BaseBundle.writeToParcelInner(BaseBundle.java:1408)
at android.os.Bundle.writeToParcel(Bundle.java:1133)
at android.os.Parcel.writeBundle(Parcel.java:763)
at android.app.ActivityManagerProxy.activityStopped(ActivityManagerNative.java:3697)
at android.app.ActivityThread$StopInfo.run(ActivityThread.java:3768)
at android.os.Handler.handleCallback(Handler.java:751)
at android.os.Handler.dispatchMessage(Handler.java:95)
at android.os.Looper.loop(Looper.java:154)
at android.app.ActivityThread.main(ActivityThread.java:6123)
at java.lang.reflect.Method.invoke(Native Method)
at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:867)
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:757)
Caused by: java.io.NotSerializableException: com.google.firebase.auth.internal.zzj
at java.io.ObjectOutputStream.writeObject0(ObjectOutputStream.java:1224)
at java.io.ObjectOutputStream.defaultWriteFields(ObjectOutputStream.java:1584)
at java.io.ObjectOutputStream.writeSerialData(ObjectOutputStream.java:1549)
at java.io.ObjectOutputStream.writeOrdinaryObject(ObjectOutputStream.java:1472)
at java.io.ObjectOutputStream.writeObject0(ObjectOutputStream.java:1218)
at java.io.ObjectOutputStream.defaultWriteFields(ObjectOutputStream.java:1584)
at java.io.ObjectOutputStream.writeSerialData(ObjectOutputStream.java:1549)
at java.io.ObjectOutputStream.writeOrdinaryObject(ObjectOutputStream.java:1472)
at java.io.ObjectOutputStream.writeObject0(ObjectOutputStream.java:1218)
at java.io.ObjectOutputStream.writeObject(ObjectOutputStream.java:346)
at android.os.Parcel.writeSerializable(Parcel.java:1521)
at android.os.Parcel.writeValue(Parcel.java:1474)
at android.os.Parcel.writeArrayMapInternal(Parcel.java:723)
at android.os.BaseBundle.writeToParcelInner(BaseBundle.java:1408)
at android.os.Bundle.writeToParcel(Bundle.java:1133)
at android.os.Parcel.writeBundle(Parcel.java:763)
at android.support.v4.app.FragmentState.writeToParcel(FragmentState.java:124)
at android.os.Parcel.writeTypedArray(Parcel.java:1306)
at android.support.v4.app.FragmentManagerState.writeToParcel(FragmentManager.java:639)
at android.os.Parcel.writeParcelable(Parcel.java:1495)
at android.os.Parcel.writeValue(Parcel.java:1401)
at android.os.Parcel.writeArrayMapInternal(Parcel.java:723)
at android.os.BaseBundle.writeToParcelInner(BaseBundle.java:1408)
at android.os.Bundle.writeToParcel(Bundle.java:1133)
at android.os.Parcel.writeBundle(Parcel.java:763)
at android.app.ActivityManagerProxy.activityStopped(ActivityManagerNative.java:3697)
at android.app.ActivityThread$StopInfo.run(ActivityThread.java:3768)
at android.os.Handler.handleCallback(Handler.java:751)
at android.os.Handler.dispatchMessage(Handler.java:95)
at android.os.Looper.loop(Looper.java:154)
at android.app.ActivityThread.main(ActivityThread.java:6123)
at java.lang.reflect.Method.invoke(Native Method)
at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:867)
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:757)
Note: The weird thing is that one of fragment has the exact same code and is hosted inside the same activity, but when that fragment is active and app goes to background, interestingly the app is not crashing.
**Exam Model Class:
package in.crazybytes.bankmaniaadmin.models;
import java.io.Serializable;
public class Exam implements Serializable {
private String mExam_name;
private String mExam_key;
private Long mTime_added;
private int mNum_subjects;
private int mNum_questions;
public Exam(String exam_name, String exam_key, Long time_added, int num_subjects, int num_questions) {
mExam_name = exam_name;
mExam_key = exam_key;
mTime_added = time_added;
mNum_subjects = num_subjects;
mNum_questions = num_questions;
}
public Exam() {
}
public String getExam_name() {
return mExam_name;
}
public void setExam_name(String exam_name) {
mExam_name = exam_name;
}
public String getExam_key() {
return mExam_key;
}
public void setExam_key(String exam_key) {
mExam_key = exam_key;
}
public Long getTime_added() {
return mTime_added;
}
public void setTime_added(Long time_added) {
mTime_added = time_added;
}
public int getNum_subjects() {
return mNum_subjects;
}
public void setNum_subjects(int num_subjects) {
mNum_subjects = num_subjects;
}
public int getNum_questions() {
return mNum_questions;
}
public void setNum_questions(int num_questions) {
mNum_questions = num_questions;
}
}
Paper Model Class
package in.crazybytes.bankmaniaadmin.models;
import java.io.Serializable;
public class Paper implements Serializable {
private String mPaper_name;
private String mPaper_key;
private Long mTime_added;
private int mNum_questions;
public Paper(String paper_name, String paper_key, Long time_added, int num_questions) {
mPaper_name = paper_name;
mPaper_key = paper_key;
mTime_added = time_added;
mNum_questions = num_questions;
}
public Paper() {
}
public String getPaper_key() {
return mPaper_key;
}
public void setPaper_key(String paper_key) {
mPaper_key = paper_key;
}
public Long getTime_added() {
return mTime_added;
}
public void setTime_added(Long time_added) {
mTime_added = time_added;
}
public int getNum_questions() {
return mNum_questions;
}
public void setNum_questions(int num_questions) {
mNum_questions = num_questions;
}
public String getPaper_name() {
return mPaper_name;
}
public void setPaper_name(String paper_name) {
mPaper_name = paper_name;
}
}
Subject Model Class:
package in.crazybytes.bankmaniaadmin.models;
import java.io.Serializable;
public class Subject implements Serializable {
private String mSubject_name;
private String mSubject_key;
private Long mTime_added;
private int mNum_papers;
private int mNum_questions;
public Subject(String subject_name, String subject_key, Long time_added, int num_papers, int num_questions) {
mSubject_name = subject_name;
mSubject_key = subject_key;
mTime_added = time_added;
mNum_papers = num_papers;
mNum_questions = num_questions;
}
public Subject() {
}
public String getSubject_name() {
return mSubject_name;
}
public void setSubject_name(String subject_name) {
mSubject_name = subject_name;
}
public String getSubject_key() {
return mSubject_key;
}
public void setSubject_key(String subject_key) {
mSubject_key = subject_key;
}
public Long getTime_added() {
return mTime_added;
}
public void setTime_added(Long time_added) {
mTime_added = time_added;
}
public int getNum_papers() {
return mNum_papers;
}
public void setNum_papers(int num_papers) {
mNum_papers = num_papers;
}
public int getNum_questions() {
return mNum_questions;
}
public void setNum_questions(int num_questions) {
mNum_questions = num_questions;
}
}
Somehow QuestionsActivity is getting into the fragment save state, even if you don't intend for that to happen. While QuestionsActivity is being serialized, another object that is not serializable is being encountered. That's why you see TextViews and other things attempting to get serialized because all the instance variables of QuestionsActivity get serialized by default.
My best guess for why this is happening is due to this line:
args.putSerializable(Keys.FRAGMENT_ACTIVE_LISTENER, mOnFragmentActiveListener);
But it's difficult to know for sure without seeing where OnFragmentActiveListener is defined. I'm assuming either QuestionsActivity implements OnFragmentActiveListener, or QuestionsActivity defines OnFragmentActiveListener as an inner class. Either way, if you put an OnFragmentActiveListener into fragment arguments, you will encounter an exception because you indirectly are storing the entire QuestionsActivity as a fragment arg too. When a fragment stops, all fragment args become part of the fragment save state. And that's the cause of the error.
I would suggest not passing the OnFragmentActiveListener around as a fragment arg. If the OnFragmentActiveListener comes from the activity, just use getActivity() to get a reference to the activity and then get a reference to the listener.
I also noticed PaperListFragment implements Serializable and I'm assuming you did the same thing for QuestionsActivity. You probably did this to get around compile errors. But this has led to runtime errors because the instance variables on both of these classes are not all serializable. So to avoid more runtime issues, I would suggest never having activities or fragments implement serializable because these classes are inherently not serializable due to their members.
I'm developing an Android app using Google Sheets as a database.
I have information about books in a Google Sheet (title, author, cover, date, etc). I want to retrieve this information and show it in a "Listview" in the "Spreadsheets" Activity. I created a "BookItem" object and an "BookAdapter" adapter. In the "Spreadsheets.java" I have the read method, called "getDataFromApi()". I know that this method works, but I don't know how to adapt it to my "BookAdapter" and show the information on the ListView.
This is mi code:
public class BookItem {
static String title_item;
static Drawable cover_item; //probar con String
public BookItem(String title, Drawable cover){
super();
this.title_item = title;
this.cover_item = cover;
}
public String getTitle() {
return title_item;
}
public void setTitle(String title){
this.title_item = title;
}
public static Drawable getCover() {
return cover_item;
}
public void setCover(Drawable cover) {
this.cover_item = cover;}
This is my BookAdapter:
public class BookAdapter extends BaseAdapter {
private ArrayList<BookItem> items;
List<BookItem> items;
private Context context;
public BookAdapter (Context context, List<BookItem> items) {
this.context = context;
this.items = items;
}
#Override
public int getCount() {
return items.size();
}
#Override
public BookItem getItem(int position) {
return this.items.get(position);
}
#Override
public long getItemId(int i) {
return 0;
}
private static class ViewHolder {
public final ImageView cover_item;
public final TextView title_item;
public ViewHolder (ImageView cover_item, TextView title_item){
this.cover_item = cover_item;
this.title_item = title_item;
}
}
#Override
public View getView (int position, View view, ViewGroup viewGroup) {
ImageView cover_item;
TextView title_item;
if (view == null) {
view = LayoutInflater.from(context).inflate(R.layout.fila_lista_miestanteria, viewGroup, false); //se mete aqui en getView por ser baseAdapter
title_item = (TextView) view.findViewById(R.id.book_title_item);
cover_item = (ImageView) view.findViewById(R.id.book_cover_item);
view.setTag(R.id.book_title_item, title_item);
view.setTag(R.id.book_cover_item, cover_item);
}
else {
cover_item = (ImageView) view.getTag(R.id.book_cover_item);
title_item = (TextView)view.getTag(R.id.book_title_item);
}
BookItem bookItem = getItem(position);
cover_item.setImageDrawable(bookItem.getCover());
title_item.setText(bookItem.getTitle());
return view;
}
}
public class Spreadsheets extends Activity {
static String book_title, book_author, book_date, book_category, book_description, book_rating, book_cover;
static String read_only = "no";
static String book_favorite = "no";
static GoogleAccountCredential mCredential;
private ListView bookList;
private TextView mOutputText;
ProgressDialog mProgress;
Context context;
List<String> rst;
List<BookItem> resultados;
BookAdapter adapter;
private static final String[] SCOPES = {SheetsScopes.SPREADSHEETS};
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.spread);
// mOutputText = (TextView) findViewById(R.id.outputText);
bookList = (ListView) findViewById(R.id.bookList);
// mOutputText.setText("");
mProgress = new ProgressDialog(this);
mProgress.setMessage("Calling Google Sheets...");
// Initialize credentials and service object.
mCredential = GoogleAccountCredential.usingOAuth2(
getApplicationContext(), Arrays.asList(SCOPES))
.setBackOff(new ExponentialBackOff());
System.out.print("read only es igual a "+ read_only);
new MakeRequestTask(mCredential).execute();
}
public void rellenar(){
System.out.println("VOY A HACER NEW BOOK ADAPTER ");
adapter = new BookAdapter(context, resultados);
bookList.setAdapter(adapter);
System.out.println("SETADAPTER");
}
private class MakeRequestTask extends AsyncTask<Void, Void, List<String>> {
private Exception mLastError = null;
MakeRequestTask(GoogleAccountCredential credential) {
}
#Override
protected List<String> doInBackground(Void... params) {
try {
if(read_only.equals("no")) {
setDataToApi();
return null;
}
else {
return getDataFromApi();
}
} catch (Exception e) {
mLastError = e;
cancel(true);
return null;
}
}
private List<String> getDataFromApi() throws IOException {
String range = "Sheet1!A1:H";
List<String> results = new ArrayList<String>();
ValueRange response = CreateSpreadsheets.mService.spreadsheets().values()
.get(CreateSpreadsheets.spreadsheet_id, range)
.execute();
List<List<Object>> values = response.getValues();
if (values != null) {
for (List row : values) {
results.add(row.get(0) + ", " + row.get(7));
}
}
//funcion();
return results;
}
private void setDataToApi() throws IOException {
String range = "Sheet1!A2:H";
List<List<Object>> values = new ArrayList<>();
List<Object> data1 = new ArrayList<>();
data1.add(book_title);
data1.add(book_author);
data1.add(book_date);
data1.add(book_category);
data1.add(book_description);
data1.add(book_rating);
data1.add(book_cover);
data1.add("a");
values.add(data1);
ValueRange valueRange = new ValueRange();
valueRange.setMajorDimension("ROWS");
valueRange.setRange(range);
valueRange.setValues(values);
ValueRange body = new ValueRange().setValues(values);
AppendValuesResponse response =
CreateSpreadsheets.mService.spreadsheets().values().append(CreateSpreadsheets.spreadsheet_id, range, body)
.setValueInputOption("RAW")
.execute();
}
#Override
protected void onPreExecute() {
//mOutputText.setText("");
mProgress.show();
}
#Override
protected void onPostExecute(List<String> output) {
mProgress.hide();
if (output == null || output.size() == 0) {
// mOutputText.setText("No results returned.");
} else {
if(read_only.equals("no")) {
Intent intent = new Intent(Spreadsheets.this, MainActivity.class);
startActivity(intent);
// mOutputText.setText("Se ha añadido un libro a su lista");
}
else {
System.out.println("VOY A RELLENAR LA LISTA");
rellenar();
}
}
}
#Override
protected void onCancelled() {
}
}
}
The "spread.xml" is a list, and the "fila_list_miestanteria.xml" is a TextView&ImageView to show the book info.
Thank you so much!
Im trying to initialize my adapter from a callback method that is in another class, however, its not working, there are no logs or crashes. If I check the size of the adapter within that method, it shows the actual size but else where,it seems to be empty.
Here is my setup
The Adapter
public class SlidesAdapter extends FragmentPagerAdapter {
ArrayList<String> pictureUrls = new ArrayList<>();
private String type;
private Context ctx;
public SlidesAdapter(FragmentManager fm, ArrayList<String> pictureUrls, String type, Context ctx) {
super(fm);
this.pictureUrls = pictureUrls;
this.type = type;
this.ctx = ctx;
}
#Override
public Fragment getItem(int position) {
return SlidesFragment.newInstance(pictureUrls.get(position), type);
}
#Override
public int getCount() {
return pictureUrls.size();
}
#Override
public CharSequence getPageTitle(int position) {
return RedditClient.getInstance().getPageTitle(position);
}
}
My callback method
If I check the size of the adapter from this method, I get the actual size, but if I check from another place, e.g from within the adapter itself, its empty.
#Override
public void updateCollectionData( ArrayList<CollectionModel> collectionModelArrayList) {
this.collapsingToolbarLayout.setTitle(collectionModelArrayList.get(0).getCollectionName());
ArrayList<String> unsplashLinks = new ArrayList<>();
for (CollectionModel model : collectionModelArrayList){
unsplashLinks.add(String.valueOf(model.getCollectionID()));
}
Toaster.makeText(getApplicationContext(), String.valueOf(unsplashLinks.size()), Toaster.LENGTH_SHORT, Toaster.INFO).show();
mSectionsPagerAdapter = new SlidesAdapter(getSupportFragmentManager(), unsplashLinks, Contract.UNSPLASH_TYPE, getApplicationContext());
mProgressBar.hide();
}
This method here provides data to my callback method:
public void getCollections(MainActivity mainActivity){
this.callBacks = mainActivity;
Retrofit retrofit = RetrofitClient.getInstance().initialize(Contract.UNSPLASH_BASE_URL);
UnsplashApi service = retrofit.create(UnsplashApi.class);
Call<List<UnsplashPojo>> call = service.getFeaturedCollectionList(Contract.UNSPLASH_APP_ID);
call.enqueue(new Callback<List<UnsplashPojo>>() {
#Override
public void onResponse(Call<List<UnsplashPojo>> call, Response<List<UnsplashPojo>> response) {
CollectionModel collectionModel;
for (UnsplashPojo unsplashPojo : response.body()){
collectionModel = new CollectionModel(unsplashPojo.title, unsplashPojo.id);
collectionModelArrayList.add(collectionModel);
}
callBacks.updateCollectionData(collectionModelArrayList);
}
#Override
public void onFailure(Call<List<UnsplashPojo>> call, Throwable t) {
t.printStackTrace();
}
});
}
I think your problem is here.
#Override
public CharSequence getPageTitle(int position) {
return RedditClient.getInstance().getPageTitle(position);
}
this line RedditClient.getInstance().getPageTitle(position); is excuting in another thread other than the thread in which your adapter is initialized.
Suggestion for testing :
add fake titles list. If it works. then initialize your adapter and the title list just after you get all data needed by the adapter.