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notifyDataSetChanged() blanks out recyclerview

I have an issue where notifyDataSetChanged() in a response call will blank out the recyclerview but if the Adapter is initiated manually with a onClick, the recyclerview works. I have tested that the List has the items inside before calling notifyDataSetChanged() so i'm not sure what's wrong here.
[Main Activity] This works but i have to manually click the bnQuery.
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
apiInterface = API_client.getClient().create(APIInterface.class);
etCoin = (EditText) findViewById(R.id.etCoin);
bnQuery = (Button) findViewById(R.id.bnQuery);
rcvMain = findViewById(R.id.rcvMain);
getCoinData("2");
//initRCV_Main();
bnQuery.setOnClickListener(new View.OnClickListener() {
#Override
public void onClick(View v) {
//getCoinData("2");
initRCV_Main();
}
});
}
private void initRCV_Main() {
rcvMainAdp = new rcvMainAdapter(cList);
rcvMain.setAdapter(rcvMainAdp);
rcvMain.setLayoutManager(new LinearLayoutManager(this));
}
private void getCoinData(String coinLimit){
Call<cInfoPack> call = apiInterface.doGetCoinData(coinLimit);
call.enqueue(new Callback<cInfoPack>() {
#Override
public void onResponse(Call<cInfoPack> call, Response<cInfoPack> response) {
cInfoPack list = response.body();
List<cData> listSorter = new ArrayList<>();
listSorter.addAll(list.getData());
Collections.sort(listSorter, new SortbyVolChg());
cList.clear();
cList = listSorter;
System.out.println("list " + list.getData().get(0).getQuote());
System.out.println("listSorter " + listSorter.get(0).getQuote());
System.out.println("cList " + cList.get(0).getQuote());
//rcvMainAdp.notifyDataSetChanged();
}
#Override
public void onFailure(Call<cInfoPack> call, Throwable t) {
Toast.makeText(MainActivity.this, "onFailure", Toast.LENGTH_SHORT).show();
Log.d("XXXX", t.getLocalizedMessage());
call.cancel();
}
});
}
[Main Activity] If i initiate the recyclerview during onCreate and use the notifyDataSetChanged() during getCoinData, I get a blank recycleview. system.out shows that the lists all contain information in them.
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
apiInterface = API_client.getClient().create(APIInterface.class);
etCoin = (EditText) findViewById(R.id.etCoin);
bnQuery = (Button) findViewById(R.id.bnQuery);
rcvMain = findViewById(R.id.rcvMain);
getCoinData("2");
initRCV_Main();
bnQuery.setOnClickListener(new View.OnClickListener() {
#Override
public void onClick(View v) {
//getCoinData("2");
//initRCV_Main();
}
});
}
private void initRCV_Main() {
rcvMainAdp = new rcvMainAdapter(cList);
rcvMain.setAdapter(rcvMainAdp);
rcvMain.setLayoutManager(new LinearLayoutManager(this));
}
private void getCoinData(String coinLimit){
Call<cInfoPack> call = apiInterface.doGetCoinData(coinLimit);
call.enqueue(new Callback<cInfoPack>() {
#Override
public void onResponse(Call<cInfoPack> call, Response<cInfoPack> response) {
cInfoPack list = response.body();
List<cData> listSorter = new ArrayList<>();
listSorter.addAll(list.getData());
Collections.sort(listSorter, new SortbyVolChg());
cList.clear();
cList = listSorter;
System.out.println("list " + list.getData().get(0).getQuote());
System.out.println("listSorter " + listSorter.get(0).getQuote());
System.out.println("cList " + cList.get(0).getQuote());
rcvMainAdp.notifyDataSetChanged();
}
#Override
public void onFailure(Call<cInfoPack> call, Throwable t) {
Toast.makeText(MainActivity.this, "onFailure", Toast.LENGTH_SHORT).show();
Log.d("XXXX", t.getLocalizedMessage());
call.cancel();
}
});
}
[Adapter]
public class rcvMainAdapter extends RecyclerView.Adapter<rcvMainAdapter.ViewHolder> {
private List<cData> idxCoin;
//ItemClickListener itemClickListener;
rcvMainAdapter(List<cData> data) {this.idxCoin = data;}
#NonNull
#NotNull
#Override
public ViewHolder onCreateViewHolder(#NonNull #NotNull ViewGroup parent, int viewType) {
Context context = parent.getContext();
LayoutInflater inflater = LayoutInflater.from(context);
View view = inflater.inflate(R.layout.rcv_main,parent, false);
ViewHolder viewHolder = new ViewHolder(view);
return viewHolder;
}
#Override
public void onBindViewHolder(#NonNull #NotNull ViewHolder holder, int position) {
cData cdata = idxCoin.get(position);
TextView tvSym = holder.tvSymbol;
tvSym.setText(cdata.getSymbol());
TextView tvQuo = holder.tvQuote;
BigDecimal tvQuote_BD = new BigDecimal(cdata.getQuote().getuSD().getPrice().toString());
tvQuote_BD.setScale(6, RoundingMode.DOWN);
tvQuo.setText(tvQuote_BD.toString());
TextView tvV24 = holder.tvVolume24;
BigDecimal tvVolume24_BD = new BigDecimal(cdata.getQuote().getuSD().getVolume24h().toString());
BigInteger tvVolume24_BI = tvVolume24_BD.toBigInteger();
tvV24.setText(tvVolume24_BI.toString());
}
#Override
public int getItemCount() {
return idxCoin.size();
}
public class ViewHolder extends RecyclerView.ViewHolder {
TextView tvSymbol, tvQuote, tvVolume24;
public ViewHolder(#NonNull #NotNull View itemView) {
super(itemView);
tvSymbol = itemView.findViewById(R.id.tvSymbol);
tvQuote = itemView.findViewById(R.id.tvQuote);
tvVolume24 = itemView.findViewById(R.id.tvVolume24);
//itemView.setOnClickListener(this);
}
}
/*
public interface ItemClickListener{
void onItemClick(View view, int position);
}
*/
}
PS: apologies for the rubbish coding as this is self taught and modifying some codes found online.

Remove this in response.
cList.clear();
Add This line in response
rcvMainAdp.setdata(listSorter);
In rcvMainAdp Adapter, Create a Method setdata()
public void setdata(ArrayList<cData> data) {
this.idxCoin = data;
notifyDataSetChanged();
}

Problem most likely is that when you call initRCV_Main() You set the adapter to the list as in rcvMainAdp = new rcvMainAdapter(cList); And when list is changed and you set it to adapter it functions.
But when you call getCoinData() and rcvMainAdp.notifyDataSetChanged(); at the end you never set the changed list to the adapter until you click initRCV_Main() again.
So maybe the fix is calling rcvMainAdp = new rcvMainAdapter(cList) and then
rcvMainAdp.notifyDataSetChanged();

Nested Recycler View, Child And Parent Remove Issue

I have created a Nested recycle rview with parent and child both dynamic.Addition to both Parent and Child is working fine.Deletion from child is working fine.I want to remove parent view when all the child views for the same is removed.Confused about how could i implement the same.
Here is the child Adapter
public class MyAdapter extends RecyclerView.Adapter<MyAdapter.ViewHolder> {
private List<ToDoModel> values;
private Context context;
//private OnEditListener onEditListener;
AlertDialog alertDialog;
/*public MyAdapter(List<ToDoModel> context) {
this.values = context;
this.onEditListener = onEditListener;
}*/
public static class ViewHolder extends RecyclerView.ViewHolder {
public TextView txtHeader;
public TextView txtFooter;
public ImageView mIcon;
public View layout;
public ImageView deleteItem;
public CheckBox doneButton;
public ImageView editItem;
public ViewHolder(View v) {
super(v);
layout = v;
txtHeader = (TextView) v.findViewById(R.id.firstLine);
txtFooter = (TextView) v.findViewById(R.id.secondLine);
mIcon = (ImageView) v.findViewById(R.id.icon);
deleteItem = (ImageView) v.findViewById(R.id.deleteButton);
doneButton = (CheckBox) v.findViewById(R.id.checkBox);
editItem = (ImageView) v.findViewById(R.id.editButton);
}
}
public void add(int position, ToDoModel item) {
values.add(position, item);
sort();
notifyDataSetChanged();
//notifyItemInserted(position);
}
public void replace(ToDoModel item)
{
int editPos;
editPos = values.indexOf(item);
values.set(editPos,item);
sort();
notifyDataSetChanged();
}
public void sort() {
if ((int) values.size() > 1) {
Collections.sort(values);
}
}
public void remove(int position) {
values.remove(position);
notifyDataSetChanged();
}
public MyAdapter(List<ToDoModel> myDataset) {
values = myDataset;
}
#Override
public MyAdapter.ViewHolder onCreateViewHolder(ViewGroup parent,
int viewType) {
LayoutInflater inflater = LayoutInflater.from(
parent.getContext());
View v =
inflater.inflate(R.layout.todo_row_view, parent, false);
ViewHolder vh = new ViewHolder(v);
return vh;
}
#Override
public void onBindViewHolder(ViewHolder holder, final int position) {
final ToDoModel toDoModel = values.get(position);
switch ((String) toDoModel.task) {
case "To Go":
holder.mIcon.setImageResource(R.drawable.ic_explore24px);
break;
case "To Get":
holder.mIcon.setImageResource(R.drawable.ic_shoppingbag24px);
break;
case "To Do":
holder.mIcon.setImageResource(R.drawable.ic_todo);
break;
default:
break;
}
holder.txtHeader.setText(toDoModel.header);
holder.txtFooter.setText(toDoModel.task + " | " + toDoModel.tod + " | " + toDoModel.footer);
holder.doneButton.setOnCheckedChangeListener(new CompoundButton.OnCheckedChangeListener() {
#Override
public void onCheckedChanged(CompoundButton buttonView, boolean isChecked) {
if (buttonView.isChecked()) {
//holder.mIcon.setImageResource(R.drawable.ic_check_circle24px);
Toast.makeText(buttonView.getContext(), "Marked As Done", Toast.LENGTH_SHORT).show();
} else {
Toast.makeText(buttonView.getContext(), "Marked As UnDone", Toast.LENGTH_SHORT).show();
}
}
});
holder.deleteItem.setOnClickListener(new OnClickListener() {
#Override
public void onClick(View v) {
AlertDialog.Builder builder = new AlertDialog.Builder(v.getContext());
View view = LayoutInflater.from(v.getContext()).inflate(R.layout.delete_promptdialog,null);
Button YesButton = (Button) view.findViewById(R.id.buttonYes);
Button NoButton = (Button) view.findViewById(R.id.buttonNo);
YesButton.setOnClickListener(new View.OnClickListener() {
#Override
public void onClick(View v) {
remove(position);
Toast.makeText(v.getContext(), "List Item Removed", Toast.LENGTH_SHORT).show();
alertDialog.dismiss();
}
});
NoButton.setOnClickListener(new View.OnClickListener() {
#Override
public void onClick(View v) {
Toast.makeText(v.getContext(), "Delete Canceled", Toast.LENGTH_SHORT).show();
alertDialog.dismiss();
}
});
builder.setView(view);
alertDialog=builder.create();
alertDialog.show();
/*remove(position);
Toast.makeText(v.getContext(), "List Item Removed", Toast.LENGTH_SHORT).show();*/
}
});
/* holder.editItem.setOnClickListener(new OnClickListener() {
#Override
public void onClick(View v) {
onEditListener.onEditClick(values.get(position));
//Toast.makeText(v.getContext(), "List Edit", Toast.LENGTH_SHORT).show();
}
});*/
}
/*public interface OnEditListener {
void onEditClick(ToDoModel currentData);
}*/
#Override
public int getItemCount() {
return values.size();
}
}
Here is the Parent Adapter
public class ParentAdapter extends RecyclerView.Adapter<ParentAdapter.ParentViewHolder> {
private RecyclerView.RecycledViewPool viewPool = new RecyclerView.RecycledViewPool();
public List<TodoParent> parentList;
public TodoParent todayList;
public static long todayEpochDate;
public ParentAdapter(List<TodoParent> parentList, MainFragment mainFragment) {
this.parentList = parentList;
}
public void add(int position, TodoParent item) {
parentList.add(position, item);
sort();
notifyDataSetChanged();
//notifyItemInserted(position);
}
public void sort() {
if ((int) parentList.size() > 1) {
Collections.sort(parentList);
//if(!(todayList.ParentTitle.isEmpty())) Collections.swap(parentList, parentList.indexOf(todayList), 0);
}
/* if ( todayList )
{
System.out.println("Entering Swap");
setToday(todayList);
}*/
}
public void setToday(TodoParent item) {
int todayPos;
todayPos = parentList.indexOf(item);
parentList.remove(todayPos);
notifyDataSetChanged();
parentList.add(0,item);
notifyDataSetChanged();
}
#NonNull
#Override
public ParentAdapter.ParentViewHolder onCreateViewHolder(#NonNull ViewGroup parent, int viewType) {
View view = LayoutInflater.from(parent.getContext()).inflate(R.layout.todo_parent_view,parent,false);
ParentViewHolder vh = new ParentViewHolder(view);
return vh;
}
#RequiresApi(api = Build.VERSION_CODES.N)
#Override
public void onBindViewHolder(#NonNull ParentViewHolder holder, int position) {
TodoParent todoParent = parentList.get(position);
todoParent.ParentId = position;
Calendar mCal;
mCal = Calendar.getInstance();
int mDay = mCal.get(Calendar.DAY_OF_MONTH);
int mMonth = mCal.get(Calendar.MONTH);
int mYear = mCal.get(Calendar.YEAR);
String dateString = mDay +"/"+ (mMonth+1) +"/" + mYear;
try {
todayEpochDate = new SimpleDateFormat("dd/MM/yyyy").parse(dateString).getTime()/1000;
} catch (ParseException e) {
e.printStackTrace();
}
if((long)todayEpochDate == (long)todoParent.EpochTime)
{
holder.mTitle.setText("Today");
todayList = todoParent;
System.out.println("todayE:"+todayEpochDate);
System.out.println("SelectedE:"+todoParent.EpochTime);
}
else
{
holder.mTitle.setText(todoParent.ParentTitle);
System.out.println("today:"+todayEpochDate);
System.out.println("Selected:"+todoParent.EpochTime);
}
LinearLayoutManager layoutManager = new LinearLayoutManager(holder.childView.getContext(),
LinearLayoutManager.VERTICAL,false);
layoutManager.setInitialPrefetchItemCount(todoParent.mChildList.size());
holder.childView.setLayoutManager(layoutManager);
MyAdapter myAdapter = new MyAdapter(todoParent.mChildList);
holder.childView.setAdapter(myAdapter);
holder.childView.setRecycledViewPool(viewPool);
}
#Override
public int getItemCount() {
return parentList.size();
}
public class ParentViewHolder extends RecyclerView.ViewHolder {
public TextView mTitle;
public RecyclerView childView;
public ParentViewHolder(#NonNull View itemView) {
super(itemView);
mTitle = itemView.findViewById(R.id.mParentTitle);
childView = itemView.findViewById(R.id.mChildView);
}
}
}
remove for child is working fine. How to remove Parent here when there are no more child views?

Calculate the number of items displayed by RecyclerView and place in a TextView

Currently I can display all of the items in my RecyclerView. What I wish to do is calculate how many of these items there are. My items are saved in CardView. I don't want to calculate or sum any particular field, just the number of actual items. Here is my code and I have tried to set it up using getItemCount() method and attach this to a TextView and display outside of RecyclerView. This is not working for me:
public class COM800s1 extends AppCompatActivity {
private FirebaseFirestore db = FirebaseFirestore.getInstance();
private CollectionReference attendanceRef = db.collection("Attendance");
private AttendanceAdapter adapter;
private Context context;
private TextView attendanceNumbers;
private int counter;
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_com800s1);
attendanceNumbers = findViewById(R.id.attendanceNums);
FloatingActionButton floatingActionButton = findViewById(R.id.button_add_session);
floatingActionButton.setOnClickListener(new View.OnClickListener() {
#Override
public void onClick(View v) {
startActivity(new Intent(COM800s1.this,NewAttendanceRecord.class));
}
});
setUpRecyclerView();
}
private void setUpRecyclerView() {
final Query query = attendanceRef.whereEqualTo("sessionID", "5I0PLcpgmwdcjKLYLgkU").orderBy("userEmail", Query.Direction.ASCENDING);
FirestoreRecyclerOptions<Attendance> options = new FirestoreRecyclerOptions.Builder<Attendance>()
.setQuery(query, Attendance.class).build();
adapter = new AttendanceAdapter(options);
RecyclerView recyclerView = findViewById(R.id.recycler_view);
recyclerView.setHasFixedSize(true);
recyclerView.setLayoutManager(new LinearLayoutManager(this));
recyclerView.setAdapter(adapter);
//counter = adapter.getItemCount();
//attendanceNumbers.setText("Currently " +counter+ " students have attended this session");
new ItemTouchHelper(new ItemTouchHelper.SimpleCallback(0,
ItemTouchHelper.LEFT | ItemTouchHelper.RIGHT) {
#Override
public boolean onMove(RecyclerView recyclerView, RecyclerView.ViewHolder viewHolder, RecyclerView.ViewHolder target) {
return false;
}
#Override
public void onSwiped(RecyclerView.ViewHolder viewHolder, int direction) {
adapter.deleteItem(viewHolder.getAdapterPosition());
}
}).attachToRecyclerView(recyclerView);
adapter.setSetOnItemClickListener(new AttendanceAdapter.OnItemClickListener() {
#Override
public void onItemClick(Attendance documentSnapshot, int position) {
}
});
}
#Override
protected void onStart () {
super.onStart();
adapter.startListening();
}
#Override
protected void onStop(){
super.onStop();
adapter.stopListening();
}
}
Here is my Adapter code:
public class AttendanceAdapter extends FirestoreRecyclerAdapter<Attendance, AttendanceAdapter.AttendanceHolder>{
private AttendanceAdapter.OnItemClickListener listener;
public AttendanceAdapter(#NonNull FirestoreRecyclerOptions<Attendance> options) {
super(options);
}
#Override
protected void onBindViewHolder(#NonNull AttendanceHolder holder, int position, #NonNull Attendance model) {
holder.textViewStudent.setText(model.getUserEmail());
holder.textViewTime.setText(model.getSignInTime());
holder.textViewSession.setText(model.getSessionID());
holder.textViewUserUID.setText(model.getUserUID());
}
#NonNull
#Override
public AttendanceHolder onCreateViewHolder(#NonNull ViewGroup parent, int viewType) {
View v = LayoutInflater.from(parent.getContext()).inflate(R.layout.attendance_item, parent, false);
return new AttendanceAdapter.AttendanceHolder(v);
}
public void deleteItem(int position){
getSnapshots().getSnapshot(position).getReference().delete();
}
public int countItems(){
return getItemCount();
}
class AttendanceHolder extends RecyclerView.ViewHolder {
TextView textViewStudent;
TextView textViewTime;
TextView textViewSession;
TextView textViewUserUID;
public AttendanceHolder(View itemView){
super(itemView);
textViewStudent = itemView.findViewById(R.id.text_view_student_name);
textViewTime = itemView.findViewById(R.id.text_view_course);
textViewSession = itemView.findViewById(R.id.text_view_student_ID);
textViewUserUID = itemView.findViewById(R.id.text_view_user_UID);
itemView.setOnClickListener(new View.OnClickListener() {
#Override
public void onClick(View v) {
int position = getAdapterPosition();
if (position != RecyclerView.NO_POSITION && listener != null){
listener.onItemClick(getSnapshots().get(position),position);
}
}
});
}
}
public interface OnItemClickListener{
void onItemClick(Attendance documentSnapshot, int position);
}
public void setSetOnItemClickListener(AttendanceAdapter.OnItemClickListener listener){
this.listener = listener;
}
Here is my updates code which returns null pointer object on the onClickListener:
public class COM800s1 extends AppCompatActivity {
private FirebaseFirestore db = FirebaseFirestore.getInstance();
private CollectionReference attendanceRef = db.collection("Attendance");
private AttendanceAdapter adapter;
private TextView attendanceNumbers;
private TextView attendanceNumbs;
private Button attendanceButton;
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_com800s1);
attendanceNumbs = findViewById(R.id.attendanceNums);
attendanceButton = findViewById(R.id.calculateAttendance);
FloatingActionButton floatingActionButton = findViewById(R.id.button_add_session);
floatingActionButton.setOnClickListener(new View.OnClickListener() {
#Override
public void onClick(View v) {
startActivity(new Intent(COM800s1.this,NewAttendanceRecord.class));
}
});
setUpRecyclerView();
attendanceButton.setOnClickListener(new View.OnClickListener() {
#Override
public void onClick(View v) {
attendanceRef.whereEqualTo("sessionID", "5I0PLcpgmwdcjKLYLgkU").get().addOnCompleteListener(new OnCompleteListener<QuerySnapshot>() {
#Override
public void onComplete(#NonNull Task<QuerySnapshot> task) {
if (task.isSuccessful()) {
int count = 0;
for (DocumentSnapshot document : task.getResult()) {
count++;
attendanceNumbs = findViewById(R.id.attendanceNums);
attendanceNumbs.setText(count);
}
Log.d("TAG", count + "");
} else {
}
}
});
}
});
}
private void setUpRecyclerView() {
final Query query = attendanceRef.whereEqualTo("sessionID", "5I0PLcpgmwdcjKLYLgkU").orderBy("userEmail", Query.Direction.ASCENDING);
FirestoreRecyclerOptions<Attendance> options = new FirestoreRecyclerOptions.Builder<Attendance>()
.setQuery(query, Attendance.class).build();
adapter = new AttendanceAdapter(options);
RecyclerView recyclerView = findViewById(R.id.recycler_view);
recyclerView.setHasFixedSize(true);
recyclerView.setLayoutManager(new LinearLayoutManager(this));
recyclerView.setAdapter(adapter);
new ItemTouchHelper(new ItemTouchHelper.SimpleCallback(0,
ItemTouchHelper.LEFT | ItemTouchHelper.RIGHT) {
#Override
public boolean onMove(RecyclerView recyclerView, RecyclerView.ViewHolder viewHolder, RecyclerView.ViewHolder target) {
return false;
}
#Override
public void onSwiped(RecyclerView.ViewHolder viewHolder, int direction) {
adapter.deleteItem(viewHolder.getAdapterPosition());
}
}).attachToRecyclerView(recyclerView);
adapter.setSetOnItemClickListener(new AttendanceAdapter.OnItemClickListener() {
#Override
public void onItemClick(Attendance documentSnapshot, int position) {
}
});
}
#Override
protected void onStart () {
super.onStart();
adapter.startListening();
}
#Override
protected void onStop(){
super.onStop();
adapter.stopListening();
}
}

If you want to get the list of your recyclerView just create a static method in your recyclerView's adapter and just return your list in that.
for example:
public static List<modelOfYourList> getCount(){
return yourAdapterList;
}

Perhaps add something like this to your AttendanceAdapter class?
I took a look at the FirestoreRecyclerOptionsclass, which exposes a getSnapshots() method. This returns a ObservableSnapshotArray, which in turn extends from Base ObservableSnapshotArray, which exposes a size() method.
class AttendanceAdapter extends FirestoreRecyclerAdapter<Attendance, AttendanceAdapter.AttendanceHolder>{
{
private FirestoreRecyclerOptions<Attendance> options;
public AttendanceAdapter(#NonNull FirestoreRecyclerOptions<Attendance> options)
{
super(options);
this.options = options;
}
#Override
public int getItemCount()
{
final int count = options.getSnapshots() != null
? options.getSnapshots().size()
: 0;
return count;
}
Sources:
FirestoreRecyclerOptions
ObservableSnapshotArray
BaseObservableSnapshotArray
Update: I see that the FirestoreRecyclerAdapter already has a getItemCount method already and you are calling it. Perhaps the data has not yet returned? What are you seeing for the count when you print it?

If you are trying to make the counter variable as a global variable and use it outside the callback it will always be null because as #Vinnie mentioned in his answer, the data has not finished loading yet. What's really happening is that you are trying to get the data from the database and immediately use it it while the counter variable has the initial value of 0. Then, when getting the data from the database completes, it changes counter's value, but it's never read again. To solve this, the use result of your getItemCount() method inside your adapter class to set it's value to the TextView.
If you want to count the number of documents beneath a collection, please also see my answer from this post.

How to scroll to load More Data On Recycler View?

i want know how to scroll to get more data on my recycler view
example my using wordpress api to have 10post from my website
and i want to get 5 per load in recycler and scroll more to get 5 post more
but i don't know how to coding please than a look and give me some correct idea !!
News_list.java
/**
* A simple {#link Fragment} subclass.
*/
public class News_List extends Fragment {
private static final String URL = "https://chsknews.com/wp-json/wp/v2/posts/";
private RecyclerView recyclerView;
private RecyclerView.Adapter adapter;
private List<News_Item> news_itemList;
private SwipeRefreshLayout swipeRefreshLayout;
public News_List() {
// Required empty public constructor
}
#Override
public View onCreateView(LayoutInflater inflater, ViewGroup container,
Bundle savedInstanceState) {
// Inflate the layout for this fragment
View rootView = inflater.inflate(R.layout.fragment_news__list, container, false);
swipeRefreshLayout = (SwipeRefreshLayout) rootView.findViewById(R.id.swipe_refresh);
recyclerView = (RecyclerView) rootView.findViewById(R.id.MRecyclerView);
recyclerView.setHasFixedSize(true);
recyclerView.setLayoutManager(new LinearLayoutManager(getContext()));
news_itemList = new ArrayList<>();
News_Loader();
swipeRefreshLayout.setOnRefreshListener(new SwipeRefreshLayout.OnRefreshListener() {
#Override
public void onRefresh() {
News_Loader();
Toast.makeText(getContext(),"ដំណើរការជោគជ័យក្នុងការទាញយកពត៏មានចុងក្រោយ",Toast.LENGTH_SHORT).show();
news_itemList.clear();
}
});
return rootView;
}
private void News_Loader() {
final ProgressDialog progressDialog = new ProgressDialog(getContext());
progressDialog.setMessage("Loading News");
progressDialog.show();
StringRequest stringRequest = new StringRequest(Request.Method.GET,
URL,
new Response.Listener<String>() {
#Override
public void onResponse(String response) {
progressDialog.dismiss();
try {
//JSONObject jsonObject = new JSONObject(response);
JSONArray array = new JSONArray(response);
for (int i = 0; i < array.length(); i++){
JSONObject o = array.getJSONObject(i);
// Log.v("ID",o.getJSONObject("content").optString("rendered"));
news_itemList.add(new News_Item(
o.getJSONObject("title").getString("rendered"),
o.getString("date"),
o.getJSONObject("better_featured_image").getString("source_url"),
o.getString("date"),
o.getJSONObject("content").getString("rendered"))
);
// news_itemList.add(news_item);
}
adapter = new CustomAdapter(news_itemList,getContext());
recyclerView.setAdapter(adapter);
if (swipeRefreshLayout.isRefreshing())
{
swipeRefreshLayout.setRefreshing(false);
}
} catch (JSONException e) {
e.printStackTrace();
}
}
}, new Response.ErrorListener() {
#Override
public void onErrorResponse(VolleyError error) {
progressDialog.dismiss();
Toast.makeText(getContext(), error.getMessage(),Toast.LENGTH_LONG).show();
if (swipeRefreshLayout.isRefreshing())
{
swipeRefreshLayout.setRefreshing(false);
}
}
});
RequestQueue requestQueue = Volley.newRequestQueue(getContext());
requestQueue.add(stringRequest);
}
}
Adapter Class
public class CustomAdapter extends RecyclerView.Adapter<CustomAdapter.ViewHolder> {
private List<News_Item> news_items;
private Context context;
public CustomAdapter(List<News_Item> news_items, Context context) {
this.news_items = news_items;
this.context = context;
}
#Override
public ViewHolder onCreateViewHolder(ViewGroup parent, int viewType) {
View v = LayoutInflater.from(parent.getContext())
.inflate(R.layout.card_view,parent,false);
return new ViewHolder(v);
}
#Override
public void onBindViewHolder(ViewHolder holder, final int position) {
final News_Item news_item = news_items.get(position);
holder.title.setText(Html.fromHtml(news_item.getTitle()));
holder.news_date.setText((news_item.getNews_date()));
Picasso.with(context)
.load(news_item.getImage_url())
.fit()
.into(holder.news_img);
holder.news_img.setOnClickListener(new View.OnClickListener() {
#Override
public void onClick(View v) {
Intent intent = new Intent(context,News_Single_Post.class);
intent.setFlags(Intent.FLAG_ACTIVITY_NEW_TASK | Intent.FLAG_ACTIVITY_SINGLE_TOP);
intent.putExtra("source_url",news_items.get(position).getImage_url());
intent.putExtra("rendered", news_items.get(position).getTitle());
intent.putExtra("date",news_items.get(position).getNews_date());
intent.putExtra("content",news_items.get(position).getNews_content());
context.startActivity(intent);
}
});
}
#Override
public int getItemCount() {
return news_items.size();
}
public class ViewHolder extends RecyclerView.ViewHolder{
public TextView title;
public TextView news_date;
public ImageView news_img;
public ViewHolder(View itemView) {
super(itemView);
title = (TextView) itemView.findViewById(R.id.news_title);
news_date = (TextView) itemView.findViewById(R.id.news_date);
news_img = (ImageView) itemView.findViewById(R.id.news_image);
}
}
}

private boolean loading = true;
int pastVisiblesItems, visibleItemCount, totalItemCount;
mRecyclerView.addOnScrollListener(new RecyclerView.OnScrollListener()
{
#Override
public void onScrolled(RecyclerView recyclerView, int dx, int dy)
{
if(dy > 0) //check for scroll down
{
visibleItemCount = mLayoutManager.getChildCount();
totalItemCount = mLayoutManager.getItemCount();
pastVisiblesItems = mLayoutManager.findFirstVisibleItemPosition();
if (loading)
{
if ( (visibleItemCount + pastVisiblesItems) >= totalItemCount)
{
loading = false;
Log.v("...", "Last Item Wow !");
//Do pagination.. i.e. fetch new data
}
}
}
}
});
Don't forget to add
LinearLayoutManager mLayoutManager;
mLayoutManager = new LinearLayoutManager(this);
mRecyclerView.setLayoutManager(mLayoutManager);

Check if all items in RecyclerView have the same value (google Firestore)

I need to chceck if all items on adapter have a boolean value = true
Then based on result i have to change floatingActionButton color.
I have no idea how to do it.
Here is my Adapter:
private FirebaseFirestore db = FirebaseFirestore.getInstance();
private CollectionReference basementReference = db.collection("basement");
private TableAdapter tableAdapter;
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
FloatingActionButton basement = findViewById(R.id.button_basement);
basement.setOnClickListener(new View.OnClickListener() {
#Override
public void onClick(View view) {
Intent intent = new Intent(MainActivity.this, MainActivity.class);
startActivity(intent);
}
});
setUpRecyclerView();
}
private void setUpRecyclerView(){
final Query query = basementReference.orderBy("tableNumber",Query.Direction.ASCENDING);
FirestoreRecyclerOptions<Table> options = new FirestoreRecyclerOptions.Builder<Table>()
.setQuery(query, Table.class)
.build();
tableAdapter = new TableAdapter(options);
RecyclerView recyclerView = findViewById(R.id.recycler_view);
recyclerView.setHasFixedSize(true);
recyclerView.setLayoutManager(new LinearLayoutManager(this));
recyclerView.setAdapter(tableAdapter); tableAdapter.setOnItemClickListener(new TableAdapter.OnItemCLickListener() {
#Override
public void onItemClick(final DocumentSnapshot documentSnapshot, int position) {
Table table = documentSnapshot.toObject(Table.class);
if(table.isTableOccupied()){
basementReference.document(documentSnapshot.getId()).update("tableOccupied",false).addOnCompleteListener(new OnCompleteListener<Void>() {
}else {
basementReference.document(documentSnapshot.getId()).update("tableOccupied",true).addOnCompleteListener(new OnCompleteListener<Void>() {
}
#Override
protected void onStart() {
super.onStart();
tableAdapter.startListening();
}
please help. i tthink i need to do it in my adapter class, but if there is other solution i'll be glad to follow :)
tableAdapter class:
class TableAdapter extends FirestoreRecyclerAdapter {
public TableAdapter(#NonNull FirestoreRecyclerOptions<Table> options) {
super(options);
}
private OnItemCLickListener onItemCLickListener;
private int occupiedMarker = 0;
#Override
protected void onBindViewHolder(#NonNull TableHolder holder, int position, #NonNull Table model) {
holder.textViewTableNumber.setText(model.getTableNumber());
holder.textViewTableSeats.setText(model.getTableSeats());
holder.textViewTableOccupied.setText(String.valueOf(model.isTableOccupied()));
}
#NonNull
#Override
public TableHolder onCreateViewHolder(#NonNull ViewGroup parent, int viewType) {
View v = LayoutInflater.from(parent.getContext()).inflate(R.layout.note_table,parent,false);
return new TableHolder(v);
}
class TableHolder extends RecyclerView.ViewHolder{
TextView textViewTableNumber;
TextView textViewTableSeats;
TextView textViewTableOccupied;
public TableHolder(#NonNull View itemView) {
super(itemView);
textViewTableNumber = itemView.findViewById(R.id.text_view_table_number);
textViewTableSeats = itemView.findViewById(R.id.text_view_table_seats);
textViewTableOccupied = itemView.findViewById(R.id.text_view_table_occupied);
itemView.setOnClickListener(new View.OnClickListener() {
#Override
public void onClick(View view) {
int position = getAdapterPosition();
if (position != RecyclerView.NO_POSITION && onItemCLickListener!=null){
onItemCLickListener.onItemClick( getSnapshots().getSnapshot(position), position );
}
}
});
}
}
public interface OnItemCLickListener {
void onItemClick(DocumentSnapshot documentSnapshot, int position);
}
public void setOnItemClickListener(OnItemCLickListener onItemClickListener){
this.onItemCLickListener = onItemClickListener;
}
}