ParseQuery NullPointer Exception Paradox

ParseQuery NullPointer Exception Paradox - java

This is a follow-up to my previous question: Parse RecyclerView Image Query
I am now having a paradoxical nullpointer exception. I am attempting to extract a list from an inner method, in the way outlined below.
public List<ParseObject> objectList;
public List<String> getData(String filter){
ParseQuery<ParseObject> query = ParseQuery.getQuery("Images");
query.whereEqualTo("category", filter);
query.findInBackground(new FindCallback<ParseObject>() {
public void done(List<ParseObject> downloads, com.parse.ParseException e) {
if (e == null) {
objectList=downloads;
} else {
Log.d("score", "Error: " + e.getMessage());
}
}
});
int size = objectList.size();
for (int i = 0; i<size; i++){
ParseFile file = (ParseFile) objectList.get(i).get("Image");
urlList.add(file.getUrl());
}
return urlList;
}
How do I solve this? What ways exist which are better than what I am using?
EDIT:
Here is what it's doing. At present there are no exceptions, but the recyclerview is not displaying anything.
#Override
public View onCreateView(LayoutInflater inflater, ViewGroup container,
Bundle savedInstanceState) {
View rootView = inflater.inflate(R.layout.activity_events, container, false);
setList("sport", rootView);
return rootView;
}
public void set() {
}
public void setList(String filter, View view){
RecyclerView recyclerView = (RecyclerView) view.findViewById(R.id.rv);
LinearLayoutManager linearLayoutManager = new LinearLayoutManager(getActivity());
recyclerView.setLayoutManager(linearLayoutManager);
MyAdapter myAdapter = new MyAdapter(getData(filter));
recyclerView.setAdapter(myAdapter);
}
EDIT 2: More updated code:
#Override
public View onCreateView(LayoutInflater inflater, ViewGroup container,
Bundle savedInstanceState) {
View rootView = inflater.inflate(R.layout.activity_events, container, false);
setList("sport", rootView);
return rootView;
}
public void set() {
}
public void setList(String filter, View view){
RecyclerView recyclerView = (RecyclerView) view.findViewById(R.id.rv);
LinearLayoutManager linearLayoutManager = new LinearLayoutManager(getActivity());
recyclerView.setLayoutManager(linearLayoutManager);
MyAdapter myAdapter = new MyAdapter(getData(filter));
recyclerView.setAdapter(myAdapter);
}
private List<String> urlList = new ArrayList<>();
public List<ParseObject> objectList = new ArrayList<>();
public int size;
public List<String> getData(String filter){
ParseQuery<ParseObject> query = ParseQuery.getQuery("Images");
query.whereEqualTo("category", filter);
query.findInBackground(new FindCallback<ParseObject>() {
public void done(List<ParseObject> downloads, com.parse.ParseException e) {
if (e == null) {
Toast.makeText(getActivity(), "Downloads retrieved", Toast.LENGTH_SHORT).show();
objectList.addAll(downloads);
} else {
Log.d("score", "Error: " + e.getMessage());
}
size = objectList.size();
}
});
for (int i = 0; i<size; i++){
ParseFile file = (ParseFile) objectList.get(i).get("Image");
urlList.add(file.getUrl());
}
return urlList;
}
EDIT 3: Updated, and I have added my adapter code.
View rootView;
#Override
public View onCreateView(LayoutInflater inflater, ViewGroup container,
Bundle savedInstanceState) {
rootView = inflater.inflate(R.layout.activity_events, container, false);
new GetUrlListTask(this).execute("sport");
return rootView;
}
public void set() {
}
private List<String> urlList = new ArrayList<>();
public List<ParseObject> objectList = new ArrayList<>();
public int size;
public List<String> getData(String filter){
ParseQuery<ParseObject> query = ParseQuery.getQuery("Images");
query.whereEqualTo("category", filter);
query.findInBackground(new FindCallback<ParseObject>() {
public void done(List<ParseObject> downloads, com.parse.ParseException e) {
if (e == null) {
Toast.makeText(getActivity(), "Downloads retrieved", Toast.LENGTH_SHORT).show();
objectList.addAll(downloads);
} else {
}
size = objectList.size();
}
});
for (int i = 0; i<size; i++){
ParseFile file = (ParseFile) objectList.get(i).get("Image");
urlList.add(file.getUrl());
}
return urlList;
}
private class GetUrlListTask extends AsyncTask<String,Void,List<String>>
{
private WeakReference<Fragment> weakRef;
public GetUrlListTask(Fragment frag){
weakRef = new WeakReference< Fragment >(frag);
}
#Override
protected List<String> doInBackground(String... filters) {
return getData(filters[0]);
}
#Override
protected void onPostExecute(List<String> urlList) {
Fragment frag = weakRef.get();
if (frag != null){
RecyclerView recyclerView = (RecyclerView) rootView.findViewById(R.id.rv);
LinearLayoutManager linearLayoutManager = new LinearLayoutManager(getActivity());
recyclerView.setLayoutManager(linearLayoutManager);
MyAdapter myAdapter = new MyAdapter(urlList);
recyclerView.setAdapter(myAdapter);
}
}
}
And My adapter:
List<String> urls;
ViewGroup parent;
public MyAdapter(List<String> urls){
this.urls=urls;
}
#Override
public MyViewHolder onCreateViewHolder(ViewGroup parent, int viewType) {
View view = LayoutInflater.from(parent.getContext()).inflate(R.layout.image_entry, parent);
MyViewHolder myViewHolder = new MyViewHolder(view);
this.parent=parent;
return myViewHolder;
}
#Override
public void onBindViewHolder(MyViewHolder holder, int position) {
Picasso.with(parent.getContext())
.load(urls.get(position))
.into(holder.photo);
Toast.makeText(parent.getContext(), urls.get(position), Toast.LENGTH_LONG).show();
}
#Override
public int getItemCount() {
return urls.size();
}
public static class MyViewHolder extends RecyclerView.ViewHolder{
ImageView photo;
public MyViewHolder(View itemView) {
super(itemView);
photo = (ImageView) itemView.findViewById(R.id.listImage);
}
}

So I am assuming that what you want to do is once you get the urlList, you want to update some view. If that's the case then I think what you want to do it run that whole method in a background task rather than just the query like so:
First change your getData() method:
public List<String> getData(String filter){
ParseQuery<ParseObject> query = ParseQuery.getQuery("Images");
query.whereEqualTo("category", filter);
objectList = query.find(); //I think you have to surround this by a try catch or have the method throw an exception
int size = objectList.size();
for (int i = 0; i<size; i++){
ParseFile file = (ParseFile) objectList.get(i).get("Image");
urlList.add(file.getUrl());
}
return urlList;
}
Note that since you are doing a network call, the above method now HAS to run from a background thread.
Then you can use something like an AsyncTask to update a view:
private class GetUrlListTask extends AsyncTask<String,Void,List<String>>
{
private WeakReference<Fragment> weakRef;
public PhotoTagsFetchTask(Fragment frag){
weakRef = new WeakReference< Fragment >(frag);
}
#Override
protected Void doInBackground(String... filters) {
return getData(filters[0]);
}
#Override
protected void onPostExecute(List<String> urlList) {
Fragment frag = weakRef.get();
if (frag != null){
RecyclerView recyclerView = (RecyclerView) view.findViewById(R.id.rv);
LinearLayoutManager linearLayoutManager = new LinearLayoutManager(getActivity());
recyclerView.setLayoutManager(linearLayoutManager);
MyAdapter myAdapter = new MyAdapter(urlList);
recyclerView.setAdapter(myAdapter);
}
}
}
Note that the use of weak reference above is to avoid context leaks (basically avoids unnecessary memory leaks).
You could also do this:
public void getData(String filter){
ParseQuery<ParseObject> query = ParseQuery.getQuery("Images");
query.whereEqualTo("category", filter);
query.findInBackground(new FindCallback<ParseObject>() {
public void done(List<ParseObject> downloads, com.parse.ParseException e) {
if (e == null) {
objectList=downloads;
int size = objectList.size();
for (int i = 0; i<size; i++){
ParseFile file = (ParseFile) objectList.get(i).get("Image");
urlList.add(file.getUrl());
}
RecyclerView recyclerView = (RecyclerView) view.findViewById(R.id.rv);
LinearLayoutManager linearLayoutManager = new LinearLayoutManager(getActivity());
recyclerView.setLayoutManager(linearLayoutManager);
MyAdapter myAdapter = new MyAdapter(urlList);
recyclerView.setAdapter(myAdapter);
} else {
Log.d("score", "Error: " + e.getMessage());
}
}
});
}

Change objectList=downloads to objectList.addAll(downloads) and add objectList = new ArrayList<>() in the first line.
Also move the section starting fromobjectList.size() inside the done method of query callback

Related

DialogFragment call failed

When you click on the CardView, a DialogFragment should appear, but the application crashes, writes the following in the logs
Process: com.example.testfuntura, PID: 15385
java.lang.ClassCastException: android.view.ContextThemeWrapper cannot be cast to androidx.appcompat.app.AppCompatActivity
at com.example.testfuntura.Attraction.AdapterAttractionsPackageOffer.lambda$onBindViewHolder$0(AdapterAttractionsPackageOffer.java:56)
at com.example.testfuntura.Attraction.-$$Lambda$AdapterAttractionsPackageOffer$4cZEQxk2beWA40yZmNkr6ZJp7o8.onClick(lambda)
at android.view.View.performClick(View.java:5692)
at android.view.View$PerformClick.run(View.java:22596)
My Adapter
public class AdapterAttractionsPackageOffer extends RecyclerView.Adapter<AdapterAttractionsPackageOffer.AttractionsViewHolderPackageOffer> {
public ArrayList<ItemPOA> mFavList;
public AdapterAttractionsPackageOffer(ArrayList<ItemPOA> favList) {
mFavList = favList;
}
#NonNull
#Override
public AttractionsViewHolderPackageOffer onCreateViewHolder(ViewGroup parent, int viewType) {
View v = LayoutInflater.from(parent.getContext()).inflate(R.layout.card_attraction_package_offer, parent, false);
return new AttractionsViewHolderPackageOffer(v);
}
public static class AttractionsViewHolderPackageOffer extends RecyclerView.ViewHolder {
public ImageView card_image_1;
public TextView Package_offer_title;
public CardView Card;
public AttractionsViewHolderPackageOffer(View itemView) {
super(itemView);
Card = itemView.findViewById(R.id.att_po);
card_image_1 = itemView.findViewById(R.id.img_po);
Package_offer_title = itemView.findViewById(R.id.tex);
}
}
#SuppressLint("LongLogTag")
#Override
public void onBindViewHolder(AttractionsViewHolderPackageOffer holder, int position) {
ItemPOA currentItem = mFavList.get(position);
holder.Package_offer_title.setText(currentItem.get_Package_offer_title());
holder.Card.setOnClickListener(v -> {
DialogPOA dialog = new DialogPOA();
dialog.show(((AppCompatActivity) v.getContext()).getSupportFragmentManager(), "item");
Bundle bundle1 = new Bundle();
bundle1.putString("title_po", currentItem.get_Package_offer_title());
bundle1.putString("description_po", currentItem.get_Package_offer_description());
bundle1.putString("cost_po", currentItem.get_Package_offer_cost());
dialog.setArguments(bundle1);
});
holder.getAdapterPosition();
}
#Override
public int getItemCount() {
return mFavList.size();
}
}
I have a similar Adapter, but when called, everything works, that is, the problem is not in the DialogFragment, since everything works when called from another fragment.
Fragment that the CardView is in
public class FragmentAtt extends Fragment {
ArrayList<ItemPOA> mFavList;
String URL = "http://qqqqqqqqq.mcdir.ru/dbpo.php";
RecyclerView mRec;
RecyclerView.LayoutManager recyclerViewlayoutManager;
RecyclerView.Adapter recyclerViewadapter;
//ImageView GET_PO_IMG;
String GET_PO_TITLE = "title_po";
String GET_PO_DESCRIPTION = "description_po";
String GET_PO_COST = "cost_po";
RequestQueue requestQueue;
JsonArrayRequest jsonArrayRequest;
#Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setRetainInstance(true);
}
#Override
public View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState) {
View view = inflater.inflate(R.layout.fragment_test_attraction, container, false);
TabLayout tabLayout = view.findViewById(R.id.tab);
ViewPager viewPager = view.findViewById(R.id.pager);
setupViewPager(viewPager);
tabLayout.setupWithViewPager(viewPager);
return view;
}
#Override
public void onViewCreated(#NonNull final View view, #Nullable Bundle savedInstanceState) {
mRec = requireView().findViewById(R.id.rec_po);
mFavList = new ArrayList<>();
recyclerViewadapter = new AdapterAttractionsPackageOffer(mFavList);
recyclerViewlayoutManager = new LinearLayoutManager(getContext());
mRec.setHasFixedSize(true);
mRec.setLayoutManager(recyclerViewlayoutManager);
mRec.setAdapter(recyclerViewadapter);
JSON_DATA_WEB_CALL2_RINK();
//recyclerViewlayoutManager = new LinearLayoutManager(getActivity(), LinearLayoutManager.HORIZONTAL, false);
//SnapHelper snapHelper = new GravitySnapHelper(Gravity.START);
//snapHelper.attachToRecyclerView(mRec);
}
private void setupViewPager(ViewPager viewPager) {
PagerAdapter adapter = new PagerAdapter(getChildFragmentManager());
adapter.addFragment(new FragmentAttractionRecyclerView(), "Аттракционы");
adapter.addFragment(new FragmentAttractionRecyclerView(), "Видеоигры");
viewPager.setAdapter(adapter);
}
public void JSON_DATA_WEB_CALL2_RINK() {
jsonArrayRequest = new JsonArrayRequest(URL,
this::JSON_PARSE_DATA_AFTER_WEBCALL_RINK,
error ->
Log.e("Volley", error.toString())) {
#Override
protected Response<JSONArray> parseNetworkResponse(NetworkResponse response) {
try {
Cache.Entry cacheEntry = HttpHeaderParser.parseCacheHeaders(response);
if (cacheEntry == null) {
cacheEntry = new Cache.Entry();
}
final long cacheExpired = 24 * 60 * 60 * 1000; // in 24 hours this cache entry expires completely
long now = System.currentTimeMillis();
final long ttl = now + cacheExpired;
cacheEntry.data = response.data;
cacheEntry.softTtl = now;
cacheEntry.ttl = ttl;
String headerValue;
headerValue = response.headers.get("Date");
if (headerValue != null) {
cacheEntry.serverDate = HttpHeaderParser.parseDateAsEpoch(headerValue);
}
headerValue = response.headers.get("Last-Modified");
if (headerValue != null) {
cacheEntry.lastModified = HttpHeaderParser.parseDateAsEpoch(headerValue);
}
cacheEntry.responseHeaders = response.headers;
final String jsonString = new String(response.data,
HttpHeaderParser.parseCharset(response.headers));
return Response.success(new JSONArray(jsonString), cacheEntry);
} catch (UnsupportedEncodingException | JSONException e) {
return Response.error(new ParseError(e));
}
}
};
requestQueue = Volley.newRequestQueue(requireContext());
requestQueue.add(jsonArrayRequest);
}
public void JSON_PARSE_DATA_AFTER_WEBCALL_RINK(JSONArray array) {
mFavList.clear();
for (int i = 0; i < array.length(); i++) {
ItemPOA GetDataAdapter2 = new ItemPOA();
JSONObject json;
try {
json = array.getJSONObject(i);
GetDataAdapter2.set_Package_offer_title(json.getString(GET_PO_TITLE));
GetDataAdapter2.set_Package_offer_description(json.getString(GET_PO_DESCRIPTION));
GetDataAdapter2.set_Package_offer_cost(json.getString(GET_PO_COST));
} catch (JSONException e) {
e.printStackTrace();
}
mFavList.add(GetDataAdapter2);
}
recyclerViewadapter = new AdapterAttractionsPackageOffer(mFavList);
mRec.setAdapter(recyclerViewadapter);
}
}
An Adapter that has the same functionality, but why does it work, explain the difference?
public class AdapterSkatingRinkSchedule_2 extends RecyclerView.Adapter<AdapterSkatingRinkSchedule_2.SkatingRinkScheduleViewHolder> {
public ArrayList<ItemSkatingRinkSchedule_2> mSkatingRinkScheduleList;
public AdapterSkatingRinkSchedule_2(ArrayList<ItemSkatingRinkSchedule_2> SkatingRinkScheduleList) {
mSkatingRinkScheduleList = SkatingRinkScheduleList;
}
#NonNull
#Override
public SkatingRinkScheduleViewHolder onCreateViewHolder(ViewGroup parent, int viewType) {
View v = LayoutInflater.from(parent.getContext()).inflate(R.layout.card_srs, parent, false);
return new SkatingRinkScheduleViewHolder(v);
}
public static class SkatingRinkScheduleViewHolder extends RecyclerView.ViewHolder {
public TextView number_srs, start_time_srs, end_time_srs, cost_1_srs, cost_2_srs;
public LinearLayout ll_main;
public SkatingRinkScheduleViewHolder(View itemView) {
super(itemView);
ll_main = itemView.findViewById(R.id.ll_main);
number_srs = itemView.findViewById(R.id.number_srs);
start_time_srs = itemView.findViewById(R.id.start_time_srs);
end_time_srs = itemView.findViewById(R.id.end_time_srs);
cost_1_srs = itemView.findViewById(R.id.cost_1_srs);
cost_2_srs = itemView.findViewById(R.id.cost_2_srs);
}
}
#SuppressLint("LongLogTag")
#Override
public void onBindViewHolder(SkatingRinkScheduleViewHolder holder, int position) {
ItemSkatingRinkSchedule_2 currentItem = mSkatingRinkScheduleList.get(position);
holder.number_srs.setText(currentItem.get_session_number());
holder.start_time_srs.setText(currentItem.get_session_start());
holder.end_time_srs.setText(currentItem.get_session_end());
holder.cost_1_srs.setText(currentItem.get_weekdays());
holder.cost_2_srs.setText(currentItem.get_weekends_and_holidays());
holder.ll_main.setOnClickListener(v -> {
DialogSkatingRinkSchedule dialogSRS = new DialogSkatingRinkSchedule();
dialogSRS.show(((AppCompatActivity) v.getContext()).getSupportFragmentManager(), "item");
Bundle bundle2 = new Bundle();
bundle2.putString("number", currentItem.get_session_number());
bundle2.putString("start", currentItem.get_session_start());
bundle2.putString("end", currentItem.get_session_end());
bundle2.putString("w", currentItem.get_weekdays());
bundle2.putString("wah", currentItem.get_weekends_and_holidays());
dialogSRS.setArguments(bundle2);
});
holder.getAdapterPosition();
}
#Override
public int getItemCount() {
return mSkatingRinkScheduleList.size();
}
}

java.lang.ClassCastException: android.view.ContextThemeWrapper cannot be cast to androidx.appcompat.app.AppCompatActivity
Here you are casting a context to an AppCompatActivity but actually Activity is not a Context
You have two options to solve this:
First option: Create a listener interface between the activity/fragment that holds the RecyclerView, implement it in that activity, and trigger its callback within the CardView onClickListener onClick() callback.
Second option: Change the constructor signature of the AdapterAttractionsPackageOffer adapter to accept a FragmentManager instance; save it as a class field like below, and reflect that on the instantiation of the adapter
public class AdapterAttractionsPackageOffer extends RecyclerView.Adapter<AdapterAttractionsPackageOffer.AttractionsViewHolderPackageOffer> {
public ArrayList<ItemPOA> mFavList;
private FragmentManager fragmentMgr;
public AdapterAttractionsPackageOffer(ArrayList<ItemPOA> favList, FragmentManager fManger) {
mFavList = favList;
fragmentMgr = fManger;
}
//......... suppressed code
#SuppressLint("LongLogTag")
#Override
public void onBindViewHolder(AttractionsViewHolderPackageOffer holder, int position) {
ItemPOA currentItem = mFavList.get(position);
holder.Package_offer_title.setText(currentItem.get_Package_offer_title());
holder.Card.setOnClickListener(v -> {
DialogPOA dialog = new DialogPOA();
dialog.show(fragmentMgr, "item");
Bundle bundle1 = new Bundle();
bundle1.putString("title_po", currentItem.get_Package_offer_title());
bundle1.putString("description_po", currentItem.get_Package_offer_description());
bundle1.putString("cost_po", currentItem.get_Package_offer_cost());
dialog.setArguments(bundle1);
});
holder.getAdapterPosition();
}
//......... suppressed code
}

create recycler view in fragment?

i want create a fragment and have inside a recycler view for show products ...
but when i render it is show this error : RecyclerView: No adapter attached; skipping layout
below i copy my codes;
this code is for adapter class :
private ArrayList<Products> ProductsList;
private Context context;
public Adapter(ArrayList<Products> productsList, Context context) {
ProductsList = productsList;
this.context = context;
}
#Override
public MyHolder onCreateViewHolder(ViewGroup parent, int viewType) {
View v = LayoutInflater.from(context).inflate(R.layout.row_layout, parent, false);
return new MyHolder(v);
}
#Override
public void onBindViewHolder(MyHolder holder, final int position) {
Products products = ProductsList.get(position);
holder.txtName.setText(products.getName());
holder.txtPrice.setText("$ " + products.getPrice());
Picasso.get().load(Config.ipValue + "/images/" + products.getPhoto()).into(holder.imgV);
holder.imgV.setOnClickListener(new View.OnClickListener() {
#Override
public void onClick(View v) {
v.startAnimation(AnimationUtils.loadAnimation(context, android
.R.anim.slide_in_left));
}
});
}
#Override
public int getItemCount() {
return ProductsList.size();
}
class MyHolder extends RecyclerView.ViewHolder {
TextView txtName;
TextView txtPrice;
ImageView imgV;
public MyHolder(View itemView) {
super(itemView);
txtName = itemView.findViewById(R.id.rowTxtProductName);
txtPrice = itemView.findViewById(R.id.rowTxtPrice);
imgV = itemView.findViewById(R.id.rowImgProduct);
}
}
and this one for web api class :
public class WebApiHandler {
Context context;
String apiLink = "";
ArrayList<Products> products = new ArrayList<>();
public WebApiHandler(Context context) {
this.context = context;
}
void apiConnect(String type) {
switch (type) {
case "getproducts": {
apiLink = Config.getProductsWebApi;
break;
}
}
ProgressDialog dialog = ProgressDialog.show(context, "Connecting...",
"please wait", false, false);
StringRequest request = new StringRequest(Request.Method.POST,
apiLink, new Response.Listener<String>() {
#Override
public void onResponse(String response) {
dialog.dismiss();
showJson(response);
}
}, new Response.ErrorListener() {
#Override
public void onErrorResponse(VolleyError error) {
dialog.dismiss();
}
});
RequestQueue queue = Volley.newRequestQueue(context);
queue.add(request);
}
private void showJson(String response) {
products.clear();
try {
JSONObject jsonObject = new JSONObject(response);
JSONArray jsonArray = jsonObject.getJSONArray("response");
for (int i = 0; i < jsonArray.length(); i++) {
JSONObject object = jsonArray.getJSONObject(i);
String id = object.getString("id");
String name = object.getString("name");
String description = object.getString("description");
String price = object.getString("price");
String photo = object.getString("photo");
Products p = new Products(id, name, description, price, photo);
products.add(p);
}
} catch (JSONException e) {
e.printStackTrace();
}
VerticalFragment.productsArrayList = products;
IData iData = (IData) context;
iData.sendData();
}}
and my fragment code :
public class VerticalFragment extends Fragment implements IData {
RecyclerView rcVertical;
WebApiHandler webApiHandler;
static ArrayList<Products> productsArrayList = new ArrayList<>();
public VerticalFragment() {
}
#Override
public View onCreateView(LayoutInflater inflater, ViewGroup container,
Bundle savedInstanceState) {
View view = inflater.inflate(R.layout.fragment_vertical, container, false);
rcVertical = view.findViewById(R.id.rcVertical);
webApiHandler = new WebApiHandler(getContext());
webApiHandler.apiConnect("getproducts");
rcVertical.addOnItemTouchListener(new RecyclerTouchListener(getContext(), rcVertical,
new RecyclerTouchListener.ClickListener() {
#Override
public void onClick(View view, int position) {
ProductActivity.products = productsArrayList.get(position);
startActivity(new Intent(getContext(), ProductActivity.class));
}
#Override
public void onLongClick(View view, int position) {
}
}));
return view;
}
#Override
public void sendData() {
Adapter adapter = new Adapter(productsArrayList, getContext());
rcVertical.setLayoutManager(new LinearLayoutManager((getContext())));
rcVertical.setItemAnimator(new DefaultItemAnimator());
rcVertical.setAdapter(adapter);
}}
i should say i create a interface and have one method i say it sendData

This is a common error when there is no adapter attached to recyclerview upon showing recyclerview. It will not cause any harm to your app, but you could avoid it by setting empty adapter without data, and later when you get your data, provide it to your adapter and notify it
Edit - Example added
Create setter for your list in adapter. After that, in your fragment make adapter global and in onCreateView make instance of your adapter and attach it to recyclerview
adapter = new Adapter(new ArrayList<>(), getContext());
rcVertical.setAdapter(adapter);
...Initialize recyclerview...
And then in your sendData interface put your loaded values in it
adapter.setData(productsArrayList);
adapter.notifyDataSetChanged();

How to load AdMobs inside RecycleView after every 5th row?

I am trying to implement AdMobs to load ads, every 5th row but i am having a difficult time, as you can see from my screenshot ads are being loaded successfully but they're being loaded after every row. Can someone help me accomplish this? I already tried reading through post on stack overflow but none seems to help. Thank you in advance. image screenshot
Fragment
public class SectorPerformanceFragment extends Fragment {
private RecyclerView newsFeedRecycleView;
private SectorPerformanceAdapter mostActiveAdapter;
private RecyclerViewAdopter recyclerViewAdopter;
public static final int ITEMS_PER_AD = 9;
private RecyclerView.LayoutManager layoutManager;
private RequestQueue requestQueue;
private JSONObject stockDetails;
public static ArrayList<SectorPerformanceModel> mostActiveArrayList;
private RequestQueue requestQueues;
private ImageView backImage;
private View rootView;
private ProgressBar loadingProgressBar;
private TextView sectorNameTv;
#Nullable
#Override
public View onCreateView(#NonNull LayoutInflater inflater, #Nullable ViewGroup container, #Nullable Bundle savedInstanceState) {
rootView = inflater.inflate(R.layout.recycle_view_list_ui, container, false);
sectorNameTv = rootView.findViewById(R.id.sectorNameTv);
sectorNameTv.setText("Sector Performance");
loadingProgressBar = rootView.findViewById(R.id.loadingProgressBar);
backImage = rootView.findViewById(R.id.backImageView);
backImage.setOnClickListener(new View.OnClickListener() {
#Override
public void onClick(View v) {
getActivity().getSupportFragmentManager().popBackStack();
//
// Fragment generalMarketFragment = new BrowseFragment();
// FragmentManager fragmentManager = getActivity().getSupportFragmentManager();
// FragmentTransaction fragmentTransaction = fragmentManager.beginTransaction();
// fragmentTransaction.replace(R.id.fragment_container, generalMarketFragment);
// fragmentTransaction.addToBackStack(null);
// fragmentTransaction.commit();
}
});
requestQueues = Volley.newRequestQueue(getActivity());
findViewById();
mostActiveArrayList = new ArrayList<>();
initRecycleView();
retreiveBundleInformation();
return rootView;
}
#Override
public void onViewCreated(#NonNull View view, #Nullable Bundle savedInstanceState) {
super.onViewCreated(view, savedInstanceState);
}
private void findViewById() {
newsFeedRecycleView = rootView.findViewById(R.id.recylcle_view_list);
}
//set up RecycleVIew/listener to detect taps layout manager tels recycle view how to display the list.. without it, nothing shows up
public void initRecycleView() {
layoutManager = new LinearLayoutManager(getContext(), LinearLayoutManager.VERTICAL, false);
newsFeedRecycleView.setHasFixedSize(true);
newsFeedRecycleView.setLayoutManager(layoutManager);
//mostActiveAdapter = new SectorPerformanceAdapter(getContext(), mostActiveArrayList);
// recyclerViewAdopter = new RecyclerViewAdopter(getContext(),mostActiveArrayList);
//
// //newsFeedRecycleView.setAdapter(mostActiveAdapter);
// newsFeedRecycleView.setAdapter(recyclerViewAdopter);
}
//download news data stocknewsapi..
private void downloadStockList(String api) {
// Initialize a new JsonArrayRequest instance
JsonArrayRequest jsonArrayRequest = new JsonArrayRequest(
Request.Method.GET,
api,
null,
new Response.Listener<JSONArray>() {
#Override
public void onResponse(JSONArray response) {
// Do something with response
//mTextView.setText(response.toString());
loadingProgressBar.setVisibility(View.INVISIBLE);
//Log.i("jsonResponse", response.toString());
// Process the JSON
// Loop through the array elements
for (int i = 0; i < response.length(); i++) {
// Get current json object
try {
stockDetails = response.getJSONObject(i);
Log.i("stockDetails", stockDetails.toString());
SectorPerformanceModel sectorPerformanceModel2 = new SectorPerformanceModel(stockDetails.getString("sector"),stockDetails.getString("changesPercentage"),1);
mostActiveArrayList.add((sectorPerformanceModel2));
SectorPerformanceModel sectorPerformanceModel3 = new SectorPerformanceModel(stockDetails.getString("sector"),stockDetails.getString("changesPercentage"),2);
mostActiveArrayList.add(mostActiveArrayList.size(),sectorPerformanceModel3);
recyclerViewAdopter = new RecyclerViewAdopter(getContext(),mostActiveArrayList);
//newsFeedRecycleView.setAdapter(mostActiveAdapter);
newsFeedRecycleView.setAdapter(recyclerViewAdopter);
//recyclerViewAdopter.notifyDataSetChanged();
// mostActiveArrayList.add(sectorPerformanceModel);
// mostActiveAdapter.notifyDataSetChanged();
} catch (JSONException e) {
e.printStackTrace();
}
}
}
},
new Response.ErrorListener() {
#Override
public void onErrorResponse(VolleyError error) {
Log.i("error", error.toString());
}
}
);
// Add JsonArrayRequest to the RequestQueue
requestQueues.add(jsonArrayRequest);
}
public void retreiveBundleInformation() {
downloadStockList("APIKEY");
}
}
Adapter
[public class RecyclerViewAdopter extends RecyclerView.Adapter<RecyclerView.ViewHolder>{
private Context mContext;
private List<SectorPerformanceModel> mList;
public RecyclerViewAdopter(Context mContext, List<SectorPerformanceModel> mList) {
this.mList = mList;
this.mContext = mContext;
}
public static class MyViewHolder extends RecyclerView.ViewHolder {
public TextView name;
private TextView newsTitle, sourceName, epsEstiatmate;
private CircleImageView newsThumbImage;
public MyViewHolder(View view) {
super(view);
epsEstiatmate = itemView.findViewById(R.id.formTypeTv);
newsTitle = itemView.findViewById(R.id.tickerTv);
sourceName = itemView.findViewById(R.id.dateTv);
newsThumbImage= itemView.findViewById(R.id.defaultImageColor);
newsThumbImage.setOnClickListener(new View.OnClickListener() {
#Override
public void onClick(View v) {
Log.i("tapped","TAPPED");
}
});
}
}
public static class ViewHolderAdMob extends RecyclerView.ViewHolder {
public AdView mAdView;
public ViewHolderAdMob(View view) {
super(view);
mAdView = (AdView) view.findViewById(R.id.adView);
AdRequest adRequest = new AdRequest.Builder()
.addTestDevice(AdRequest.DEVICE_ID_EMULATOR)
.build();
mAdView.loadAd(adRequest);
}
}
#Override
public RecyclerView.ViewHolder onCreateViewHolder(ViewGroup parent, int viewType) {
RecyclerView.ViewHolder viewHolder = null;
LayoutInflater inflater = LayoutInflater.from(parent.getContext());
switch(viewType){
case 1:{
View v = inflater.inflate(R.layout.trending_stock_row, parent, false);
viewHolder = new MyViewHolder(v);
break;
}
case 2:{
View v = inflater.inflate(R.layout.ads_row, parent, false);
viewHolder = new ViewHolderAdMob(v);
break;
}
}
return viewHolder;
}
#Override
public void onBindViewHolder(final RecyclerView.ViewHolder holder, final int position) {
SectorPerformanceModel model= mList.get(holder.getAdapterPosition());
switch(holder.getItemViewType()){
case 1:{
MyViewHolder viewHolder = (MyViewHolder) holder;
Random r = new Random();
int red = r.nextInt(255 - 0 + 1) + 0;
int green = r.nextInt(255 - 0 + 1) + 0;
int blue = r.nextInt(255 - 0 + 1) + 0;
GradientDrawable draw = new GradientDrawable();
draw.setShape(GradientDrawable.OVAL);
draw.setColor(Color.rgb(red, green, blue));
viewHolder.newsThumbImage.setBackground(draw);
viewHolder.newsTitle.setText(model.getSector());
viewHolder.sourceName.setText(model.getChangesPercentage());
break;
}
case 2:{
break;
}
}
}
#Override
public int getItemViewType(int position) {
return mList.get(position).getViewType();
}
#Override
public int getItemCount() {
return mList.size();
}
}][1]

It looks like you are adding 2 items to your adapter's data source for each element in your API response: one element has viewType 1 and the other viewType 2:
SectorPerformanceModel sectorPerformanceModel2 = new SectorPerformanceModel(stockDetails.getString("sector"),stockDetails.getString("changesPercentage"),1);
mostActiveArrayList.add((sectorPerformanceModel2));
SectorPerformanceModel sectorPerformanceModel3 = new SectorPerformanceModel(stockDetails.getString("sector"),stockDetails.getString("changesPercentage"),2);
mostActiveArrayList.add(mostActiveArrayList.size(),sectorPerformanceModel3);
Your adapter is rendering items with viewType 2 as ad rows, so if you want to display an ad row every 5 rows you'll need to update the downloadStockList method to execute this
SectorPerformanceModel sectorPerformanceModel3 = new SectorPerformanceModel(stockDetails.getString("sector"),stockDetails.getString("changesPercentage"),2);
mostActiveArrayList.add(mostActiveArrayList.size(),sectorPerformanceModel3);
only after having added 4 items with viewType 1.

JSONArray data won't show on Fragment

I'm having problems with showing JSONArray data on the Fragment. I am verified my links, Strings etc. But on the Debug console my request showing correct. I am suspecting JSONArray request but i can't find any errors.
Please, help!
D/Request::: 010-8470-0486
010-8472-0964
010-8474-2372
D/Request::: 010-8475-0089
D/Request::: 010-8475-7585
010-8478-0007
D/Request::: 010-8478-0573
010-8479-0311
010-8479-9234
D/Request::: 010-8481-2030
This is my Fragment
public class FragmentDB extends Fragment {
private View v;
private RecyclerView recyclerView;
private String url = "http://www.example.com/api.php";
private List<ModelDB> modelDBList;
public FragmentDB() {
}
#SuppressWarnings("UnnecessaryLocalVariable")
#Nullable
#Override
public View onCreateView(#NonNull LayoutInflater inflater, #Nullable ViewGroup container, Bundle savedInstanceState) {
if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.M) {
if (Objects.requireNonNull(getActivity()).checkSelfPermission(Manifest.permission.READ_CALL_LOG) != PackageManager.PERMISSION_GRANTED &&
getActivity().checkSelfPermission(Manifest.permission.READ_CONTACTS) != PackageManager.PERMISSION_GRANTED &&
getActivity().checkSelfPermission(Manifest.permission.READ_PHONE_STATE) != PackageManager.PERMISSION_GRANTED)
return v;
} else {
Intent i10 = new Intent(getActivity(), PermissionActivity.class);
startActivity(i10);
Objects.requireNonNull(getActivity()).finish();
}
v = inflater.inflate(R.layout.frag_db, container, false);
recyclerView = v.findViewById(R.id.rv_db);
LinearLayoutManager linearLayoutManager = new LinearLayoutManager(getContext());
RecyclerView.LayoutManager layoutManager = linearLayoutManager;
recyclerView.setLayoutManager(layoutManager);
DividerItemDecoration dividerItemDecoration = new DividerItemDecoration(recyclerView.getContext(), linearLayoutManager.getOrientation());
modelDBList = new ArrayList<>();
DbRvAdapter adapter = new DbRvAdapter(getContext(), modelDBList);
recyclerView.setAdapter(adapter);
adapter.notifyDataSetChanged();
recyclerView.addItemDecoration(dividerItemDecoration);
recyclerView.setHasFixedSize(true);
Objects.requireNonNull(getActivity()).getWindow().setSoftInputMode(WindowManager.LayoutParams.SOFT_INPUT_STATE_ALWAYS_HIDDEN);
getDBLogs();
return v;
}
#SuppressWarnings({"LogNotTimber", "deprecation"})
private void getDBLogs() {
JsonArrayRequest jsonArrayRequest = new JsonArrayRequest(url, new Response.Listener<JSONArray>() {
#Override
public void onResponse(JSONArray response) {
// Do something with the response
try {
for ( int i = 0; i < response.length(); i++) {
JSONObject obj = response.getJSONObject(i);
ModelDB dblist = new ModelDB();
dblist.setPhone_number(obj.getString("phone_number"));
dblist.setInfo1(obj.getString("info1"));
modelDBList.add(dblist);
Log.d("Request:: ", obj.getString("phone_number"));
}
} catch(JSONException e) {
e.printStackTrace();
}
}
}, new Response.ErrorListener() {
#Override
public void onErrorResponse(VolleyError error) {
// Handle error
Log.e("Volley", error.toString());
}
});
RequestQueue rq = Volley.newRequestQueue(Objects.requireNonNull(getActivity()).getApplicationContext());
rq.add(jsonArrayRequest);
}
}
and ModelDB class
public class ModelDB {
public String phone_number;
public String info1;
public ModelDB() {
}
public ModelDB(String phone_number, String info1) {
this.phone_number = phone_number;
this.info1 = info1;
}
public String getPhone_number() {
return phone_number;
}
public void setPhone_number(String phone_number) {
this.phone_number = phone_number;
}
public String getInfo1() {
return info1;
}
public void setInfo1(String info1) {
this.info1 = info1;
}
}
and adapter class
public class DbRvAdapter extends RecyclerView.Adapter<DbRvAdapter.ViewHolder> {
public static final String KEY_DBPHONENUMBER = "phone_number";
public static final String KEY_DBINFO = "info1";
private Context context;
private List<ModelDB> list;
public DbRvAdapter(Context context, List<ModelDB> list) {
this.context = context;
this.list = list;
}
#NonNull
#Override
public ViewHolder onCreateViewHolder(#NonNull ViewGroup parent, int viewType) {
View v = LayoutInflater.from(parent.getContext()).inflate(R.layout.single_db, parent, false);
return new ViewHolder(v);
}
#SuppressWarnings("RecyclerView")
#Override
public void onBindViewHolder(#NonNull ViewHolder holder, final int position) {
final ModelDB modelDB = list.get(position);
holder.textDBP.setText(modelDB.getPhone_number());
holder.textInfo1.setText(String.valueOf(modelDB.getInfo1()));
holder.relativeLayout.setOnClickListener(new View.OnClickListener() {
#Override
public void onClick(View v) {
ModelDB modelDB1 = list.get(position);
Intent skipIntent = new Intent(v.getContext(), NumberActivity.class);
skipIntent.putExtra(KEY_DBINFO, modelDB1.getInfo1());
skipIntent.putExtra(KEY_DBPHONENUMBER, modelDB1.getPhone_number());
v.getContext().startActivity(skipIntent);
}
});
}
#Override
public int getItemCount() {
return list.size();
}
public class ViewHolder extends RecyclerView.ViewHolder {
public TextView textDBP, textInfo1;
public RelativeLayout relativeLayout;
public ViewHolder(View itemView) {
super(itemView);
textDBP = itemView.findViewById(R.id.tv_number);
textInfo1 = itemView.findViewById(R.id.tv_dbinfo);
}
}
}
Sorry for my bad English.

notify you adapter after the for loop body and declare the adapter globally
for ( int i = 0; i < response.length(); i++) {
............
modelDBList.add(dblist);
}
if(dblist != null and dblist.size() > 0){
adapter.notifyDataSetChanged();
}

It looks like you didn't update list of modelDB's inside adapter after the parsing of a network call result.

New fetch data is not show on recycler list when pull down to refresh

I want to implement one code where data will come on Scroll and if the data is add on list then we pull down(SwipeRefreshLayout) the new data will come on that list. In my below code the add on data is coming in response but not come in list? I have read many tutorials like this but data is coming on Swipe refresh but not shown on list. Thank you in advance
public class UpdatesFragment extends Fragment implements SwipeRefreshLayout.OnRefreshListener{
SwipeRefreshLayout mSwipeRefreshLayout;
UserSessionManager session;
private List<SuperHero> listSuperHeroes;
private RecyclerView recyclerView;
private RecyclerView.LayoutManager layoutManager;
private RecyclerView.Adapter adapter;
public ProgressBar progressBar;
public String user_id;
TextView textView;
FloatingActionButton fab;
public int a=1;
#Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
}
#Override
public View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState) {
View view= inflater.inflate(R.layout.fragment_updates, container, false);
session = new UserSessionManager(getActivity());
// get user data from session
HashMap<String, String> user = session.getUserDetails();
user_id = user.get(UserSessionManager.KEY_USER_ID);
// SwipeRefreshLayout
mSwipeRefreshLayout = (SwipeRefreshLayout) view.findViewById(R.id.swipe_container);
mSwipeRefreshLayout.setOnRefreshListener(this);
mSwipeRefreshLayout.setColorSchemeResources(R.color.colorPrimary,
android.R.color.holo_green_dark,
android.R.color.holo_orange_dark,
android.R.color.holo_blue_dark);
/**
* Showing Swipe Refresh animation on activity create
* As animation won't start on onCreate, post runnable is used
*/
mSwipeRefreshLayout.post(new Runnable() {
#Override
public void run() {
mSwipeRefreshLayout.setRefreshing(true);
// Fetching data from server
getDataFromServer(1);
}
});
return view;
}
public void onViewCreated(View v, Bundle savedInstanceState) {
super.onViewCreated(v, savedInstanceState);
fab = (FloatingActionButton)v.findViewById(R.id.fab);
recyclerView = (RecyclerView) v.findViewById(R.id.updatesRecycler);
recyclerView.setHasFixedSize(true);
layoutManager = new LinearLayoutManager(getContext());
recyclerView.setLayoutManager(layoutManager);
listSuperHeroes = new ArrayList<>();
adapter = new CardAdapter(listSuperHeroes, getActivity());
recyclerView.setAdapter(adapter);
textView = (TextView)v.findViewById(R.id.text);
fab.setOnClickListener(new View.OnClickListener() {
#Override
public void onClick(View v) {
Intent i = new Intent(getContext(), AddWebPostActivity.class);
startActivity(i);
}
});
getDataFromServer(a);
recyclerView.setOnScrollListener(new EndlessRecyclerOnScrollListener((LinearLayoutManager) layoutManager) {
#Override
public void onLoadMore(int current_page) {
getDataFromServer(current_page);
}
});
}
public void getDataFromServer(int requestCount) {
Log.e("count",String.valueOf(requestCount));
final String DATA_URL = "https://XYZ.php?username="+user_id + "&page="+requestCount;
JsonArrayRequest jsonArrayRequest = new JsonArrayRequest(DATA_URL,
new Response.Listener<JSONArray>() {
#Override
public void onResponse(JSONArray response) {
mSwipeRefreshLayout.setRefreshing(false);
Log.e("URL___________",DATA_URL);
Log.e("response___________", String.valueOf(response));
parseData(response);
adapter.notifyDataSetChanged();
}
},
new Response.ErrorListener() {
#Override
public void onErrorResponse(VolleyError error) {
Toast.makeText(getContext(), "No More Items Available", Toast.LENGTH_SHORT).show();
}
});
RequestQueue requestQueue = Volley.newRequestQueue(getContext());
requestQueue.getCache().clear();
requestQueue.add(jsonArrayRequest);
}
private void parseData(JSONArray array) {
for (int i = 0; i < array.length(); i++) {
SuperHero superHero = new SuperHero();
JSONObject json = null;
try {
json = array.getJSONObject(i);
superHero.setPost_title(json.getString(Config.TAG_POST_TITLE));
superHero.setPost_content(json.getString(Config.TAG_POST_CONTENT));
superHero.setPost_parent(json.getString(Config.TAG_POST_PARENT));
superHero.setPost_date(json.getString(Config.TAG_POST_DATE));
superHero.setPost_date_gmt(json.getString(Config.TAG_POST_DATE_GMT));
superHero.setScheduled_date(json.getString(Config.TAG_SCHEDULED_DATE));
superHero.setTo_ping(json.getString(Config.TAG_IP_ADDRESS));
superHero.setVisit_post(json.getString(Config.TAG_VISIT_POST));
superHero.setUr_id(json.getString(Config.TAG_UR_ID));
} catch (JSONException e) {
e.printStackTrace();
}
listSuperHeroes.add(superHero);
}
}
/**
* Called when a swipe gesture triggers a refresh.
*/
#Override
public void onRefresh() {
getDataFromServer(1);
}
}
Adapter
public class CardAdapter extends RecyclerView.Adapter<CardAdapter.ViewHolder> {
UserSessionManager session;
public String user_id;
public String ur_id;
private Context context;
//String visit;
//List to store all superheroes
List<SuperHero> superHeroes;
//Constructor of this class
public CardAdapter(List<SuperHero> superHeroes, Context context){
super();
//Getting all superheroes
this.superHeroes = superHeroes;
this.context = context;
}
#Override
public ViewHolder onCreateViewHolder(ViewGroup parent, int viewType) {
View v = LayoutInflater.from(parent.getContext())
.inflate(R.layout.web_post, parent, false);
// Session class instance
session = new UserSessionManager(context);
session.checkLogin();
// get user data from session
HashMap<String, String> user = session.getUserDetails();
user_id = user.get(UserSessionManager.KEY_USER_ID);
ViewHolder viewHolder = new ViewHolder(v);
return viewHolder;
}
#Override
public void onBindViewHolder(final ViewHolder holder, final int position) {
//Getting the particular item from the list
final SuperHero superHero = superHeroes.get(position);
holder.tvPostTitle.setText(superHero.getPost_title());
holder.tvPostContent.setText(superHero.getPost_content());
holder.tvPostDateTime1.setText(superHero.getPost_date() +" / " +superHero.getPost_date_gmt());
final String visit = superHero.getVisit_post();
holder.tvVisitPost.setOnClickListener(new View.OnClickListener() {
#Override
public void onClick(View view) {
Intent i = new Intent(context,VisitWebView.class);
i.putExtra("visitURL",visit);
context.startActivity(i);
}
});
}
#Override
public int getItemCount() {
return superHeroes.size();
}
#Override
public int getItemViewType(int position) {
return position;
}
class ViewHolder extends RecyclerView.ViewHolder{
//Views
public TextView tvPostTitle,tvPostContent,tvPostDateTime1,tvVisitPost;
public ImageButton removeButton;
//Initializing Views
public ViewHolder(final View itemView) {
super(itemView);
tvPostTitle = (TextView) itemView.findViewById(R.id.tvPostTitle);
tvPostContent = (TextView) itemView.findViewById(R.id.tvPostContent);
tvPostDateTime1 = (TextView) itemView.findViewById(R.id.tvPostDateTime1);
tvVisitPost = (TextView) itemView.findViewById(R.id.tvVisitPost);
removeButton = (ImageButton) itemView.findViewById(R.id.removeButton);
}
}
}

use this method
mSwipeRefreshLayout.setOnRefreshListener(new SwipeRefreshLayout.OnRefreshListener() {
#Override
public void onRefresh() {
mSwipeRefreshLayout.setRefreshing(true);
getDataFromServer(1);
}
instead of this
mSwipeRefreshLayout.post(new Runnable() {
#Override
public void run() {
mSwipeRefreshLayout.setRefreshing(true);
// Fetching data from server
getDataFromServer(1);
}
});

Please call adapter and pass fresh list data after this line
listSuperHeroes.add(superHero) in parseData(response) function ;
adapter = new CardAdapter(listSuperHeroes, getActivity());
recyclerView.setAdapter(adapter)
adapter.notifyDataSetChanged();

Develop Reference

Java is a programming language and computing platform first released by Sun Microsystems in 1995.

ParseQuery NullPointer Exception Paradox - java

Change objectList=downloads to objectList.addAll(downloads) and add objectList = new ArrayList<>() in the first line. Also move the section starting fromobjectList.size() inside the done method of query callback

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JSONArray data won't show on Fragment

New fetch data is not show on recycler list when pull down to refresh

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