Develop Reference

Passing data in recycler view from API

I tried to make a covid-19 tracking app by watching Youtube tutorials.
My app shows the country list with flags and when you click on any country it opens an activity and shows the details of that country i.e total cases, deaths, recovered, etc. The video on Youtube uses ListView and I am using recyclerView
I fetched the country list successfully and set onClickListener on the view and it opens second activity which shows the case in detail. But I don't know how to show the data.
my adapter class:
class Countries_adapter extends RecyclerView.Adapter<Countries_adapter.MyViewHolder> {
Context ct;
List<Countries_data> list;
public Countries_adapter(Context context,List<Countries_data> country)
{
ct=context;
list=country;
}
#Override
public MyViewHolder onCreateViewHolder( ViewGroup parent, int viewType) {
View v = LayoutInflater.from(ct).inflate(R.layout.countries_row,parent,false);
return new MyViewHolder(v);
}
#Override
public void onBindViewHolder(MyViewHolder holder, final int position) {
holder.tvCountryName.setText(list.get(position).getCountry());
holder.tvtotal.setText(list.get(position).getActive());
Glide.with(ct).load(list.get(position).getFlag()).into(holder.imageView);
holder.linearLayout.setOnClickListener(new View.OnClickListener() {
#Override
public void onClick(View view) {
Intent i = new Intent(ct,CountriesDetails.class);
i.putExtra("Country",list.get(position).getCountry());
ct.startActivity(i);
}
});
}
#Override
public int getItemCount() {
return list.size();
}
public class MyViewHolder extends RecyclerView.ViewHolder {
TextView tvCountryName,tvtotal;
ImageView imageView;
LinearLayout linearLayout;
public MyViewHolder( View itemView) {
super(itemView);
tvCountryName = itemView.findViewById(R.id.tvCountryName);
tvtotal=itemView.findViewById(R.id.tvCountrytotalcaese);
imageView = itemView.findViewById(R.id.imageFlag);
linearLayout=itemView.findViewById(R.id.linear_layout);
}
}
my AffectedCoutries class activity is as follows:
public class AffectedCountries extends AppCompatActivity {
EditText edtSearch;
RecyclerView recyclerView;
SimpleArcLoader simpleArcLoader;
public static ArrayList countryList = new ArrayList<>();
Countries_data countryData;
Countries_adapter CountriesAdapter;
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_affected_countries);
edtSearch = findViewById(R.id.edtSearch);
recyclerView=findViewById(R.id.recyclerAffectedCountries);
simpleArcLoader = findViewById(R.id.loader);
fetchData();
}
private void fetchData() {
String url = "https://corona.lmao.ninja/v2/countries/";
simpleArcLoader.start();
StringRequest request = new StringRequest(Request.Method.GET, url,
new Response.Listener<String>() {
#Override
public void onResponse(String response) {
try {
JSONArray jsonArray = new JSONArray(response);
for(int i=0;i<jsonArray.length();i++){
JSONObject jsonObject = jsonArray.getJSONObject(i);
String countryName = jsonObject.getString("country");
String cases = jsonObject.getString("cases");
String todayCases = jsonObject.getString("todayCases");
String deaths = jsonObject.getString("deaths");
String todayDeaths = jsonObject.getString("todayDeaths");
String recovered = jsonObject.getString("recovered");
String active = jsonObject.getString("active");
String critical = jsonObject.getString("critical");
JSONObject object = jsonObject.getJSONObject("countryInfo");
String flagUrl = object.getString("flag");
countryData = new Countries_data(flagUrl,countryName,cases,todayCases,deaths,todayDeaths,recovered,active,critical);
countryList.add(countryData);
}
CountriesAdapter = new Countries_adapter(AffectedCountries.this,countryList);
recyclerView.setLayoutManager(new LinearLayoutManager(AffectedCountries.this));
recyclerView.setAdapter(CountriesAdapter);
simpleArcLoader.stop();
simpleArcLoader.setVisibility(View.GONE);
} catch (JSONException e) {
e.printStackTrace();
simpleArcLoader.start();
simpleArcLoader.setVisibility(View.GONE);
Toast.makeText(AffectedCountries.this,"catch response", Toast.LENGTH_SHORT).show();
}
}
}, new Response.ErrorListener() {
#Override
public void onErrorResponse(VolleyError error) {
simpleArcLoader.stop();
simpleArcLoader.setVisibility(View.GONE);
Toast.makeText(AffectedCountries.this,"error response", Toast.LENGTH_SHORT).show();
}
});
RequestQueue requestQueue = Volley.newRequestQueue(this);
requestQueue.add(request);
}
}
my Countries_data class(model class)
public class Countries_data {
public String country;
public String cases;
public String todayCases;
public String deaths;
public String todayDeaths;
public String recovered;
public String active;
public String critical;
public String flag;
public Countries_data(String flag, String country, String cases, String
todayCases, String deaths, String todayDeaths, String recovered,
String active, String critical) {
this.country = country;
this.cases = cases;
this.todayCases = todayCases;
this.deaths = deaths;
this.todayDeaths = todayDeaths;
this.recovered = recovered;
this.active = active;
this.critical = critical;
this.flag = flag;
}
public String getCountry() {
return country;
}
public void setCountry(String country) {
this.country = country;
}
public String getCases() {
return cases;
}
public void setCases(String cases) {
this.cases = cases;
}
public String getTodayCases() {
return todayCases;
}
public void setTodayCases(String todayCases) {
this.todayCases = todayCases;
}
public String getDeaths() {
return deaths;
}
public void setDeaths(String deaths) {
this.deaths = deaths;
}
public String getTodayDeaths() {
return todayDeaths;
}
public void setTodayDeaths(String todayDeaths) {
this.todayDeaths = todayDeaths;
}
public String getRecovered() {
return recovered;
}
public void setRecovered(String recovered) {
this.recovered = recovered;
}
public String getActive() {
return active;
}
public void setActive(String active) {
this.active = active;
}
public String getCritical() {
return critical;
}
public void setCritical(String critical) {
this.critical = critical;
}
public String getFlag() {
return flag;
}
public void setFlag(String flag) {
this.flag = flag;
}
}
my Country_details class
public class CountriesDetails extends AppCompatActivity {
TextView tvCountry, tvCases, tvRecovered,tvdeaths;
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_countries_details2);
tvCountry = findViewById(R.id.tvCountry);
tvCases = findViewById(R.id.tvCases);
tvRecovered = findViewById(R.id.tvRecovered);
tvdeaths=findViewById(R.id.tvTotalDeaths);
String positionCountry = getIntent().getStringExtra("Country");
Log.i("country name", positionCountry);
}
}
How to set the data in tvcases?
How can I show the data? Do I have to create a separate recycler view and then fetch the data from the API or can I use my main activity to show the data?

I have some sad information for you: Google Play policy restricts such apps from being published in store... especially when you are showing deaths count. Been there, done that, my app was blocked...
besides above:
you are passing country name in intent:
i.putExtra("Country",list.get(position).getCountry());
but trying to read "position" in details Activity - it will be always 0 (default)
edit due to comments:
pass position of clicked View
holder.linearLayout.setOnClickListener(new View.OnClickListener() {
#Override
public void onClick(View view) {
Intent i = new Intent(ct,CountriesDetails.class);
i.putExtra("position", position);
ct.startActivity(i);
}
});
in CountriesDetailss onCreate method receive this position and restore proper Countries_data object from your static countryList array in AffectedCountries
int position = getIntent().getIntExtra("position", 0);
Countries_data country = AffectedCountries.countryList.get(position);
tvCountry.setText(country.getCountry());
that should work, but this isn't best way to store data, in fact its very weak... after downloading data (list of countries) you should store it somehow, e.g. SQLite/Room lib or at least SharedPreferences... then in details activity you should restore int position and using it take proper object from database or preferences, instead of stright from static array
it may be also useful to implement Parcelable inteface to your Countries_data - this will allow to put whole Countries_data object into Intents extras, not only primitive int with position in array. in this case details activity won't even need access to whole array or sql database/preferences, it will get whole object straight from Intents extras

get TextView from another class

I want to display this textview "txtCalculate" which comes from the class CustomerMapActivity which is displayed in the activity_map_customer layout in another layout which is activity_bon_de_commande, of the class BonDeCommande.
the problem is I don't know how to do it
I'm new to java programming
thank you
public void readValues(){
DatabaseReference ref = FirebaseDatabase.getInstance().getReference();
Query lastQuery = ref.child("ride_info").orderByKey().limitToLast(1);
lastQuery.addListenerForSingleValueEvent(new ValueEventListener() {
#Override
public void onDataChange(DataSnapshot dataSnapshot) {
for(DataSnapshot ds : dataSnapshot.getChildren()){
double value0_float = ds.child("pickup").child("lat").getValue(Double.class);
double value1_float = ds.child("pickup").child("lng").getValue(Double.class);
double value2_float = ds.child("destination").child("lat").getValue(Double.class);
double value3_float = ds.child("destination").child("lng").getValue(Double.class);
String pickupLat = String.valueOf(value0_float);
String pickupLng = String.valueOf(value1_float);
String destiLat = String.valueOf(value2_float);
String destiLng = String.valueOf(value3_float);
String requestUrl=null;
try {
requestUrl = "https://maps.googleapis.com/maps/api/directions/json?"+
"mode=driving&"
+"transit_routing_preference=less_driving&"
+"origin="+pickupLat+","+pickupLng+"&"
+"destination="+destiLat+","+destiLng+"&"
+"key="+getResources().getString(R.string.google_maps_key);
Log.e("LINK",requestUrl);
mService.getPath(requestUrl).enqueue(new Callback<String>() {
#Override
public void onResponse(Call<String> call, Response<String> response) {
try {
JSONObject jsonObject = new JSONObject(response.body().toString());
JSONArray routes = jsonObject.getJSONArray("routes");
JSONObject object = routes.getJSONObject(0);
JSONArray legs = object.getJSONArray("legs");
JSONObject legsObject = legs.getJSONObject(0);
//Get distance
JSONObject distance = legsObject.getJSONObject("distance");
String distance_text = distance.getString("text");
//use regex to extract double from string
//This regex will remove all text not digit
Double distance_value= Double.parseDouble(distance_text.replaceAll("[^0-9\\\\.]+",""));
//Get Time
JSONObject time = legsObject.getJSONObject("duration");
String time_text = time.getString("text");
Integer time_value = Integer.parseInt(time_text.replaceAll("\\D+",""));
String final_calculate = String.format("%.2f €",
TypeObject.getPrice(distance_value,time_value));
HERE -----> txtCalculate.setText(final_calculate);
} catch (JSONException e) {
e.printStackTrace();
}
}
#Override
public void onFailure(Call<String> call, Throwable t) {
mCurrentRide.cancelRide();
endRide();
}
});
}
catch (Exception ex)
{
ex.printStackTrace();
}
}
}
#Override
public void onCancelled(DatabaseError databaseError) {
mCurrentRide.cancelRide();
endRide();
}
});
}
screenshot of my screen

You need to Create an Interface with an update method, declare in your Activity and after, pass as parameter to your handler object that gets the data.
Don't forget If you're getting the data in a different Thread, you need to update your views always in an UI Thread or in the Main Thread.
Here Follow some example code:
Your Activity or Fragment
public class MainActivity extends AppCompatActivity
implements UpdateViewCallback { // implement the interface here
private TextView textView = null;
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
Toolbar toolbar = findViewById(R.id.toolbar);
setSupportActionBar(toolbar);
textView = findViewById(R.id.textView);
// Pass the interface in your Object that makes the async work
final AsyncWork asyncWork = new AsyncWork(this);
// Running
Thread thread = new Thread(asyncWork);
thread.start();
}
/**
* UpdateViewCallback
* #param result
*/
#Override
public void updateView(final String result) {
// Always update View on MainThread or an UI Thread, or else issues will start to happening
this.runOnUiThread(new Runnable() {
public void run() {
// Check if View is null since you're updating in a thread async
if (textView != null) {
textView.setText(result);
}
}
});
}
}
Your Interface:
public interface UpdateViewCallback {
void updateView(String result);
}
Your Object to handle the Async Work:
public class AsyncWork implements Runnable {
private UpdateViewCallback updateViewCallback;
public AsyncWork(UpdateViewCallback updateViewCallback) {
this.updateViewCallback = updateViewCallback;
}
/**
* Async Work here
*/
#Override
public void run() {
// Do some Work and after update using the interface you passed in the constructor
updateViewCallback.updateView("This is a test");
}
}

unable to set drawable on ImageView in HandlerThread subclass

i am writing a flickr client as part of a project from a book that i am reading. in it i create a subclass of HandlerThread that downloads images from flickr and then sets them in an ImageView. i set a placeholder .png earlier in the program and this binds (but with delay) however when i try to replace it nothing happens. the placeholder stays there and is not replaced. it seems like something is happening between that is preventing my HandlerThread from running properly. i have tried stepping through this with the debugger and also looking through the logcat however the logcat has been particularly unhelpful ever since the last update to android studio. it works partially if at all. so right i am getting no error message. earlier i got one stating that i had a null pointer exception but i wasnt able to see where it had come from and upon running the application again it was gone. i am posting samples of my code including the main Fragment which serves as the UI Thread, and the ThumbnailDownloader class which is my HandlerThread subclass.
public class PhotoGalleryFragment extends Fragment {
private static final String TAG = "PhotoGalleryFragment";
private RecyclerView mRecyclerView;
private List<GalleryItem> mItems = new ArrayList<>();
private ThumbnailDownloader<PhotoHolder> mThumbnailDownloader;
public static PhotoGalleryFragment newInstance(){
return new PhotoGalleryFragment();
}
#Override
public void onCreate(Bundle savedInstanceState){
super.onCreate(savedInstanceState);
setRetainInstance(true);
new FetchItemsTask().execute();
Handler responseHandler = new Handler();
mThumbnailDownloader = new ThumbnailDownloader<>(responseHandler);
mThumbnailDownloader.setThumbnailDownloadListener( new ThumbnailDownloader.ThumbnailDownloadListener<PhotoHolder>() {
#Override
public void onThumbnailDownloaded(PhotoHolder target, Bitmap bitmap) {
Log.i(TAG, "setThumbnailDownloadListener() called!");
Drawable drawable = new BitmapDrawable(getResources(), bitmap);
target.bindDrawable(drawable);
}
});
mThumbnailDownloader.start();
mThumbnailDownloader.getLooper();
Log.i(TAG, "background thread started!");
}
#Override
public View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState){
View v = inflater.inflate(R.layout.fragment_photo_gallery, container, false);
mRecyclerView = (RecyclerView) v.findViewById(R.id.photo_recycler_view);
mRecyclerView.setLayoutManager(new GridLayoutManager(getActivity(), 3));
setupAdapter();
return v;
}
public void onDestroyView(){
super.onDestroyView();
mThumbnailDownloader.clearQueue();
}
#Override
public void onDestroy(){
super.onDestroy();
mThumbnailDownloader.quit();
Log.i(TAG, "background thread destroyed!");
}
private void setupAdapter(){
if (isAdded()){
mRecyclerView.setAdapter(new PhotoAdapter(mItems));
}
}
private class PhotoHolder extends RecyclerView.ViewHolder{
private ImageView mItemImageView;
public PhotoHolder(View itemView){
super(itemView);
mItemImageView = (ImageView) itemView.findViewById(R.id.item_image_view);
}
public void bindDrawable(Drawable drawable){
mItemImageView.setImageDrawable(drawable);
}
}//end PhotoHolder inner class
private class PhotoAdapter extends RecyclerView.Adapter<PhotoHolder>{
private List<GalleryItem> mGalleryItems;
public PhotoAdapter(List<GalleryItem> items){
mGalleryItems = items;
}
#Override
public PhotoHolder onCreateViewHolder(ViewGroup viewGroup, int viewType) {
LayoutInflater layoutInflater = LayoutInflater.from(getActivity());
View view = layoutInflater.inflate(R.layout.list_item_gallery, viewGroup, false);
return new PhotoHolder(view);
}
#Override
public void onBindViewHolder(PhotoHolder photoHolder, int position) {
GalleryItem galleryItem = mGalleryItems.get(position);
Drawable placeholder = getResources().getDrawable(R.drawable.wait); <--this is the placeholder image
photoHolder.bindDrawable(placeholder);//this <--this sets the placeholder but seems to wait for the thumbnail download to complete for some reason
mThumbnailDownloader.queueThumbnail(photoHolder, galleryItem.getUrl());
}
#Override
public int getItemCount() {
return mGalleryItems.size();
}
}
private class FetchItemsTask extends AsyncTask<Void, Void, List<GalleryItem>>{
#Override
protected List<GalleryItem> doInBackground(Void... params) {
return new FlickrFetchr().fetchItems();
}
#Override
protected void onPostExecute(List<GalleryItem> items){
mItems = items;
setupAdapter();
}
}//end FetchItemsTask inner class
}//end class
and here is my HandlerThread implementation:
public class ThumbnailDownloader<T> extends HandlerThread {
private static final String TAG = "ThumbnailDownloader";
private static final int MESSAGE_DOWNLOAD = 0;
private boolean mHasQuit = false;
private Handler mRequestHandler = new Handler();
private Handler mResponseHandler = new Handler();
private ThumbnailDownloadListener<T> mThumbnailDownloadListener;
private ConcurrentMap<T, String> mRequestMap = new ConcurrentHashMap<>();
public interface ThumbnailDownloadListener<T>{
void onThumbnailDownloaded(T target, Bitmap bitmap);
}
public void setThumbnailDownloadListener(ThumbnailDownloadListener<T> listener){
mThumbnailDownloadListener = listener;
}
public ThumbnailDownloader(Handler responseHandler){
super(TAG);
mResponseHandler = responseHandler;
Log.i(TAG, "ThumbnailDownloader created!");
}
#Override
protected void onLooperPrepared(){
mRequestHandler = new Handler(){
#Override
public void handleMessage(Message msg){
if (msg.what == MESSAGE_DOWNLOAD){
T target = (T) msg.obj;
Log.i(TAG, "got a request for a url:" + mRequestMap.get(target));
handleRequest(target);
}
}
};
}
#Override
public boolean quit(){
mHasQuit = true;
return super.quit();
}
public void queueThumbnail(T target, String url){
Log.i(TAG, "got a url: " + url);
if(url == null){
mRequestMap.remove(target);
}else {
mRequestMap.put(target, url);
mRequestHandler.obtainMessage(MESSAGE_DOWNLOAD, target).sendToTarget();
}
}
public void clearQueue(){
mRequestHandler.removeMessages(MESSAGE_DOWNLOAD);
mRequestMap.clear();
}
private void handleRequest(final T target){
try{
final String url = mRequestMap.get(target);
if (url == null){
return;
}
byte[] bitmapBytes = new FlickrFetchr().getUrlBytes(url);
final Bitmap bitmap = BitmapFactory.decodeByteArray(bitmapBytes, 0, bitmapBytes.length);
Log.i(TAG, "Bitmap created!"); //<---this is output in the logcat at the terminal but not the android monitor
mResponseHandler.post(new Runnable(){
#Override
public void run() {
if (mRequestMap.get(target) != null || mHasQuit){
return;
}
mRequestMap.remove(target);
mThumbnailDownloadListener.onThumbnailDownloaded(target, bitmap);
}
});
}catch (IOException ioe){
Log.e(TAG, "error downloading image: ", ioe);
}
}
}
honestly at this point i am not even sure where the problem is. it doesn't seem like queueThumbnail ever runs. but just setting the placeholder wait.png takes so long that it almost seems like there is some mix up between the placeholder and the downloaded image when it comes to binding to the ViewHolder. i am just not sure where it could be. i added comments to point this out.

Splash Screen using AsyncTask

I have a splash screen using AsyncTask, it will download some data from database and store the data in ArrayList. This ArrayList will be used for RecyclerView in fragments of MainActivity.class.
The problem is when I run the app from Android Studio to my phone, everything works perfectly. But, when I destroy the app and run it manually from my phone it will display blank white screen and then it will crash. And if I run once again after it crashed, the app will work. So, this app will always work only if I run it from Android Studio or after it crashed.
The error says that it is caused by the empty list. If I'm not mistaken, I think the AsyncTask doesn't seem to work properly after the activity is destroyed. But I don't know how to fix it. Please help me to solve this problem.
SplashScreen.java
public class SplashScreenActivity extends AppCompatActivity {
public static Event event;
private static List<Feed> feedList;
private static List<Event> eventList;
private static List<Event> todayList;
private static List<Event> upcomingList;
private static List<Partner> partnerList;
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_splashscreen);
Time today = new Time(Time.getCurrentTimezone());
today.setToNow();
Config.TODAY_DATE = String.valueOf(today.monthDay) + "-" + String.valueOf(today.month) + "-" + String.valueOf(today.year);
new DownloadData().execute("");
}
class DownloadData extends AsyncTask<String, Integer, String>
{
#Override
protected void onPreExecute() {
super.onPreExecute();
}
#Override
protected void onPostExecute(String s) {
super.onPostExecute(s);
startActivity(new Intent(getBaseContext(), WelcomeActivity.class));
finish();
}
#Override
protected String doInBackground(String... params) {
RequestHandler rh = new RequestHandler();
String JSON_STRING = rh.sendGetRequest(Config.URL_GET_ALL_DATA);
JSONObject jsonObject;
eventList = new ArrayList<>();
todayList = new ArrayList<>();
upcomingList = new ArrayList<>();
partnerList = new ArrayList<>();
feedList = new ArrayList<>();
try {
jsonObject = new JSONObject(JSON_STRING);
JSONArray getEvent = jsonObject.getJSONArray(Config.TAG_JSON_EVENT);
for (int i = 0; i < getEvent.length(); i++) {
int id = getEvent.getJSONObject(i).getInt(Config.TAG_ID);
int eoId = getEvent.getJSONObject(i).getInt(Config.TAG_EO_ID);
String eoName = getEvent.getJSONObject(i).getString(Config.TAG_EO_NAME);
String title = getEvent.getJSONObject(i).getString(Config.TAG_TITLE);
String day = getEvent.getJSONObject(i).getString(Config.TAG_DAY);
String date = getEvent.getJSONObject(i).getString(Config.TAG_DATE);
int price = getEvent.getJSONObject(i).getInt(Config.TAG_PRICE);
event = new Event(id, eoId, eoName, title, day, date, price);
eventList.add(event);
if(Config.TODAY_DATE.equals(event.getDate())){
todayList.add(event);
} else {
upcomingList.add(event);
}
}
JSONArray getPartner = jsonObject.getJSONArray(Config.TAG_JSON_PARTNER);
for (int i = 0; i < getPartner.length(); i++) {
int pId = getPartner.getJSONObject(i).getInt(Config.TAG_ID);
String pName = getPartner.getJSONObject(i).getString(Config.TAG_NAME);
String pEmail = getPartner.getJSONObject(i).getString(Config.TAG_EMAIL);
String pPhone = getPartner.getJSONObject(i).getString(Config.TAG_PHONE);
String pPhoto = getPartner.getJSONObject(i).getString(Config.TAG_PHOTO_URL);
Partner partner = new Partner(pId, pName, pEmail, pPhone, pPhoto);
partnerList.add(partner);
}
JSONArray getArticle = jsonObject.getJSONArray(Config.TAG_JSON_ARTICLE);
for (int i = 0; i < getArticle.length(); i++) {
int feedId = getArticle.getJSONObject(i).getInt(Config.TAG_ID);
String feedAuthor = getArticle.getJSONObject(i).getString(Config.TAG_FEED_AUTHOR);
String feedTitle = getArticle.getJSONObject(i).getString(Config.TAG_FEED_TITLE);
String feedContent = getArticle.getJSONObject(i).getString(Config.TAG_FEED_CONTENT);
String feedDate = getArticle.getJSONObject(i).getString(Config.TAG_FEED_DATE);
String feedThumbnail = getArticle.getJSONObject(i).getString(Config.TAG_FEED_THUMBNAIL);
Feed feed = new Feed(feedId, feedAuthor, feedTitle, feedContent, feedDate, feedThumbnail);
feedList.add(feed);
}
} catch (JSONException e) {
e.printStackTrace();
}
return JSON_STRING;
}
}
public static List<Feed> getFeedList(){ return feedList;}
public static List<Event> getEventList() {return eventList;}
public static List<Event> getTodayList() { return todayList;}
public static List<Event> getUpcomingList() { return upcomingList;}
public static List<Partner> getPartnerList() {return partnerList;}
}
DiscoverFragment.java
public class DiscoverFragment extends Fragment implements ViewPager.OnPageChangeListener, View.OnClickListener {
protected View view;
private LinearLayout pager_indicator;
private int dotsCount;
private ImageView[] dots;
private List<Feed> feedList;
private List<Event> eventList;
private List<Partner> partnerList;
public DiscoverFragment() {}
#Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setHasOptionsMenu(true);
}
#Override
public View onCreateView(LayoutInflater inflater, ViewGroup container,
Bundle savedInstanceState) {
View view = inflater.inflate(R.layout.fragment_discover, container, false);
RecyclerView recyclerViewEvent = (RecyclerView) view.findViewById(R.id.discover_event_recycler_view);
RecyclerView recyclerViewPartner = (RecyclerView) view.findViewById(R.id.discover_partner_recycler_view);
ClickableViewPager intro_images = (ClickableViewPager) view.findViewById(R.id.pager_introduction);
pager_indicator = (LinearLayout) view.findViewById(R.id.viewPagerCountDots);
eventList = SplashScreenActivity.getEventList();
partnerList = SplashScreenActivity.getPartnerList();
feedList = SplashScreenActivity.getFeedList();
EventAdapter eventAdapter = new EventAdapter(getContext(), eventList);
DiscoverPartnerAdapter discoverPartnerAdapter = new DiscoverPartnerAdapter(getContext(), partnerList);
DiscoverFeedAdapter mAdapter = new DiscoverFeedAdapter(getContext(), feedList);
final LinearLayoutManager layoutManagerEvent = new LinearLayoutManager(getContext());
final LinearLayoutManager layoutManagerPartner = new LinearLayoutManager(getContext());
layoutManagerEvent.setOrientation(LinearLayoutManager.HORIZONTAL);
layoutManagerPartner.setOrientation(LinearLayoutManager.HORIZONTAL);
addBottomDots(0);
intro_images.setAdapter(mAdapter);
intro_images.setCurrentItem(0);
intro_images.addOnPageChangeListener(this);
intro_images.setOnItemClickListener(new ClickableViewPager.OnItemClickListener() {
#Override
public void onItemClick(int position) {
Config.FEED_ID = position;
startActivity(new Intent(getContext(), ArticleActivity.class));
}
});
return view;
}
private void addBottomDots(int currentPage) {
dots = new ImageView[feedList.size()]; //the problem
pager_indicator.removeAllViews();
for (int i = 0; i < dots.length; i++) {
dots[i] = new ImageView(getContext());
dots[i].setImageDrawable(getResources().getDrawable(R.drawable.nonselecteditem_dot));
LinearLayout.LayoutParams params = new LinearLayout.LayoutParams(
LinearLayout.LayoutParams.WRAP_CONTENT,
LinearLayout.LayoutParams.WRAP_CONTENT
);
params.setMargins(4, 0, 4, 0);
pager_indicator.addView(dots[i], params);
}
if (dots.length > 0)
dots[currentPage].setImageDrawable(getResources().getDrawable(R.drawable.selecteditem_dot));
}
#Override
public void onClick(View v) {
switch (v.getId()) {
}
}
#Override
public void onPageScrolled(int position, float positionOffset, int positionOffsetPixels) {
}
#Override
public void onPageSelected(int position) {
addBottomDots(position);
for (int i = 0; i < dotsCount; i++) {
dots[i].setImageDrawable(getResources().getDrawable(R.drawable.nonselecteditem_dot));
}
dots[position].setImageDrawable(getResources().getDrawable(R.drawable.selecteditem_dot));
}
}
LogCat
01-29 00:40:57.565 32535-32535/com.irmaelita.esodiaapp E/AndroidRuntime: FATAL EXCEPTION: main
Process: com.irmaelita.esodiaapp, PID: 32535
java.lang.NullPointerException: Attempt to invoke interface method 'int java.util.List.size()' on a null object reference
at com.irmaelita.esodiaapp.fragment.DiscoverFragment.addBottomDots(DiscoverFragment.java:181)
at com.irmaelita.esodiaapp.fragment.DiscoverFragment.onCreateView(DiscoverFragment.java:158)

feedList is null. You create feedList instance when DownloadData task is executed. But you call feedList.size() in addBottomDots when fragment view should be created. So, most probably addBottomDots is called before DownloadData task is executed. You need to fix it.

The feedlist in your discover fragment is going empty while initializing. Please set a null check before doing so.It not about running from android studio.If I have understood it correctly you are trying to access a list from splasScreen activity after finishing it. ie in post execute you finish the current activity and the fragment is in main activity,so the list is going null.So if this is the case (and please correct me if not) then either download the data somewhere centrally or best way send it to main activity with intent and use it there. Also when running from android studio kill the app manually and run it again,while the phone is connected and see if it crashes in current scenario.

Send your data from doInBackground to MainActivity with sendBroadcast
Add broadcast method in DownloadData class
private void broadcast(SplashParcel parcel) {
Intent i = new Intent("splash_parcel");
i.putExtra("values", parcel);
sendBroadcast(i);
}
#Override
protected String doInBackground(String... params) {
// your code
// ..
try {
// your code
// ..
// send splashParcel to MainActivity
SplashParcel splashParcel = new SplashParcel(feedList, eventList, todayList, upcomingList, partnerList);
broadcast (splashParcel);
} catch (JSONException e) {
e.printStackTrace();
}
return JSON_STRING;
}
Add new class SplashParcel.java
public class SplashParcel implements Parcelable {
public static final Creator<SplashParcel> CREATOR = new Creator<SplashParcel>() {
#Override
public SplashParcel createFromParcel(Parcel in) {
return new SplashParcel(in);
}
#Override
public SplashParcel[] newArray(int size) {
return new SplashParcel[size];
}
};
private static List<Feed> _feedList;
private static List<Event> _eventList;
private static List<Event> _todayList;
private static List<Event> _upcomingList;
private static List<Partner> _partnerList;
protected SplashParcel(Parcel in) {
_feedList = new ArrayList<Feed>();
in.readList(_feedList, null);
_eventList = new ArrayList<Event>();
in.readList(_eventList, null);
_todayList = new ArrayList<Event>();
in.readList(_todayList, null);
_upcomingList = new ArrayList<Event>();
in.readList(_upcomingList, null);
_partnerList = new ArrayList<Partner>();
in.readList(_partnerList, null);
}
public SplashParcel(List<Feed> feedList, List<Event> eventList, List<Event> todayList, List<Event> upcomingList, List<Partner> partnerList) {
_feedList = feedList;
_eventList = eventList;
_todayList = todayList;
_upcomingList = upcomingList;
_partnerList = partnerList;
}
public SplashParcel() {
}
public List<Feed> getFeedList() {
return _feedList;
}
public void setFeedList(List<Feed> feedList) {
_feedList = feedList;
}
public List<Event> getEventList() {
return _eventList;
}
public void setEventList(List<Event> eventList) {
_eventList = eventList;
}
public List<Event> getTodayList() {
return _todayList;
}
public void setTodayList(List<Event> todayList) {
_todayList = todayList;
}
public List<Event> getUpcomingList() {
return _upcomingList;
}
public void setUpcomingList(List<Event> upcomingList) {
_upcomingList = upcomingList;
}
public List<Partner> getPartnerList() {
return _partnerList;
}
public void setPartnerList(List<Partner> partnerList) {
_partnerList = partnerList;
}
#Override
public int describeContents() {
return 0;
}
#Override
public void writeToParcel(Parcel parcel, int i) {
parcel.writeList(_feedList);
parcel.writeList(_eventList);
parcel.writeList(_todayList);
parcel.writeList(_upcomingList);
parcel.writeList(_partnerList);
}
}
MainActivity.java
// member variable
private BroadcastReceiver _splashReceiver;
private Bundle _bundle = new Bundle();
#Override
protected void onResume() {
super.onResume();
splashReceiver();
}
// receive splashParcel from SplashScreenActivity
private void splashReceiver() {
if (_splashReceiver == null) {
_splashReceiver = new BroadcastReceiver() {
#Override
public void onReceive(Context context, Intent intent) {
SplashParcel splashParcel = intent.getParcelableExtra("values");
if (splashParcel != null) {
// save splashParcel into _budle
_bundle.putParcelable("splash_parcel", splashParcel);
}
}
};
registerReceiver(_splashReceiver, new IntentFilter("splash_parcel"));
}
}
//Send _bundle to DiscoverFragment
private void showDiscoverFragment(){
if(_bundle != null) {
// create instance of discoverFragment with passing _bundle as arguments
DiscoverFragment discoverFragment = new DiscoverFragment();
discoverFragment.setArguments(_bundle);
// replace activity_main.xml with discoverFragment
getSupportFragmentManager().beginTransaction().replace(R.id.main_container, discoverFragment).addBackStack(null).commit();
}
}
In onCreateView of DiscoverFragment:
#Override
public View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState) {
SplashParcel splashParcel = getArguments().getParcelable("splash_parcel");
if(splashParcel != null) {
// your splashParcel ready in here
List<Feed> feedList = splashParcel.getFeedList()
List<Event> eventList = splashParcel.getEventList()
List<Event> todayList = splashParcel.getTodayList();
List<Event> upcommingList = splashParcel.getUpcomingList();
List<Partner> partnerList = splashParcel.getPartnerList();
}
}

List size is zero even after adding items

I have a list that I sending to a background asynctask object to do somework on. I am also sending a custom list adapter to be able to populate my list in the background. But the list returns zero and it seems like nothing is added to it as its size remains zero. I know because i debuged it. my custom list adapter works just fine though and creates the list perfectly.
Here's my code.
Fragment_Events.java
public class Fragment_Events extends android.support.v4.app.Fragment implements AdapterView.OnItemClickListener {
FragmentController controller;
ListView eventsListView;
List<Event> events;
EventsListAdapter eventsListAdapter;
public Fragment_Events() {
// Required empty public constructor
}
#Override
public void onAttach(Activity activity) {
super.onAttach(activity);
controller = (FragmentController) getActivity();
}
#Override
public void onActivityCreated(#Nullable Bundle savedInstanceState) {
super.onActivityCreated(savedInstanceState);
eventsListView = (ListView)getActivity().findViewById(R.id.listView_events);
events = new ArrayList<Event>();//SIZE REMAINS 0 <<<<<<<<<<<<<<<<<<<<<<<<<<<<<
eventsListAdapter = new EventsListAdapter(getActivity(),R.layout.list_events,events);
eventsListView.setAdapter(eventsListAdapter);
DLEvents.init(events,eventsListAdapter);
Bundle sendingBundle = new Bundle();
ArrayList<String> eventNames = new ArrayList<String>();
sendingBundle.putStringArrayList(AppUtils.EVENT_NAMES,eventNames);
controller.sendData(sendingBundle);
}
#Override
public View onCreateView(LayoutInflater inflater, ViewGroup container,
Bundle savedInstanceState) {
// Inflate the layout for this fragment
return inflater.inflate(R.layout.fragment_events, container, false);
}
#Override
public void onItemClick(AdapterView<?> parent, View view, int position, long id) {
}
}
DLEvents.java
public class DLEvents {
public static final String EVENTS_OBJECT = "Events";
public static final String NAME_COLUMN = "name";
public static final String DESC_COLUMN = "description";
public static final String DATE_COLUMN = "date";
public static final String FOLL_COLUMN = "followers";
public static final String TC_COLUMN = "ticketCount";
public static final String IMAGE_COLUMN = "image";
public static void init(List<Event> list,EventsListAdapter eventsListAdapter){
DownLoadData downLoadData = new DownLoadData(list,eventsListAdapter);
downLoadData.execute();
}
public static class DownLoadData extends AsyncTask<Void,Event,Void>{
public List<Event>events;
public EventsListAdapter eventsListAdapter;
public DownLoadData(List<Event>events, EventsListAdapter eventsListAdapter) {
super();
this.events = events;
this.eventsListAdapter = eventsListAdapter;
}
public Bitmap byteArrayToBitmap(byte[] bytes){
Bitmap temp = BitmapFactory.decodeByteArray(bytes, 0, bytes.length);
return temp;
}
#Override
protected Void doInBackground(Void... params) {
ParseQuery<ParseObject> query = ParseQuery.getQuery(EVENTS_OBJECT);
try {
for(ParseObject tempParseObject: query.find()){
String tempName = tempParseObject.getString(NAME_COLUMN);
String tempDesc = tempParseObject.getString(DESC_COLUMN);
String tempID = tempParseObject.getObjectId();
int tempTC = tempParseObject.getInt(TC_COLUMN);
ParseFile tempPF = (ParseFile)tempParseObject.get(IMAGE_COLUMN);
Bitmap tempBM = byteArrayToBitmap(tempPF.getData());
int tempFoll = tempParseObject.getInt(FOLL_COLUMN);
Event event = new Event(tempName,tempDesc,null,tempID,tempTC,tempBM,tempFoll);
publishProgress(event);
}
} catch (ParseException e) {
e.printStackTrace();
}
return null;
}
#Override
protected void onProgressUpdate(Event... values) {
super.onProgressUpdate(values);
//events.add(values[0]); //I commented it out because it causes my listview to have duplicates, if you can shed some light on this too , I'd appreciate it. Commenting it back in also doesn't affect the size of my list
eventsListAdapter.add(values[0]);
}
}
}
Asynctask seems to be working fine as the list is populated with no issues. but the list is still at a size 0 event though it's updated in the UI thread via onprogressreport
the adapter populates the list perfectly! that isn't the issue. The event's list that is being passed on to asynctask remains at a zero size. No item is being added. That is the issue.

You have to call notifyDataSetChanged() to update the adapter and let it know there is new data.
#Override
protected void onProgressUpdate(Event... values) {
super.onProgressUpdate(values);
//events.add(values[0]); //I commented it out because it causes my listview to have duplicates, if you can shed some light on this too , I'd appreciate it. Commenting it back in also doesn't affect the size of my list
eventsListAdapter.add(values[0]);
eventsListAdapter.notifyDataSetChanged();
}

You need to ask adapter to refresh itself once data is available or its data is modified.
Do this
#Override
protected void onProgressUpdate(Event... values) {
super.onProgressUpdate(values);
events.add(values[0]);
eventsListAdapter.add(values[0]);
eventsListAdapter.notifyDataSetChanged();
}