Develop Reference

Viewpager operations triggered on wrong reference

I am having a Viewpager where i am loading data of different categories. I want to show a custom dialog popup whenever user stays on a particular category for 5 seconds or more asking the user if he/she wants to share the content. For that i have used a custom dialog and am hiding/showing based on the condition.
But the problem is, that if i want to open the dialog if the user stays on Viewpager item at position let's say 3, the dialog is opening for the Viewpager item at position 4.
I am not sure why it's referencing the wrong Viewpager item.
I am including the code of Adapter class for the reference.
ArticleAdapter.java
public class ArticleAdapter extends PagerAdapter {
public List<Articles> articlesListChild;
private LayoutInflater inflater;
Context context;
View rootView;
View customArticleShareDialog, customImageShareDialog;
public int counter = 0;
int contentType = 0;
int userId;
public ArticleAdapter(Context context, List<Articles> articlesListChild, int userId) {
super();
this.context = context;
this.userId = userId;
this.articlesListChild = articlesListChild;
}
#Override
public int getCount() {
return articlesListChild.size();
}
#Override
public void destroyItem(View collection, int position, Object view) {
((ViewPager) collection).removeView((View) view);
}
private Timer timer;
private TimerTask timerTask;
public void startTimer() {
timer = new Timer();
initializeTimerTask();
timer.schedule(timerTask, 5*1000, 5*1000);
}
private void initializeTimerTask() {
timerTask = new TimerTask() {
public void run() {
switch (contentType) {
case 1:
showShareDialog("articles");
break;
case 2:
showShareDialog("images");
break;
default :
// Do Nothing
}
}
};
}
#Override
public boolean isViewFromObject(View view, Object object) {
return view == object;
}
#SuppressLint("ClickableViewAccessibility")
#Override
public Object instantiateItem(ViewGroup container, final int position) {
inflater = LayoutInflater.from(container.getContext());
View viewLayout = inflater.inflate(R.layout.article_single_item, null, false);
final ImageView contentIv, imageContentIv;
final TextView sharingTextTv;
final LinearLayout articleShareBtn, articlesLayout, imagesLayout, customArticleShareDialog, customImageShareDialog;
contentIv = viewLayout.findViewById(R.id.content_iv);
articleShareBtn = viewLayout.findViewById(R.id.article_share_btn);
articlesLayout = viewLayout.findViewById(R.id.articles_layout);
imagesLayout = viewLayout.findViewById(R.id.images_layout);
imageContentIv = viewLayout.findViewById(R.id.image_content_iv);
sharingTextTv = viewLayout.findViewById(R.id.sharing_text_tv);
customArticleShareDialog = viewLayout.findViewById(R.id.articles_share_popup);
customImageShareDialog = viewLayout.findViewById(R.id.images_share_popup);
rootView = viewLayout.findViewById(R.id.post_main_cv);
viewLayout.setTag(rootView);
articleShareBtn.setTag(rootView);
// Images
if (articlesListChild.get(position).getArticleCatId() == 1) {
articlesLayout.setVisibility(GONE);
imagesLayout.setVisibility(View.VISIBLE);
RequestOptions requestOptions = new RequestOptions();
requestOptions.placeholder(R.drawable.placeholder);
Glide.with(context)
.setDefaultRequestOptions(requestOptions)
.load(articlesListChild.get(position).getArticleImage())
.into(imageContentIv);
imageContentIv.setScaleType(ImageView.ScaleType.FIT_XY);
sharingTextTv.setText("Found this image interesting? Share it with your friends.");
counter = 0;
startTimer();
// Articles
} else if (articlesListChild.get(position).getArticleCatId() == 2){
RequestOptions requestOptions = new RequestOptions();
requestOptions.placeholder(R.drawable.placeholder);
articlesLayout.setVisibility(View.VISIBLE);
Glide.with(context)
.setDefaultRequestOptions(requestOptions)
.load(articlesListChild.get(position).getArticleImage())
.into(contentIv);
contentIv.setScaleType(ImageView.ScaleType.FIT_XY);
sharingTextTv.setText("Found this article interesting? Share it with your friends.");
counter = 0;
startTimer();
}
container.addView(viewLayout, 0);
return viewLayout;
}
public void showShareDialog(String categoryType) {
if (categoryType.equalsIgnoreCase("articles")) {
new Handler(Looper.getMainLooper()).post(new Runnable() {
public void run() {
customArticleShareDialog.setVisibility(View.VISIBLE);
}
});
} else if (categoryType.equalsIgnoreCase("images")) {
new Handler(Looper.getMainLooper()).post(new Runnable() {
public void run() {
customImageShareDialog.setVisibility(View.VISIBLE);
}
});
}
}
}
ArticleActivity.java
public class ArticleActivity extends AppCompatActivity {
#BindView(R.id.toolbar)
Toolbar toolbar;
#BindView(R.id.drawer_layout)
DrawerLayout drawer;
#BindView(R.id.articles_view_pager)
ViewPager articlesViewPager;
#BindView(R.id.constraint_head_layout)
CoordinatorLayout constraintHeadLayout;
private ArticleAdapter articleAdapter;
private List<List<Articles>> articlesList = null;
private List<Articles> articlesListChild = new ArrayList<>();
private List<Articles> articlesListChildNew = new ArrayList<>();
SessionManager session;
Utils utils;
final static int MY_PERMISSIONS_WRITE_EXTERNAL_STORAGE = 1;
int userIdLoggedIn;
LsArticlesSharedPreference lsArticlesSharedPreference;
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_home);
ButterKnife.bind(this);
toolbar.setTitle("");
toolbar.bringToFront();
session = new SessionManager(getApplicationContext());
if (session.isLoggedIn()) {
HashMap<String, String> user = session.getUserDetails();
String userId = user.get(SessionManager.KEY_ID);
userIdLoggedIn = Integer.valueOf(userId);
} else {
userIdLoggedIn = 1000;
}
utils = new Utils(getApplicationContext());
String storedTime = PreferenceManager.getDefaultSharedPreferences(getApplicationContext()).getString("lastUsedDate", "");
System.out.println("lastUsedDate : " + storedTime);
if (utils.isNetworkAvailable()) {
insertData();
ActionBarDrawerToggle toggle = new ActionBarDrawerToggle(
this, drawer, toolbar, R.string.navigation_drawer_open, R.string.navigation_drawer_close);
toggle.getDrawerArrowDrawable().setColor(getResources().getColor(R.color.colorWhite));
drawer.addDrawerListener(toggle);
if (ContextCompat.checkSelfPermission(getApplicationContext(), Manifest.permission.WRITE_EXTERNAL_STORAGE) != PackageManager.PERMISSION_GRANTED) {
ActivityCompat.requestPermissions(this,
new String[]{Manifest.permission.WRITE_EXTERNAL_STORAGE},
MY_PERMISSIONS_WRITE_EXTERNAL_STORAGE);
}
articleAdapter = new ArticleAdapter(getApplicationContext(), articlesListChild, userIdLoggedIn);
toggle.syncState();
clickListeners();
toolbar.setVisibility(View.GONE);
} else {
Intent noInternetIntent = new Intent(getApplicationContext(), NoInternetActivity.class);
startActivity(noInternetIntent);
}
}
#Override
public void onBackPressed() {
if (drawer.isDrawerOpen(GravityCompat.START)) {
drawer.closeDrawer(GravityCompat.START);
} else {
finishAffinity();
super.onBackPressed();
}
}
#Override
public void onStart() {
super.onStart();
}
#Override
public void onStop() {
super.onStop();
}
#Override
public boolean onCreateOptionsMenu(Menu menu) {
getMenuInflater().inflate(R.menu.home, menu);
return true;
}
#Override
public boolean onSupportNavigateUp() {
finish();
return true;
}
#Override
public boolean onOptionsItemSelected(MenuItem item) {
switch (item.getItemId()) {
case R.id.action_refresh:
articleAdapter.notifyDataSetChanged();
insertData();
Toast.makeText(this, "Refreshed", Toast.LENGTH_SHORT).show();
return true;
default:
return super.onOptionsItemSelected(item);
}
}
#SuppressLint("ClickableViewAccessibility")
public void clickListeners() {
}
private void insertData() {
Intent intent = new Intent(getBaseContext(), OverlayService.class);
startService(intent);
final SweetAlertDialog pDialog = new SweetAlertDialog(ArticleActivity.this, SweetAlertDialog.PROGRESS_TYPE);
pDialog.getProgressHelper().setBarColor(getResources().getColor(R.color.colorPrimary));
pDialog.setTitleText("Loading");
pDialog.setCancelable(false);
pDialog.show();
Api.getClient().getHomeScreenContents(userIdLoggedIn, new Callback<ArticlesResponse>() {
#Override
public void success(ArticlesResponse articlesResponse, Response response) {
articlesList = articlesResponse.getHomeScreenData();
if (!articlesList.isEmpty()) {
for (int i = 0; i < articlesList.size(); i++) {
articlesListChildNew = articlesList.get(i);
articlesListChild.addAll(articlesListChildNew);
}
articleAdapter = new ArticleAdapter(getApplicationContext(), articlesList, articlesListChild, userIdLoggedIn, toolbar);
articlesViewPager.setAdapter(articleAdapter);
articleAdapter.notifyDataSetChanged();
pDialog.dismiss();
} else {
List<Articles> savedArticles = lsArticlesSharedPreference.getFavorites(getApplicationContext());
if (!savedArticles.isEmpty()) {
articleAdapter = new ArticleAdapter(getApplicationContext(), articlesList, savedArticles, userIdLoggedIn, toolbar);
articlesViewPager.setAdapter(articleAdapter);
articleAdapter.notifyDataSetChanged();
pDialog.dismiss();
} else {
Api.getClient().getAllArticles(new Callback<AllArticlesResponse>() {
#Override
public void success(AllArticlesResponse allArticlesResponse, Response response) {
articlesListChild = allArticlesResponse.getArticles();
articleAdapter = new ArticleAdapter(getApplicationContext(), articlesList, articlesListChild, userIdLoggedIn, toolbar);
articlesViewPager.setAdapter(articleAdapter);
articleAdapter.notifyDataSetChanged();
};
#Override
public void failure(RetrofitError error) {
Log.e("articlesData", error.toString());
}
});
pDialog.dismiss();
}
}
}
#Override
public void failure(RetrofitError error) {
pDialog.dismiss();
Toast.makeText(ArticleActivity.this, "There was some error fetching the data.", Toast.LENGTH_SHORT).show();
}
});
}
}

Issue reason:
You face this issue because the viewpager preload fragments in background. It means that when you see 3rd fragment, the viewpager is instantiating 4th. Due to this workflow your timer for 3rd screen is cancelled and timer for 4th screen is started. Check out this link to understand what is going on.
Solution:
I would do next:
Then set page change listener for your adapter. How to do it
In this listener you can get current page and start timer for this page (and cancel timer for previously visible page).
You don't need to call startTimer() method when you instantiate item in instantiateItem() method.

Android RecyclerView does not refresh after insert

I have a problem with my RecyclerView.
I have a ProductDetailActivity which shows the detail of a product and i have a RecyclerView with its adapter in it.
The user can click on the give rating button which navigates to the RatingActivity where you can give a rating to the product.
The problem is that when i submit my rating and automatically go back to my RatingActivity, the RecyclerView does not get the recently added rating. i have to go back to my productlist and reclick on the product to see the recently added rating.
Here is my code:
ProductDetailActivity:
public class ProductDetailActivity extends AppCompatActivity {
public AppDatabase appDatabase;
private static final String DATABASE_NAME = "Database_Shop";
private RecyclerView mRecycleviewRating;
private RatingAdapter mAdapterRating;
private Button btnGoToRatingActivity;
List<Rating> ratings;
Product p;
int id;
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_product_detail);
appDatabase = Room.databaseBuilder(getApplicationContext(),AppDatabase.class,DATABASE_NAME)
.allowMainThreadQueries()
.fallbackToDestructiveMigration()
.build();
btnGoToRatingActivity = findViewById(R.id.btn_goToRatingActivity);
Intent intent = getIntent();
id = intent.getIntExtra("productid", -1);
// pour montrer tous les ratings d'un produit, tu fais un getall
p = appDatabase.productDAO().getProductById(id);
ImageView imageView = findViewById(R.id.imageDetail);
TextView textViewName = findViewById(R.id.txt_nameDetail);
TextView textViewAuthor = findViewById(R.id.txt_authorDetail);
TextView textViewCategory = findViewById(R.id.txt_categoryDetail);
TextView textViewDetail = findViewById(R.id.txt_descriptionDetail);
Picasso.get().load(p.getProductImage()).fit().centerInside().into(imageView);
textViewName.setText(p.getProductName());
textViewAuthor.setText(p.getProductAuthor());
textViewCategory.setText(p.getProductCategory());
textViewDetail.setText(p.getProductDescription());
ratings = appDatabase.ratingDAO().getRatingByProductId(id);
mRecycleviewRating = findViewById(R.id.recyclerRating_view);
LinearLayoutManager linearLayoutManager = new LinearLayoutManager(this);
linearLayoutManager.setOrientation(LinearLayoutManager.VERTICAL);
mRecycleviewRating.setLayoutManager(linearLayoutManager);
//recyclerView.setLayoutManager(new LinearLayoutManager(this));
mAdapterRating = new RatingAdapter(ratings);
mRecycleviewRating.setAdapter(mAdapterRating);
btnGoToRatingActivity.setOnClickListener(new View.OnClickListener() {
#Override
public void onClick(View v) {
Intent i = new Intent(ProductDetailActivity.this, RatingActivity.class);
i.putExtra("productid", p.getProduct_id());
startActivity(i);
}
});
mAdapterRating.notifyDataSetChanged();
}
#Override
public void onResume() {
super.onResume();
ratings = appDatabase.ratingDAO().getRatingByProductId(id); // reload the items from database
mAdapterRating.notifyDataSetChanged();
System.out.println(mAdapterRating.ratings.size());
}
}
RatingActivity:
public class RatingActivity extends AppCompatActivity implements RatingGiveFragment.RatingListener {
RelativeLayout mRelativeLayout;
private Button btnConfirmRating;
private EditText mComment;
private RatingBar mRatingBar;
public AppDatabase appDatabase;
private RatingAdapter mAdapter;
List<Rating> ratings;
private static final String DATABASE_NAME = "Database_Shop";
Product p;
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_rating);
appDatabase = Room.databaseBuilder(getApplicationContext(),AppDatabase.class,DATABASE_NAME)
.allowMainThreadQueries()
.fallbackToDestructiveMigration()
.build();
int idProduct = RatingActivity.this.getIntent().getIntExtra("productid",-1);
p = appDatabase.productDAO().getProductById(idProduct);
mRatingBar = findViewById(R.id.rating_bar);
mComment = findViewById(R.id.txt_insertOpinionText);
mRelativeLayout = findViewById(R.id.activity_rating);
btnConfirmRating = findViewById(R.id.buttonConfirmRating);
mAdapter = new RatingAdapter(ratings);
btnConfirmRating.setOnClickListener(new View.OnClickListener() {
#Override
public void onClick(View v) {
if(!checkEmptyFields()) {
Rating rating = new Rating(p.getProduct_id(),UserConnected.connectedUser.getUser_id(),mRatingBar.getRating(), UserConnected.connectedUser.getUsername(), mComment.getText().toString());
appDatabase.ratingDAO().insertRating(rating);
mAdapter.notifyDataSetChanged();
finish();
}else{
Toast.makeText(RatingActivity.this, "Empty Fields", Toast.LENGTH_SHORT).show();
}
}
});
}
/*private class insertRating extends AsyncTask<String,Integer, Integer>
{
#Override
protected Integer doInBackground(String... strings) {
Rating rating = new Rating(Integer.parseInt(strings[0]), Integer.parseInt(strings[1]), Integer.parseInt(strings[2]), strings[3], strings[4]);
appDatabase.ratingDAO().insertRating(rating);
return 1;
}
#Override
protected void onPostExecute(Integer integer) {
super.onPostExecute(integer);
if (integer == 1)
{
Toast.makeText(getApplicationContext(), getString(R.string.createRating), Toast.LENGTH_SHORT).show();
}
}
}*/
#Override
public void ratingChanged(int newRating) {
RatingTextFragment textFragment = (RatingTextFragment) getSupportFragmentManager().findFragmentById(R.id.fmt_text);
textFragment.setRating(newRating);
}
private boolean checkEmptyFields(){
if(TextUtils.isEmpty(mComment.getText().toString())){
return true;
}else{
return false;
}
}
}
RatingAdapter:
public class RatingAdapter extends RecyclerView.Adapter<RatingAdapter.RatingViewHolder> {
List<Rating> ratings;
public RatingAdapter(List<Rating> ratings){
this.ratings = ratings;
}
#NonNull
#Override
public RatingViewHolder onCreateViewHolder(#NonNull ViewGroup viewGroup, int i) {
View view = LayoutInflater.from(viewGroup.getContext()).inflate(R.layout.rating_row,viewGroup, false);
return new RatingViewHolder(view);
}
#Override
public void onBindViewHolder(#NonNull RatingViewHolder ratingViewHolder, int position) {
ratingViewHolder.ratingUsername.setText(ratings.get(position).getRatingUsername());
ratingViewHolder.ratingNumber.setText(String.valueOf(ratings.get(position).getRatingNumber()) + "/5");
ratingViewHolder.ratingComment.setText(ratings.get(position).getRatingText());
}
#Override
public int getItemCount() {
return ratings.size();
}
public static class RatingViewHolder extends RecyclerView.ViewHolder{
public TextView ratingUsername;
public TextView ratingNumber;
public TextView ratingComment;
public RatingViewHolder(#NonNull View itemView) {
super(itemView);
ratingUsername = itemView.findViewById(R.id.txt_usernamerating);
ratingNumber = itemView.findViewById(R.id.num_rating);
ratingComment = itemView.findViewById(R.id.txt_ratingComment);
}
}
}
Pictures:

You get no update in the ProductDetailActivity because you are not updating the data object ratings in the ProductDetailActivity that is the basis for the RatingAdapter.
It would be better to use startActivityForResult in the onClick()method of the ProductDetailActivity. Then you need to override the onActivityResult() method in the ProductDetailActivity. Evaluate the return values and update your data source if necessary, then call notifyDataSetChanged.
This is just pseudo code!
Changes to ProductDetailActivity:
btnGoToRatingActivity.setOnClickListener(new View.OnClickListener() {
#Override
public void onClick(View v) {
Intent i = new Intent(ProductDetailActivity.this, RatingActivity.class);
i.putExtra("productid", p.getProduct_id());
// with this you are telling the activity to expect results and..
//..to deal with them in onActivityResult
startActivityForResult(i, 1);
}
});
// You do not need this next line because setting the adaper triggers the first
//mAdapterRating.notifyDataSetChanged();
}
Add the onActivityResult() method to the ProductDetailActivity.
#Override
protected void onActivityResult(int requestCode, int resultCode, Intent data) {
if (requestCode == 1) {
if(resultCode == Activity.RESULT_OK){
// trigger a method to update the data object that is linked to the adapter
ratings = appDatabase.ratingDAO().getRatingByProductId(id);
// and now that the data has actually been updated you can call notifyDataSetChanged!!
mAdapterRating.notifyDataSetChanged();
}
if (resultCode == Activity.RESULT_CANCELED) {
//Probably do nothing or make a Toast "Canceled"??
}
}
}
Changes to RatingActivity:
btnConfirmRating.setOnClickListener(new View.OnClickListener() {
#Override
public void onClick(View v) {
if(!checkEmptyFields()) {
// I will just assume this works!
Rating rating = new Rating(p.getProduct_id(),UserConnected.connectedUser.getUser_id(),mRatingBar.getRating(), UserConnected.connectedUser.getUsername(), mComment.getText().toString());
appDatabase.ratingDAO().insertRating(rating);
Intent intent = new Intent();
//If you need to return some value.. do it here other you do not need it
//intent.putExtra("result", result);
setResult(Activity.RESULT_OK, intent);
finish();
}else{
Toast.makeText(RatingActivity.this, "Empty Fields", Toast.LENGTH_SHORT).show();
}
}
});
Please be aware in RatingActivity that in btnConfirmRating.setOnClickListener notifying the adapter with mAdapter.notifyDataSetChanged(); does nothing: firstly, because the adapter in the RatingActivity has nothing to do with the adapter in the ProductDetailActivity; secondly: you call finish(); in the next line of code.

Recycler View Adapter: Best practice to notify that data set has updated

I am trying to make a volley request to api's url. The problem is that data is fetched appropriately, but every time data set updates, the whole recycler view refreshes again and begins from the start; in the docs it is mentioned that use notifyDataSetChanged() as the last resort. How can it be avoided and what are the best practices for such tasks? Any design pattern that should be followed?
Here is the Fragment Code :-
public class PageFragment extends Fragment implements SortDialogCallback {
private static final String TAG = PageFragment.class.getSimpleName();
/**
* Unsplash API, By Default=10
*/
private static final String per_page = "10";
public static String order_By;
/**
* Unsplash API call parameter, By Default=latest
* Change it in Pager Fragment, based on Tab tapped
*/
RecyclerView recyclerView;
ImageAdapter imageAdapter;
GridLayoutManager layoutManager;
EndlessRecyclerViewScrollListener scrollListener;
FloatingActionButton actionButton;
FrameLayout no_internet_container;
Bundle savedInstanceState;
// Attaching Handler to the main thread
Handler handler = new Handler();
boolean shouldHandlerRunAgain = true;
private ArrayList<DataModel> model;
/**
* Handler is attached to the Main Thread and it's message queue, because it is the one who created it.
* <p>
* Handler is responsible for checking every second that are we connected to internet, and if we are, then :-
* 1. Then we remove empty view
* 2. Make the network call
* 3. Stop handler from posting the code again using shouldHandlerRunAgain variable
* 3.1 This is a kill switch otherwise handler will post the runnable again and again to the message queue, which will be executed as soon as it reaches the looper
* <p>
* Handler removeCallbacks is used to remove all the pending runnables in the Message Queue
*/
Runnable job = new Runnable() {
#Override
public void run() {
Log.d(TAG, "Thread run " + job.hashCode());
swapViews();
if (shouldHandlerRunAgain)
handler.postDelayed(job, HANDLER_DELAY_TIME);
}
};
#Override
public void onSaveInstanceState(Bundle outState) {
super.onSaveInstanceState(outState);
outState.putString("ORDER_BY", order_By);
}
#Override
public void onResume() {
super.onResume();
if (handler != null)
handler.post(job);
}
#Override
public void onCreate(#Nullable Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
Log.d(TAG, "Starting Handler");
layoutManager = new GridLayoutManager(getContext(), 2);
scrollListener = new EndlessRecyclerViewScrollListener(layoutManager) {
public void onLoadMore(int page, int totalItemsCount, RecyclerView view) {
Log.w(TAG, "On load More Called with page number " + page);
loadDataUsingVolley(page, order_By);
}
};
}
#Override
public boolean onOptionsItemSelected(MenuItem item) {
switch (item.getItemId()) {
case R.id.search:
Toast.makeText(getContext(), "Async task", Toast.LENGTH_SHORT).show();
break;
default:
Toast.makeText(getContext(), "Invalid Options", Toast.LENGTH_SHORT).show();
}
return true;
}
#Override
public void onCreateOptionsMenu(Menu menu, MenuInflater inflater) {
inflater.inflate(R.menu.menu_page_fragment, menu);
}
private void swapViews() {
if (detectConnection(getContext()) == false) {
recyclerView.setVisibility(View.INVISIBLE);
actionButton.setVisibility(View.INVISIBLE);
no_internet_container.setVisibility(View.VISIBLE);
} else {
Log.d(TAG, "Removing callbacks from handler and stopping it from posting");
shouldHandlerRunAgain = false;
handler.removeCallbacks(job, null);
handler = null;
recyclerView.setVisibility(View.VISIBLE);
actionButton.setVisibility(View.VISIBLE);
no_internet_container.setVisibility(View.INVISIBLE);
if (savedInstanceState != null) {
loadDataUsingVolley(1, savedInstanceState.getString("ORDER_BY"));
} else {
order_By = "latest";
loadDataUsingVolley(1, order_By);
}
}
}
#Nullable
#Override
public View onCreateView(LayoutInflater inflater, #Nullable ViewGroup container, final Bundle savedInstanceState) {
this.savedInstanceState = savedInstanceState;
View view = inflater.inflate(R.layout.fragment_page, container, false);
actionButton = (FloatingActionButton) view.findViewById(R.id.sort_button);
actionButton.setOnClickListener(new View.OnClickListener() {
#Override
public void onClick(View view) {
SortDialog sortDialog = new SortDialog();
sortDialog.setTargetFragment(PageFragment.this, 911);
sortDialog.show(getChildFragmentManager(), "sortfragment");
}
});
recyclerView = (RecyclerView) view.findViewById(R.id.recyclerview);
recyclerView.setHasFixedSize(true);
no_internet_container = (FrameLayout) view.findViewById(R.id.no_internet_container);
return view;
}
void setUpRecyclerView() {
if (imageAdapter == null)
imageAdapter = new ImageAdapter(getContext(), (model==null)?new ArrayList<DataModel>():model);
recyclerView.setAdapter(imageAdapter);
recyclerView.setLayoutManager(layoutManager);
recyclerView.addOnScrollListener(scrollListener);
}
void loadDataUsingVolley(int page, String order_by) {
final ProgressDialog dialog = ProgressDialog.show(getContext(), "Wallser", "Loading");
RequestQueue requestQueue = Volley.newRequestQueue(getContext());
String URL = "https://api.unsplash.com/photos/?page=" + page + "&client_id=" + api_key + "&per_page=" + per_page + "&order_by=" + order_by;
Log.d(TAG, URL);
JsonArrayRequest objectRequest = new JsonArrayRequest(Request.Method.GET, URL, null, new Response.Listener<JSONArray>() {
#Override
public void onResponse(JSONArray array) {
int len = array.length();
if (model == null)
model = new ArrayList<>();
for (int i = 0; i < len; i++) {
try {
JSONObject object = array.getJSONObject(i);
String id = object.getString("id");
JSONObject object1 = object.getJSONObject("urls");
String imageURL = object1.getString("regular");
JSONObject object2 = object.getJSONObject("links");
String downloadURL = object2.getString("download");
model.add(new DataModel(imageURL, downloadURL, id));
Log.d(TAG, downloadURL);
} catch (JSONException e) {
e.printStackTrace();
}
}
if (dialog != null) {
dialog.dismiss();
}
Log.d(TAG, model.size() + "");
setUpRecyclerView();
}
}, new Response.ErrorListener() {
#Override
public void onErrorResponse(VolleyError error) {
dialog.dismiss();
Toast.makeText(getContext(), "" + error.getMessage(), Toast.LENGTH_SHORT).show();
}
});
requestQueue.add(objectRequest);
}
/**
* marks a new network call to Unsplash API
* Thus, set model array list to null, to start fresh.
* as model is reset, ImageAdapter also needs to start fresh.
*
* #param order_by
*/
#Override
public void onDialogFinish(String order_by) {
model = null;
imageAdapter=null;
order_By = order_by;
loadDataUsingVolley(1, order_By);
}
}

Why is this implementation of parcelables to save and restore Custom Arraylist not Working

I am fetching data from json with Volley and populating RecyclerView with the parsed data but I ran into a bit of problem:
The call to get the items is in onCreate method, so the call is repeated each time the activity is recreated both from configuration changes and otherwise; hence the data is reloaded. So I found this answer that uses parcelables
and this article on Codepath (still on parcelables). After I have followed the instructions explicitly (or so I feel), there seems to be no change: the call to get data is repeated each time the activity is recreated.
FruitItems
public class FruitItems implements Parcelable {
private String fruit_title;
private String fruit_description;
private String fruit_image;
public String getFruit_title() {
return fruit_title;
}
public void setFruit_title(String fruit_title) {
this.fruit_title = fruit_title;
}
public String getFruit_description() {
return fruit_description;
}
public void setFruit_description(String fruit_description) {
this.fruit_description = fruit_description;
}
public String getFruit_image() {
return fruit_image;
}
public void setFruit_image(String fruit_image) {
this.fruit_image = fruit_image;
}
#Override
public int describeContents() {
return 0;
}
#Override
public void writeToParcel(Parcel dest, int flags) {
dest.writeString(this.fruit_title);
dest.writeString(this.fruit_description);
dest.writeString(this.fruit_image);
}
public FruitItems() {
}
protected FruitItems(Parcel in) {
this.fruit_title = in.readString();
this.fruit_description = in.readString();
this.fruit_image = in.readString();
}
public static final Parcelable.Creator<FruitItems> CREATOR = new Parcelable.Creator<FruitItems>() {
#Override
public FruitItems createFromParcel(Parcel source) {
return new FruitItems(source);
}
#Override
public FruitItems[] newArray(int size) {
return new FruitItems[size];
}
};
}
MainActivity
public class MainActivity extends AppCompatActivity {
private final String TAG = "MainActivity";
private final String KEY_POST_ITEMS = "fruititems";
//List of fruits
private List<FruitItems> mFruitItemsList;
//Views
private RecyclerView recyclerView;
private RecyclerView.Adapter adapter;
private ProgressDialog mProgressDialog;
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
Log.d(TAG, "onCreate called");
//Initializing Views
recyclerView = (RecyclerView) findViewById(R.id.fruit_recycler);
LinearLayoutManager layoutManager = new LinearLayoutManager(this);
recyclerView.setLayoutManager(layoutManager);
if (savedInstanceState != null && savedInstanceState.containsKey(KEY_POST_ITEMS)) {
mFruitItemsList = savedInstanceState.getParcelableArrayList(KEY_POST_ITEMS);
} else {
//Initializing the fruitlist
mFruitItemsList = new ArrayList<>();
if (NetworkCheck.isAvailableAndConnected(this)) {
getData();
} else {
final Context mContext;
mContext = this;
final AlertDialog.Builder alertDialogBuilder = new AlertDialog.Builder(this);
alertDialogBuilder.setTitle(R.string.alert_titl);
alertDialogBuilder.setCancelable(false);
alertDialogBuilder.setIcon(R.mipmap.ic_launcher);
alertDialogBuilder.setMessage(R.string.alert_mess);
alertDialogBuilder.setPositiveButton(R.string.alert_retry, new DialogInterface.OnClickListener() {
#Override
public void onClick(DialogInterface dialog, int which) {
if (!NetworkCheck.isAvailableAndConnected(mContext)) {
alertDialogBuilder.show();
} else {
getData();
}
}
});
alertDialogBuilder.setNegativeButton(R.string.alert_cancel, new DialogInterface.OnClickListener() {
#Override
public void onClick(DialogInterface dialog, int which) {
finish();
}
});
alertDialogBuilder.show();
}
}
adapter = new FruitAdapter(mFruitItemsList, this);
recyclerView.setAdapter(adapter);
}
#Override
public void onSaveInstanceState(Bundle savedInstanceState) {
savedInstanceState.putParcelableArrayList(KEY_POST_ITEMS, ArrayList<? extends Parcelable>))mFruitItemsList);
super.onSaveInstanceState(savedInstanceState);
}
//Getting json data
private void getData(){
Log.d(TAG, "getData called");
//Show progress dialog
mProgressDialog = new ProgressDialog(MainActivity.this);
mProgressDialog.setCancelable(false);
mProgressDialog.setMessage(this.getResources().getString(R.string.load_fruit));
mProgressDialog.show();
//Creating a json request
JsonArrayRequest jsonArrayRequest = new JsonArrayRequest(ConfigFruit.GET_URL,
new Response.Listener<JSONArray>() {
#Override
public void onResponse(JSONArray response) {
Log.d(TAG, "onResponse called");
//Dismissing the progress dialog
if (mProgressDialog != null) {
mProgressDialog.hide();
}
//calling method to parse json array
parseData(response);
}
},
new Response.ErrorListener() {
#Override
public void onErrorResponse(VolleyError error) {
}
});
//Creating request queue
RequestQueue requestQueue = Volley.newRequestQueue(this);
//Adding request to the queue
requestQueue.add(jsonArrayRequest);
}
//parsing json data
private void parseData(JSONArray array){
Log.d(TAG, "Parsing array");
for(int i = 0; i<array.length(); i++) {
FruitItems fruitItem = new FruitItems();
JSONObject jsonObject = null;
try {
jsonObject = array.getJSONObject(i);
fruitItem.setFruit_title(jsonObject.getString(ConfigFruit.TAG_POST_TITLE));
fruitItem.setFruit_description(jsonObject.getString(ConfigFruit.TAG_POST_DESCRIPTION));
//Parsing image
JSONObject fruitImage = jsonObject.getJSONObject("thumbnail");
fruitItem.setFruit_image(fruitImage.getString("url"));
} catch (JSONException w) {
w.printStackTrace()
}
mFruitItemsList.add(fruitItem);
}
adapter.notifyItemRangeChanged(0, adapter.getItemCount());
}
}
I may not be a pro but I know that I have goofed somewhere in the codes above, else it should have worked.
Now, my question is where did I goof and how do I plug this mistake?
EDIT
I have edited the codes above to reflect the answer that I accepted. It works fine but there is still a problem.
I start Activity B from MainActivity. If I press the back-button in Activity B the data is saved but when I press the up-button, the getData is called again and the data is re-fetched.
Please, is there anyway around this?

You don't seem to have an onSaveInstanceState in your mainactivity. You need something like
#Override
protected void onSaveInstanceState (Bundle outState) {
super.onSaveInstanceState(outState);
outState.putParcelableArrayList(KEY_POST_ITEMS,mFruitItemsList) ;
}

In order to retain your data for the activity that is about to be destructed and the one that is being created, you need to override the onSaveInstance callback
#Override
public void onSaveInstanceState(Bundle savedInstanceState) {
savedInstanceState.putParcelableArrayList(KEY_POST_ITEMS, (ArrayList)mFruitItemsList);
super.onSaveInstanceState(savedInstanceState);
}
NOTE: always remember to call the superclass.

Refreshing listview to update the data?

I've a listview with some static data. When the refresh activity is done, some data need to be updated in listview. The problem is once the refresh gets completed, the new items are not updated.
MainActivity.class
public class MainActivity extends ActionBarActivity {
SwipeRefreshLayout swipeLayout;
String[] players = {"Dravid","Ganguly","Sachin","Irfan pathan","Balaji","Bhuvi","Praveen"};
ListView listView;
ArrayAdapter<String> adapter = null;
ArrayList al = new ArrayList();
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
listView = (ListView)findViewById(R.id.listView);
for (int i =0; i<players.length; i++)
{
Bean b = new Bean();
b.setName(players[i]);
al.add(b);
}
adapter = new ArrayAdapter<String>(this,android.R.layout.simple_list_item_1,players);
listView.setAdapter(adapter);
swipeLayout = (SwipeRefreshLayout) findViewById(R.id.swipe_container);
swipeLayout.setOnRefreshListener(new SwipeRefreshLayout.OnRefreshListener() {
#Override
public void onRefresh() {
swipeLayout.setRefreshing(true);
new updateItems().execute();
}
});
swipeLayout.setColorScheme(android.R.color.holo_blue_bright,
android.R.color.holo_green_light,
android.R.color.holo_orange_light,
android.R.color.holo_red_light);
}
class updateItems extends AsyncTask<Void, Void, Void>
{
#Override
protected void onPreExecute() {
super.onPreExecute();
}
#Override
protected Void doInBackground(Void... params) {
String[] newitems = {"Ishant sharma","Ramesh power","Kaif"};
// adapter = new ArrayAdapter<String>(MainActivity.this,android.R.layout.simple_list_item_1,newitems);
for (int j=0;j<newitems.length;j++)
{
Bean bb = new Bean();
bb.setName(newitems[j]);
al.add(bb);
}
return null;
}
#Override
protected void onPostExecute(Void aVoid) {
super.onPostExecute(aVoid);
runOnUiThread(new Runnable() {
#Override
public void run() {
adapter.notifyDataSetChanged();
listView.invalidateViews();
}
});
swipeLayout.setRefreshing(false);
}
}
#Override
public boolean onCreateOptionsMenu(Menu menu) {
// Inflate the menu; this adds items to the action bar if it is present.
getMenuInflater().inflate(R.menu.menu_main, menu);
return true;
}
#Override
public boolean onOptionsItemSelected(MenuItem item) {
// Handle action bar item clicks here. The action bar will
// automatically handle clicks on the Home/Up button, so long
// as you specify a parent activity in AndroidManifest.xml.
int id = item.getItemId();
//noinspection SimplifiableIfStatement
if (id == R.id.action_settings) {
return true;
}
return super.onOptionsItemSelected(item);
}
}
Bean.class
public class Bean {
String name;
public String getName() {
return name;
}
public void setName(String name) {
this.name = name;
}
}
Where i am making mistake?

This is the adapter that you're setting initially :
adapter = new ArrayAdapter<String>(this,android.R.layout.simple_list_item_1,players);
Inside your doInBackground() method, you update the a1 ArrayList but your players Array on which the adapter depends remains the same hence no changes are reflected in the listview even when you do adapter.notifyDataSetChanged().
Secondly, the onPostExecute method runs on the ui thread so you do not need to do that explicitly.