Develop Reference

Fragment recyclerView adapter notifyDataSetChanged() from MainActivity

Please find me to solve this issue , i have a list of image url in a json api ,list url api is calling from background task and after compliting called notify method its not showing
but the Recyclerview doesn't refresh - only if I go back and reopen the activity - the new data is shown.
So how can I notify the adapter that there's new data to display?
1.WallpaperFragmentAdapter.java
public class WallpaperFragmentAdapter extends Fragment {
List<WallpaperMain> wallpaperList = new ArrayList<WallpaperMain>();
WallPaperAdapter wallPaperAdapter;
#Bind(R.id.recyclerView)
RecyclerView recyclerView;
private int tabId ;
public void settabId(int tabId){
this.tabId=tabId;
}
public static Fragment newInstance(Context context) {
WallpaperFragmentAdapter f = new WallpaperFragmentAdapter();
return f;
}
public View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState) {
ViewGroup root = (ViewGroup) inflater.inflate(R.layout.content_main, null);
setUpView(root);
return root;
}
void setUpView(ViewGroup root){
ButterKnife.bind(this, root);
setUPList();
}
void setUPList(){
new WallPaperListDownlaoderTask().execute("http://localhost:8080/api/motivation/wallpaper/wallpaper");
recyclerView.setLayoutManager(new LinearLayoutManager(getActivity()));
GridLayoutManager gridLayoutManager = new GridLayoutManager(getActivity(),3);
wallPaperAdapter = new WallPaperAdapter(wallpaperList,getActivity());
recyclerView.setAdapter(wallPaperAdapter);
recyclerView.setLayoutManager(gridLayoutManager);
System.out.println(wallPaperAdapter);
recyclerView.addOnItemTouchListener(new RecyclerTouchListener(getActivity(), recyclerView, new RecyclerTouchListener.ClickListener() {
#Override
public void onClick(View view, int position) {
Intent intent;
intent = new Intent(getActivity(), WallpaperDeatilsActivity.class);
startActivity(intent);
}
#Override
public void onLongClick(View view, int position) {
}
}));
}
class WallPaperListDownlaoderTask extends AsyncTask<String,Integer,JSONArray> {
OkHttpClient client = new OkHttpClient();
#Override
protected void onPreExecute() {
super.onPreExecute();
}
#Override
protected JSONArray doInBackground(String... params) {
String url =params[0];
Request request = new Request.Builder()
.url(url)
.build();
try{
Response response = client.newCall(request).execute();
String apiResponseString=response.body().string();
System.out.println("response.body().toString() ---- "+apiResponseString );
JSONArray jsonArray = new JSONArray(apiResponseString);
List<WallpaperMain> wallpaperMains = new ArrayList<>();
for(int index =0;index<jsonArray.length();index++){
try {
JSONObject wallpaperMainsJsonObj = jsonArray.getJSONObject(index);
WallpaperMain wallpaperMain = new WallpaperMain();
wallpaperMain.setId(wallpaperMainsJsonObj.getInt("id"));
Wallpaper wallpaper = new Wallpaper();
JSONObject wallpaperJsonObj = wallpaperMainsJsonObj.getJSONObject("wallpaper");
wallpaper.setLarge(wallpaperJsonObj.getString("large"));
wallpaperMain.setWallpaper(wallpaper);
wallpaperMains.add(wallpaperMain);
} catch (JSONException e) {
e.printStackTrace();
}
}
wallpaperList =wallpaperMains;
return null;
}catch (IOException e){
Log.v("",e.toString());
} catch (JSONException e) {
e.printStackTrace();
}
return null;
}
#Override
protected void onPostExecute(JSONArray jsonArray) {
super.onPostExecute(jsonArray);
System.out.println(wallPaperAdapter);
wallPaperAdapter.notifyDataSetChanged();
recyclerView.setAdapter(wallPaperAdapter);
System.out.println(wallpaperList.size());
}
}
}
2.WallPaperAdapter.java
public class WallPaperAdapter extends RecyclerView.Adapter<WallPaperAdapter.MyViewHolder>{
private List<WallpaperMain> wallpaperMains;
private Context context;
public WallPaperAdapter(List<WallpaperMain> wallpaperMains,Context context){
this.wallpaperMains =wallpaperMains;
this.context=context;
}
#Override
public WallPaperAdapter.MyViewHolder onCreateViewHolder(ViewGroup parent, int viewType) {
View itemLayoutView = LayoutInflater.from(parent.getContext()).inflate(R.layout.wallpaper_item, null);
WallPaperAdapter.MyViewHolder viewHolder = new WallPaperAdapter.MyViewHolder(itemLayoutView);
return viewHolder;
}
#Override
public void onBindViewHolder(MyViewHolder holder, int position) {
Glide.with(context)
.load("http://localhost:8080/api/motivation/wallpaper/large/37l")
.into(holder.waIlpapermageView);
// holder.waIlpapermageView.setImageResource(R.drawable.name);
}
#Override
public int getItemCount() {
return wallpaperMains.size();
}
public class MyViewHolder extends RecyclerView.ViewHolder {
ImageView waIlpapermageView;
public MyViewHolder(View itemView) {
super(itemView);
waIlpapermageView =(ImageView) itemView.findViewById(R.id.wallpaperItem_imageView);
}
}
}
OUTPUT I am getting bellow

In your doInBackground method , instead of
wallpaperList = wallpaperMains;
use
wallpaperList.clear();
wallpaperList.addAll(wallpaperMains);
In onPostExecute()
#Override
protected void onPostExecute(JSONArray jsonArray) {
super.onPostExecute(jsonArray);
System.out.println(wallPaperAdapter);
wallPaperAdapter.notifyDataSetChanged();
System.out.println(wallpaperList.size());
}

Try this...
Please clear your Arraylist before adding the values wallpaperList.clear(); On onPreExecute() method.
recyclerView.setAdapter(wallPaperAdapter);
wallPaperAdapter.notifyDataSetChanged();
Whenever your ArrayList value is changing usenotifyDataSetChanged(); it will refresh your Recylierview

Transferring data into a separate ArrayList and displaying in RecyclerView

I have two ArrayLists from which I am trying to insert data into separate static ArrayList in another class and display in RecyclerView, but the recycler is not getting populated though the same was being done with a dummy ArrayList.Please help me with this problem.
My Class where I am inserting data from phoneContactNos and phoneContactName in two separate ArrayList: Common.selectedContactNos and Common.selectedContactName.
public void displayMatchedContacts()
{
try {
for (int i = 1; i < phoneContactNos.size(); i++) {
if (phoneContactNos.contains(registeredContactNos.get(i))) {
if (registeredContactNos.get(i) != null) {
try {
indexOfRegNumber = phoneContactNos.indexOf(registeredContactNos.get(i));
//Common.indexPosition_contacts=indexOfRegNumber;
Toast.makeText(this, "index" + String.valueOf(indexOfRegNumber), Toast.LENGTH_LONG).show();
if ((phoneContactNos.get(indexOfRegNumber) != null) &&(phoneContactName.get(indexOfRegNumber) != null)) {
//String regName="";
//String regContact="";
Common.selectedContactNos.add(phoneContactNos.get(indexOfRegNumber));
//Toast.makeText(this,selectedContactNos.get(i).toString(),Toast.LENGTH_SHORT).show();
//Toast.makeText(this,phoneContactNos.get(indexOfRegNumber).toString(),Toast.LENGTH_SHORT).show();
Common.selectedContactName.add(phoneContactName.get(indexOfRegNumber));
//Toast.makeText(this,selectedContactName.get(i).toString(),Toast.LENGTH_SHORT).show();
//Toast.makeText(this, phoneContactName.get(indexOfRegNumber).toString(), Toast.LENGTH_SHORT).show();
} else {
Toast.makeText(this, "null index no", Toast.LENGTH_SHORT).show();
}
} catch (Exception e) {
Log.i("Contacts display error", e.getLocalizedMessage());
e.printStackTrace();
}
}
}
}
}catch (Exception e)
{
Log.i("Contacts error in loop", e.getLocalizedMessage());
e.printStackTrace();
}
}
My Common class
public final class Common {
public static ArrayList<String> selectedContactNos=new ArrayList<>();
public static ArrayList<String> selectedContactName=new ArrayList<>();
public static String fcmId="";
public static int position;
public static String contacts_list="";
public static int indexPosition_contacts;
}
My RecyclerView populating code
public void populateList() {
Log.i("Populate List","Entered");
LinearLayoutManager mLinearLayoutManager = new LinearLayoutManager(this);
recyclerView_contacts.setLayoutManager(mLinearLayoutManager);
displayRecyclerAdapter = new DisplayRecyclerAdapter(this);
recyclerView_contacts.setAdapter(displayRecyclerAdapter);
}
My Adapter Class
public class DisplayRecyclerAdapter extends RecyclerView.Adapter<DisplayRecyclerAdapter.displayViewHolder> {
private LayoutInflater mInflater;
private Context context;
Fragment fragment;
FragmentTransaction ft;
FrameLayout container;
public DisplayContacts displayContacts;
public DisplayRecyclerAdapter(Context context) {
this.mInflater = LayoutInflater.from(context);
this.context = context;
ft = ((AppCompatActivity) context).getSupportFragmentManager().beginTransaction();
//displayContacts = new DisplayContacts();
}
#Override
public displayViewHolder onCreateViewHolder(ViewGroup parent, int viewType) {
View view = mInflater.inflate(R.layout.contacts_row, parent, false);
displayViewHolder holder = new displayViewHolder(view);
return holder;
}
#Override
public void onBindViewHolder(displayViewHolder holder, int position) {
holder.setData(position);
//Common.position = position;
holder.setListeners();
//for(int i=0;i<((DisplayContacts)context).selectedContactName.size();i++)
for(int i=0;i<Common.selectedContactName.size();i++)
{
//String contactName=((DisplayContacts)context).selectedContactName.get(i);
String contactName=Common.selectedContactName.get(i);
//String contactNumber=((DisplayContacts)context).selectedContactNos.get(i);
String contactNumber=Common.selectedContactNos.get(i);
Toast.makeText(context,contactName+","+contactNumber,Toast.LENGTH_SHORT).show();
}
}
class displayViewHolder extends RecyclerView.ViewHolder implements View.OnClickListener {
int position;
//ImageView productSearchImg;
TextView name_contactList;
Button call_contact;
public displayViewHolder(View itemView) {
super(itemView);
name_contactList = (TextView) itemView.findViewById(R.id.contactlist_name);
call_contact = (Button) itemView.findViewById(R.id.contactlist_call);
}
public void setData(int position) {
this.position = position;
//String displayContacts=((DisplayContacts) context).selectedContactName.get(position);
String displayContacts=Common.selectedContactName.get(position);
Toast.makeText(context,"name to display"+ displayContacts,Toast.LENGTH_SHORT).show();
//name_contactList.setText(((DisplayContacts) context).selectedContactName.get(position));
//name_contactList.setText(displayContacts);
name_contactList.setText("dummy text");
}
#Override
public void onClick(View v) {
//sendPushNotification();
startAudioCall();
}
public void setListeners() {
call_contact.setOnClickListener(displayViewHolder.this);
}
}
public void startAudioCall() {
Intent i = new Intent(context, AudioCallActivity.class).setFlags(Intent.FLAG_ACTIVITY_NEW_TASK);
context.startActivity(i);
}
#Override
public int getItemCount() {
return ((DisplayContacts) context).selectedContactName.size();
}
}

can be one of two things:
1.you are not attaching the adapter with data,hence empty
2.or you are updating your data but not calling notifyDataSetChanged()
try to pass the list data in your Adapter class while you are creating it,then attach it to the recyelerview.
//to give a vary basic example
List dataList;
RvAdapter(Context c,List data){
this.dataList=data;
}
onBidViewHolder(Viewholder holder,int position){
holder.tvName.setText(dataList.get(position).getName());
.......
}
//in your activity/fragment
RvAdapter adapter=new RavAdapter(context,dataList);
recylerview.setAdapter(adapter);
//if you change your data
adapter.notifyDataSetChanged()

How to access a list in a hosting Activity from an external AlertDialog

I have a recyclerView with a list of Competitor objects. The list that populates the RecyclerView is a global Singleton. In that Singleton's constructor I open a Json file, parse it's contents to populate the global Singleton's list of Competitors and use that list to pass to the RecyclerView's adapter. Each list item has an ImageButton. This is what I'm trying to accomplish;
When the user clicks on the ImageButton (Delete Button) I want an AlertDialog to pop up and ask the user if they are sure they want to delete the Competitor. This part I have so far. But what I need to do next I can't figure out. I am able to update the json file that contains the global list's information but I also want to update the recyclerview by removing the Competitor from the RecyclerView by calling:
mCompetitorsList.remove(competitor); notifyItemRemoved(position);
However I can't get a reference to the mCompetitorsList variable from an external Dialog class. The same goes for calling notifiyItemRemoved(position)
What should I do? Below is the code for my Dialog class, my Activity that contains the RecyclerView and it's Adapter as well as the Singleton implementation.
public class MasterCompetitorsListActivity extends AppCompatActivity implements SearchView.OnQueryTextListener {
private static final String DIALOG_DELETE_COMPETITOR = "DIALOG_DELETE_COMPETITOR";
private RecyclerView mRecyclerView;
private List<Competitor> mCompetitorsList;
private CompetitorListAdapter mAdapter;
private SearchView mSearchView;
private FloatingActionButton mAddCompetitorButton;
private Button mDeletCompetitor;
private TextView mCompetitorHidden;
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_master_competitors_list);
mSearchView = (SearchView) findViewById(R.id.searchView);
mSearchView.setOnQueryTextListener(this);
/* initialize the Global Competitor's List for the recyclerview. Because this is a singleton
it should initialize the list for the entire app's runtime
*/
GlobalCompetitorsList.get();
mCompetitorsList = GlobalCompetitorsList.getCompetitors();
mRecyclerView = (RecyclerView) findViewById(R.id.master_competitors_recycler);
LinearLayoutManager layoutManager = new LinearLayoutManager(this);
mRecyclerView.setLayoutManager(layoutManager);
mAdapter = new CompetitorListAdapter(this, mCompetitorsList);
mRecyclerView.setAdapter(mAdapter);
// set a separator for the list items
DividerItemDecoration divider = new DividerItemDecoration(
mRecyclerView.getContext(),
layoutManager.getOrientation());
divider.setDrawable(ContextCompat.getDrawable(MasterCompetitorsListActivity.this, R.drawable.divider_dark));
mRecyclerView.addItemDecoration(divider);
mRecyclerView.setAdapter(mAdapter);
mAddCompetitorButton = (FloatingActionButton) findViewById(R.id.add_master_competitor_floating_button);
mAddCompetitorButton.setOnClickListener(new View.OnClickListener() {
#Override
public void onClick(View view) {
Intent intent = new Intent(MasterCompetitorsListActivity.this, AddNewMasterCompetitorActivity.class);
startActivity(intent);
}
});
}
#Override
public boolean onQueryTextSubmit(String query) {
mCompetitorsList = new ArrayList<>();
mCompetitorsList = GlobalCompetitorsList.getCompetitors();
mAdapter.notifyDataSetChanged();
return false;
}
#Override
public boolean onQueryTextChange(String query) {
mCompetitorsList = GlobalCompetitorsList.getCompetitors();
query = query.toLowerCase();
final List<Competitor> filteredList = new ArrayList<>();
for (int i = 0; i < mCompetitorsList.size(); i++) {
final String lastName = mCompetitorsList.get(i).getLastName().toLowerCase();
final String firstName = mCompetitorsList.get(i).getFirstName().toLowerCase();
if (lastName.contains(query) || firstName.contains(query)) {
filteredList.add(mCompetitorsList.get(i));
}
}
mAdapter.setFilter(filteredList);
return true;
}
// ********* RecyclerView Adapter class *************************************************************************
public class CompetitorListAdapter extends RecyclerView.Adapter<CompetitorListAdapter.CompetitorViewHolder> {
List<Competitor> mCompetitors;
Context mContext;
public CompetitorListAdapter(Context context, List<Competitor> competitors) {
mContext = context;
mCompetitors = competitors;
}
#Override
public CompetitorListAdapter.CompetitorViewHolder onCreateViewHolder(ViewGroup parent, int viewType) {
LayoutInflater inflater = LayoutInflater.from(MasterCompetitorsListActivity.this);
View itemView = inflater.inflate(R.layout.list_item_master_competitor, parent, false);
CompetitorViewHolder viewHolder = new CompetitorViewHolder(itemView);
return viewHolder;
}
#Override
public void onBindViewHolder(CompetitorListAdapter.CompetitorViewHolder holder, final int position) {
final Competitor competitor = mCompetitorsList.get(position);
try {
holder.firstName.setText(competitor.getFirstName());
holder.lastName.setText(competitor.getLastName());
holder.memberNum.setText(competitor.getMemberNum());
holder.deleteCompetitor.setImageResource(R.drawable.ic_delete_forever_white_24dp);
holder.container.findViewById(R.id.main_container);
holder.hiddenCompetitorId.setText(competitor.getCompetitorId().toString());
} catch (Exception e) {
e.printStackTrace();
}
holder.deleteCompetitor.setOnClickListener(new View.OnClickListener() {
#Override
public void onClick(View view) {
FragmentManager fragmentManager = getSupportFragmentManager();
DeleteCompetitorDialogFragment dialog = new DeleteCompetitorDialogFragment();
dialog.show(fragmentManager, DIALOG_DELETE_COMPETITOR);
// mCompetitorsList.remove(competitor); // remove from the global singleton list
// notifyItemRemoved(position);
}
});
}
#Override
public int getItemCount() {
return mCompetitorsList.size();
}
// ************* View Holder Class **************************************************************************
public class CompetitorViewHolder extends RecyclerView.ViewHolder {
public TextView firstName;
public TextView lastName;
public TextView memberNum;
public ImageButton deleteCompetitor;
public ConstraintLayout container;
public TextView hiddenCompetitorId;
boolean comptitorIsActive = false;
public CompetitorViewHolder(final View itemView) {
super(itemView);
firstName = (TextView) itemView.findViewById(R.id.first_name);
lastName = (TextView) itemView.findViewById(R.id.last_name);
deleteCompetitor = (ImageButton) itemView.findViewById(R.id.delete_competitor_button);
hiddenCompetitorId = (TextView) itemView.findViewById(R.id.competitor_id_hidden);
container = (ConstraintLayout) itemView.findViewById(R.id.main_container);
memberNum = (TextView) itemView.findViewById(R.id.member_num);
}
}
// ************ End of View Holder Class ********************************************************************
public void setFilter(List<Competitor> newList) {
mCompetitorsList = new ArrayList<>();
mCompetitorsList.addAll(newList);
notifyDataSetChanged();
}
}
// ************* End of RecyclerView Adapter class **********************************************************
}
Here is the Dialog class:
public class DeleteCompetitorDialogFragment extends DialogFragment {
#Override
public Dialog onCreateDialog(Bundle savedInstanceState){
final GlobalCompetitorsList mCompetitorsList = GlobalCompetitorsList.get();
return new AlertDialog.Builder(getActivity())
.setTitle("Delete this Competitor?")
.setNegativeButton(android.R.string.cancel, new DialogInterface.OnClickListener() {
#Override
public void onClick(DialogInterface dialogInterface, int i) {
}
})
.setPositiveButton(android.R.string.ok, new DialogInterface.OnClickListener() {
#Override
public void onClick(DialogInterface dialogInterface, int i) {
// remove from the master_competitors.json file by overwriting the original file with the new
// global list
File file = new File("data/data/com.checkinsystems.ez_score/files/master_competitors.json");
if (file.exists()) {
FileOutputStream fos = null;
try {
String jsonString = new Gson().toJson(mCompetitorsList);
fos = getActivity().openFileOutput("master_competitors.json", getActivity().MODE_PRIVATE);
fos.write(jsonString.getBytes());
// somehow access the list from the calling activity to remove the item
} catch (IOException e) {
e.printStackTrace();
} finally {
try {
assert fos != null;
fos.close();
} catch (IOException e) {
e.printStackTrace();
}
}
}
}
})
.create();
}
}
And if it helps to understand my code, here is the Singleton class
public class GlobalCompetitorsList {
public static GlobalCompetitorsList sGlobalCompetitorsList;
public static List<Competitor> sCompetitors;
public static GlobalCompetitorsList get() {
if(sGlobalCompetitorsList == null){
return new GlobalCompetitorsList();
} else {
return sGlobalCompetitorsList;
}
}
private GlobalCompetitorsList() {
File file = new File("data/data/com.checkinsystems.ez_score/files/master_competitors.json");
String jsonString;
if(file.exists()){
BufferedReader reader = null;
List<Competitor> list;
sCompetitors = new ArrayList<>();
try {
reader = new BufferedReader(new FileReader(file));
jsonString = reader.readLine();
Type compType = new TypeToken<List<Competitor>>(){}.getType();
list = new Gson().fromJson(jsonString, compType);
addCompetitors(list);
} catch (IOException e) {
e.printStackTrace();
} finally {
try {
assert reader != null;
reader.close();
} catch (IOException e) {
e.printStackTrace();
}
}
} else {
sCompetitors = new ArrayList<>();
}
}
public void addCompetitor(Competitor c){
sCompetitors.add(c);
}
public static void addCompetitors(List<Competitor> c){
sCompetitors.addAll(c);
}
public static List<Competitor> getCompetitors(){
return sCompetitors;
}
}

Simple just create a constructor for the Dialog that you are using
public DeleteCompetitorDialogFragment(IMyListenerCallback listener){
mListener = listener;
}
later on//
if(listener != null){
listener.doWhatYouNeed(stuffToPass);
}
Then make an interface class
public interface IMyListenerCallback{
void doWhatYouNeed(Object stuffToPass);
}
//then in your calling activity
public class MainActivity extends AppCompatActivity implements IMyListenerCallback{
private void launchDialog(){
new DeleteCompetitorDialogFragment(this).show();
}
#Override
public void doWhatYouNeed(Object stuffToPass){
}
}
Of course this is pseduo code and not tested, but hopefully you get the picture. Goodluck.

Loading data from sqlite database with AsyncTask and display inside recyclerview items

I have a Navigation menu with nav menu on it. When clicked on each nav menu, the specific fragment is opened.For example, when I click on Words nav menu, words item display with recyclerView items on it. I'm fetching data from offline and external SQLite database and display on recyclerView items. Now I want to fetch data in another thread, NOT in the main thread, because I want increase loading speed data and app performance. But I don't know how to do this. please help me with a code. I read the same subject on the internet, but I still now have my issue.
this is my AllWordsFragment
public class AllWordsFragment extends Fragment {
private List<WordsList> wordsLists = new ArrayList<>();
private Cursor cursor;
ProgressBar progressBar;
RecyclerView recyclerView;
AllWordsAdapter allWordsAdapter;
#Nullable
#Override
public View onCreateView(LayoutInflater inflater,
#Nullable ViewGroup container, #Nullable Bundle savedInstanceState) {
View view = inflater.inflate(R.layout.all_words_fragment, container, false);
progressBar = view.findViewById(R.id.progressBar);
progressBar.setMax(600);
allWordsAdapter = new AllWordsAdapter(getActivity(), wordsLists);
allWordsAdapter.notifyDataSetChanged();
recyclerView = view.findViewById(R.id.recyclerViewAllWords);
RecyclerView.LayoutManager layoutManager = new LinearLayoutManager(getActivity());
recyclerView.setLayoutManager(layoutManager);
recyclerView.setItemAnimator(new DefaultItemAnimator());
recyclerView.setHasFixedSize(true);
recyclerView.setAdapter(allWordsAdapter);
loadingWords();
return view;
}
private void loadingWords() {
WordDatabase wordDatabase = new WordDatabase(getActivity());
try {
wordDatabase.createDatabase();
wordDatabase.openDatabase();
} catch (SQLiteException e) {
e.printStackTrace();
}
try {
cursor = wordDatabase.QueryData("SELECT Word, Definition, Example, WordList, ImageWord FROM Words");
if (cursor != null && cursor.moveToFirst()) {
do {
WordsList wordList = new WordsList();
wordList.setWordTitle(cursor.getString(0));
wordList.setDefinition(cursor.getString(1));
wordList.setExample(cursor.getString(2));
wordList.setVocubList(cursor.getString(3));
wordList.setImageWord(cursor.getString(4));
wordsLists.add(wordList);
} while (cursor.moveToNext());
wordDatabase.close();
}
} catch (SQLiteException w) {
w.printStackTrace();
} finally {
if (cursor != null) {
cursor.close();
}
}
}
and this is my AllWordsAdapter
public class AllWordsAdapter extends RecyclerView.Adapter {
private int lastPosition = -1;
protected Context context;
private List<WordsList> wordsListList = new ArrayList<>();
public AllWordsAdapter(Context context, List<WordsList> wordsListList) {
this.context = context;
this.wordsListList = wordsListList;
}
#Override
public ViewHolder onCreateViewHolder(ViewGroup parent, int viewType) {
View view = LayoutInflater.from(context).inflate(R.layout.all_words_item, parent, false);
return new ViewHolder(view);
}
#Override
public void onBindViewHolder(final ViewHolder holder, int position) {
WordsList wordsList = wordsListList.get(position);
holder.wordTitle.setText(wordsList.getWordTitle());
holder.definitionWord.setText(Html.fromHtml(wordsList.getDefinition()));
holder.exampleWord.setText(Html.fromHtml(wordsList.getExample()));
holder.labelWordList.setLabelText(wordsList.getVocubList());
//get image from assets with Glide.
String pathImage = wordsList.getImageWord();
String assetsPath = "file:///android_asset/";
Glide.with(context)
.asBitmap()
.load(Uri.parse(assetsPath + "" + pathImage))
.into(holder.wordImage);
Log.d("path", assetsPath + "" + pathImage);
Typeface headerFont = Typeface.createFromAsset(context.getAssets(), "fonts/Roboto-Bold.ttf");
holder.wordTitle.setTypeface(headerFont);
Typeface customFont = Typeface.createFromAsset(context.getAssets(), "fonts/Roboto-Italic.ttf");
holder.exampleWord.setTypeface(customFont);
holder.definitionWord.setTypeface(customFont);
//cal animation function
setAnimation(holder.itemView, position);
holder.relativeLayout.setOnClickListener(new View.OnClickListener() {
#Override
public void onClick(View view) {
Intent intent = new Intent(context, AllWordsDetails.class);
intent.putExtra("word", holder.wordTitle.getText().toString());
context.startActivity(intent);
}
});
}
#Override
public int getItemCount() {
return wordsListList.size();
}
public class ViewHolder extends RecyclerView.ViewHolder {
private CircleImageView wordImage;
private LabelTextView labelWordList;
private TextView wordTitle, definitionWord, exampleWord;
private RelativeLayout relativeLayout;
public ViewHolder(View itemView) {
super(itemView);
wordTitle = itemView.findViewById(R.id.allWordTitle);
wordImage = itemView.findViewById(R.id.circleHeaderImage);
exampleWord = itemView.findViewById(R.id.exampleAllWord);
definitionWord = itemView.findViewById(R.id.definitionAllWord);
labelWordList = itemView.findViewById(R.id.labelWordList);
relativeLayout = itemView.findViewById(R.id.relativeAllWords);
}
}
private void setAnimation(View viewToAnimation, int position) {
// If the bound view wasn't previously displayed on screen, it's animated
if (position > lastPosition) {
ScaleAnimation scaleAnimation = new ScaleAnimation(0.0f, 1.0f, 0.0f, 1.0f,
Animation.RELATIVE_TO_SELF, 0.5f, Animation.RELATIVE_TO_SELF, 0.5f);
scaleAnimation.setDuration(new Random().nextInt(501));//to make duration random number between [0,501)
viewToAnimation.startAnimation(scaleAnimation);
lastPosition = position;
}
}
}
I know must be use AsyncTask and do this in background, but I don't know how do this ? Please help me with a code. Thanks .

create an AsyncTask class inside your class:
class WordLoaderTask extends AsyncTask<Void, Void, Void> {
protected Void doInBackground(Void... params) {
loadingWords();
}
protected void onPostExecute(Void param) {
allWordsAdapter.notifyDataSetChanged();
}
}//asyncClass
replace calling loadingWords() in onCreate() with this line:
new WordLoaderTask().execute();
if you (for some reason or a way of using app) start getting duplicates in your ListView, then add wordsLists.clear(); as first line inside the do{} in loadingWords() method

Try like this
public class AllWordsFragment extends Fragment {
private List<WordsList> wordsLists = new ArrayList<>();
private Cursor cursor;
ProgressBar progressBar;
RecyclerView recyclerView;
AllWordsAdapter allWordsAdapter;
#Nullable
#Override
public View onCreateView(LayoutInflater inflater,
#Nullable ViewGroup container, #Nullable Bundle savedInstanceState) {
View view = inflater.inflate(R.layout.all_words_fragment, container, false);
progressBar = view.findViewById(R.id.progressBar);
progressBar.setMax(600);
allWordsAdapter = new AllWordsAdapter(getActivity(), wordsLists);
allWordsAdapter.notifyDataSetChanged();
recyclerView = view.findViewById(R.id.recyclerViewAllWords);
RecyclerView.LayoutManager layoutManager = new LinearLayoutManager(getActivity());
recyclerView.setLayoutManager(layoutManager);
recyclerView.setItemAnimator(new DefaultItemAnimator());
recyclerView.setHasFixedSize(true);
recyclerView.setAdapter(allWordsAdapter);
loadingWords();
return view;
}
private static LoadWordsTask extends AsyncTask<Void, Void, List<WordsList>> {
private Context context;
private AllWordsAdapter adapter;
private List<WordsList> wordsLists;
public LoadWordsTask(Context context, AllWordsAdapter adapter, List<WordsList> wordsLists) {
this.context = context;
this.adapter = adapter;
this.wordsLists = wordsLists;
}
#Override
public List<WordsList> doInBackground() {
List<WordsList> data = new ArrayList<>();
WordDatabase wordDatabase = new WordDatabase(getActivity());
try {
wordDatabase.createDatabase();
wordDatabase.openDatabase();
} catch (SQLiteException e) {
e.printStackTrace();
}
try {
cursor = wordDatabase.QueryData("SELECT Word, Definition, Example, WordList, ImageWord FROM Words");
if (cursor != null && cursor.moveToFirst()) {
do {
WordsList wordList = new WordsList();
wordList.setWordTitle(cursor.getString(0));
wordList.setDefinition(cursor.getString(1));
wordList.setExample(cursor.getString(2));
wordList.setVocubList(cursor.getString(3));
wordList.setImageWord(cursor.getString(4));
data.add(wordList);
} while (cursor.moveToNext());
wordDatabase.close();
}
} catch (SQLiteException w) {
w.printStackTrace();
} finally {
if (cursor != null) {
cursor.close();
}
}
return data;
}
#Override
public void onPostExecute(List<WordsList> data) {
this.wordsLists.addAll(data);
this.adapter.notifyDataSetChanged();
}
}
}

RecyclerView notifyDatasetChanged not working

I have a RecyclerView inside a Fragment within Activity. I need to refresh my RecyclerView from Activity. I added a method inside Fragment which called notifyDatasetChanged to refresh RecyclerView. But notifyDatasetChanged didn't work.
Here is my Fragment.
public class CategoryFragment extends Fragment{
private RecyclerView recyclerView;
private EventsAdapter adapter;
static Context context = null;
private List<Category> categories;
private List<Item> allItems = new ArrayList();
private ReminderDatabase dbHandler;
#Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
if(!checkDatabase()){
copyDatabase();
}
context = getActivity();
dbHandler = new ReminderDatabase(context);
fillAllItems();
}
public void fillAllItems(){
categories = dbHandler.getAllCategory();
for(int i=0;i<categories.size();i++){
Category category = categories.get(i);
Item categoryItem = new Item(category.getTitle(),category.getColor(),Category.CATEGORY_TYPE);
allItems.add(categoryItem);
List<Event> events = dbHandler.getEventsByCategory(category.getTitle());
for(int j=0;j<events.size();j++){
Event e = events.get(j);
Item eventItem = new Item(e.getId(),e.getTitle(),e.getDescription(),e.getPlace(),e.getCategory(),e.getTime(),e.getDate(),categoryItem.getColor(),e.isShow(),Event.EVENT_TYPE);
allItems.add(eventItem);
}
}
}
#Override
public View onCreateView(LayoutInflater inflater, ViewGroup container,Bundle savedInstanceState) {
View v = inflater.inflate(R.layout.category_fragment, container, false);
recyclerView = (RecyclerView) v.findViewById(R.id.recyclerView);
adapter = new EventsAdapter(getContext(),allItems);
recyclerView.setLayoutManager(new LinearLayoutManager(getActivity()));
recyclerView.setAdapter(adapter);
return v;
}
public boolean checkDatabase(){
String path = "/data/data/com.example.materialdesign.reminder/databases/";
String filename = "Remind";
File file = new File(path+filename);
Log.d("Database","File exists -> "+file.exists());
return file.exists();
}
public void copyDatabase(){
String path = "/data/data/com.example.materialdesign.reminder/databases/Remind";
ReminderDatabase dbHandler = new ReminderDatabase(getContext());
dbHandler.getWritableDatabase();
InputStream fin;
OutputStream fout;
byte[] bytes = new byte[1024];
try {
fin = getActivity().getAssets().open("Remind");
fout = new FileOutputStream(path);
int length=0;
while((length = fin.read(bytes))>0){
fout.write(bytes,0,length);
}
fout.flush();
fout.close();
fin.close();
Log.d("Database","successfully copied database");
} catch (FileNotFoundException e) {
e.printStackTrace();
Log.d("Database","-Error" +e.getMessage());
} catch (IOException e) {
e.printStackTrace();
Log.d("Database","-Error" +e.getMessage());
}
}
#Override
public void onResume() {
super.onResume();
allItems.clear();
Log.d("TAG","onresume");
fillAllItems();
adapter.notifyDataSetChanged();
}
public void refresh(){
Log.d("c",allItems.size()+"");
allItems.clear();
fillAllItems();
Log.d("c",allItems.size()+"");
adapter.notifyDataSetChanged();
}
}
I called refresh method from MainActivity.
#Override
public void onInserted() {
fragment.refresh();
}
My Adapter is here.
public class EventsAdapter extends RecyclerView.Adapter<RecyclerView.ViewHolder>{
private Context context;
private List<Item> allItems = new ArrayList();
private HideOrShowListener hideOrShowListener;
public static final int EVENT_TYPE = 1;
public static final int CATEGORY_TYPE = 0;
private int lastPosition;
private boolean flag = false;
public EventsAdapter(Context context,List<Item> allItems){
this.context = context;
hideOrShowListener =(HideOrShowListener) context;
this.allItems = allItems;
}
#Override
public RecyclerView.ViewHolder onCreateViewHolder(ViewGroup parent, int viewType) {
View view;
switch (viewType){
case CATEGORY_TYPE:
view = LayoutInflater.from(context).inflate(R.layout.category_item,parent,false);
return new CategoryViewHolder(view);
case EVENT_TYPE:
view = LayoutInflater.from(context).inflate(R.layout.events_item,parent,false);
return new EventViewHolder(view);
}
return null;
}
#Override
public void onBindViewHolder(RecyclerView.ViewHolder holder, int position) {
final Item item = allItems.get(position);
switch (item.getType()){
case CATEGORY_TYPE:
((CategoryViewHolder)holder).tvCategoryTitle.setText(item.getTitle());
((GradientDrawable)(((CategoryViewHolder)holder).categoryColorIcon).getBackground()).setColor(Color.parseColor(item.getColor()));
((CategoryViewHolder)holder).imgAddEvent.setOnClickListener(new View.OnClickListener() {
#Override
public void onClick(View v) {
hideOrShowListener.setHideOrShow(item,false);
}
});
break;
case EVENT_TYPE:
String[] time = item.getTime().trim().split(":");
int hour = Integer.parseInt(time[0]);
((EventViewHolder)holder).tvEventName.setText(item.getTitle());
((EventViewHolder)holder).tvTime.setText(hour<12?hour+" : "+time[1] +" am" : hour-12+" : "+time[1] +" pm" );
((EventViewHolder)holder).tvPlace.setText(item.getPlace());
if(item.getDescription().length()==0) {
item.setDescription("No Detail");
}
((EventViewHolder)holder).tvDescription.setText(item.getDescription());
if(item.isShow()){
((EventViewHolder)holder).descriptionLayout.animate().alpha(1).setDuration(200).setInterpolator(new AccelerateInterpolator()).start();
((EventViewHolder)holder).descriptionLayout.setVisibility(View.VISIBLE);
((EventViewHolder)holder).descriptionLayout.setSelected(true);
((EventViewHolder)holder).tvEdit.setVisibility(View.VISIBLE);
((EventViewHolder)holder).eventContainer.setSelected(true);
}else{
((EventViewHolder)holder).descriptionLayout.setVisibility(View.GONE);
((EventViewHolder)holder).descriptionLayout.animate().alpha(0).setDuration(500).start();
((EventViewHolder)holder).descriptionLayout.setSelected(false);
((EventViewHolder)holder).eventContainer.setSelected(false);
((EventViewHolder)holder).tvEdit.setVisibility(View.INVISIBLE);
}
((EventViewHolder)holder).tvEdit.setOnClickListener(new View.OnClickListener() {
#Override
public void onClick(View v) {
hideOrShowListener.setHideOrShow(item,true);
}
});
break;
}
}
#Override
public int getItemCount() {
Log.d("c",allItems.size()+"");
return allItems.size();
}
#Override
public int getItemViewType(int position) {
if(allItems!=null){
return allItems.get(position).getType();
}
return 0;
}
public class CategoryViewHolder extends RecyclerView.ViewHolder{
private TextView tvCategoryTitle;
private View categoryColorIcon;
private ImageView imgAddEvent;
public CategoryViewHolder(View itemView) {
super(itemView);
tvCategoryTitle = (TextView) itemView.findViewById(R.id.tvCategoryTitle);
categoryColorIcon = itemView.findViewById(R.id.categoryColorIcon);
imgAddEvent = (ImageView) itemView.findViewById(R.id.addEvent);
}
}
public class EventViewHolder extends RecyclerView.ViewHolder implements View.OnClickListener {
private LinearLayout descriptionLayout;
private RelativeLayout eventContainer;
private TextView tvEventName,tvTime,tvPlace,tvDescription,tvEdit;
public EventViewHolder(View itemView) {
super(itemView);
descriptionLayout = (LinearLayout) itemView.findViewById(R.id.descriptionLayout);
eventContainer = (RelativeLayout) itemView.findViewById(R.id.eventContainer);
tvEventName = (TextView) itemView.findViewById(R.id.tvEventName);
tvTime = (TextView) itemView.findViewById(R.id.tvTime);
tvPlace = (TextView) itemView.findViewById(R.id.tvPlace);
tvDescription = (TextView) itemView.findViewById(R.id.tvDescription);
tvEdit = (TextView) itemView.findViewById(R.id.tvEdit);
eventContainer.setOnClickListener(this);
}
#Override
public void onClick(View v) {
if(flag){
allItems.get(lastPosition).setShow(false);
}
allItems.get(getAdapterPosition()).setShow(true);
flag = true;
lastPosition = getAdapterPosition();
notifyDataSetChanged();
}
}
public interface HideOrShowListener{
public void setHideOrShow(Item item , boolean isEdit);
}
}
But when I click home button and reenter my application, my RecyclerView refresh. It means that notifyDatasetChanged in onResume method works. But in my refresh method, it doesn't work. How can I do this?

Are you sure this method is being called :
#Override
public void onInserted() {
fragment.refresh();
}
Make sure that you've a correct instance of the fragment. Or you can simply user interface with the refresh() method and implement it in the fragment.