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Android RecyclerView only contain one item after adding items got from asynchronous retrofit calls

I have a recycler view for image display with a simple adapter.
public class ImageListAdapter extends RecyclerView.Adapter<ImageListAdapter.SingleItemRowHolder> {
private ArrayList<Bitmap> itemsList;
public ImageListAdapter(ArrayList<Bitmap> itemsList) {
this.itemsList = itemsList;
}
#Override
public SingleItemRowHolder onCreateViewHolder(ViewGroup viewGroup, int i) {
View v = LayoutInflater.from(viewGroup.getContext()).inflate(R.layout.image_card, null);
return new SingleItemRowHolder(v);
}
#Override
public void onBindViewHolder(SingleItemRowHolder holder, int i) {
Bitmap img = itemsList.get(i);
holder.itemImage.setImageBitmap(img);
}
#Override
public int getItemCount() {
return (null != itemsList ? itemsList.size() : 0);
}
public void addItem(Bitmap image) {
itemsList.add(image);
notifyItemInserted(itemsList.size()-1);
}
public void setItemsList(ArrayList<Bitmap> bmps) {
itemsList = bmps;
}
public ArrayList<Bitmap> getItemsList() {
return itemsList;
}
public void cleanData() {
itemsList = new ArrayList<>();
notifyDataSetChanged();
}
public class SingleItemRowHolder extends RecyclerView.ViewHolder {
protected ImageView itemImage;
public SingleItemRowHolder(View view) {
super(view);
this.itemImage = (ImageView) view.findViewById(R.id.itemImage);
}
}
}
Nothing complex here. Just a simple adapter that getting bitmap list as input and show them in the recycle view.
The point is, the bitmaps are asynchronously added via a retrofit call, as shown in the folloing:
googleMapService.getImageByPhotoReference(s, 300, 300, apiKey).enqueue(new Callback<ResponseBody>() {
#Override
public void onResponse(Call<ResponseBody> call, Response<ResponseBody> response) {
if (response.isSuccessful()) {
if (response.body() != null) {
Bitmap bmp = BitmapFactory.decodeStream(response.body().byteStream());
adapter.addItem(bmp);
}
}
}
});
As you can see here, the bitmap is added to the adapter and the adapter should be able to notify the changes as addItem() contains a notifyItemInserted() call. And this retrofit call is called several times depending on how many times the view model has changes its value (there is a observer observing the change of view model's value. Once the value changes, the above retrofit will get called). So the code that changes view model value look like this:
if (placeDetail.getPhotoRef() != null) {
for (PlaceDetail.PhotoRef ref : placeDetail.getPhotoRef()) {
viewModel.setPhoto(ref.getPhotoRef()); // ref.getPhotoRef returns the photo ref string
}
}
In my expectation, the item list of the adapter should now contains several images. I tried to debug it, and I found when the addItem() method get called, the amount of item list did change as expected. But when it came into the onBindViewHolder() callback, there is only one item left in the item list, which is the first bitmap.
Can anyone tell me why this issue happened? Any suggestion would be appreciated.
---------------------------------- Update --------------------------------
Interesting. I finally found why it only shows one photo. As you can see here, the adapter (id:24856) item list size is 4, which is in my expectation.
However, there is another adapter(id:24962) exists. For that adapter, the add item method only called once thus only one item in that adapter. When the recycler view changes the content, the onBindViewHolder is called on the second adapter. Now my question is, where does the second adapter come from ???
Here is my code to initialize recycler view and adapter
#Override
public View onCreateView(#NonNull LayoutInflater inflater, #Nullable ViewGroup container,
#Nullable Bundle savedInstanceState) {
binding = PlaceFragmentBinding.inflate(getLayoutInflater());
RecyclerView recyclerView = binding.imageGallery;
recyclerView.setHasFixedSize(true);
ImageListAdapter adapter = new ImageListAdapter(new ArrayList<>());
recyclerView.setLayoutManager(new LinearLayoutManager(getContext(), LinearLayoutManager.HORIZONTAL, false));
recyclerView.setAdapter(adapter);
return binding.getRoot();
}

Hej AhSoHard,
did you check if it is a timing issue, because you are loading your data asynchronously and it could lead to missing updates.
also could it be that setItemsList(ArrayList<Bitmap> bmps) is called and overwrites the current list?
is there a reason why you do not use the viewGroup as a base for inflating the layout resource in onCreateViewHolder()?
LayoutInflater.from(viewGroup.getContext()).inflate(R.layout.image_card, viewGroup, false)
in my opinion the Adapter should not be the holder of the current state, maybe have a list outside and use a ListAdapter to display it. When you have a new list of bitmaps, you just call adapter.submit(bitmaps) and the new list will be displayed. Together with a DiffCallback, the old items will not update and the new ones added at the end of the list.

Let's implement the DiffUtils adapter and try to change your calls in this way. As kotlin works as interoperable with java, therefore I am mentioning the gist for an adapter that is written in kotlin.
Check adapter and view holder implementation
Code
ImageListAdapter adapter;
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
binding = PlaceFragmentBinding.inflate(getLayoutInflater());
View view = binding.getRoot();
setContentView(view);
}
#Override
public View onCreateView(#NonNull LayoutInflater inflater, #Nullable ViewGroup container, #Nullable Bundle savedInstanceState) {
binding.imageGallery.setHasFixedSize(true);
adapter = new ImageListAdapter(new ArrayList<>());
binding.imageGallery.setLayoutManager(new LinearLayoutManager(getContext(), LinearLayoutManager.HORIZONTAL, false));
binding.imageGallery.setAdapter(adapter);
return binding.getRoot();
}
Interface googleMapService
Single<ResponseBody> getImageByPhotoReference(_,_,_,_)
Network Call
googleMapService.getImageByPhotoReference(s, 300, 300, apiKey)
.subscribeOn(Schedulers.io())
.observeOn(AndroidSchedulers.mainThread())
.subscribeWith(new DisposableSingleObserver<ResponseBody>() {
#Override
public void onSuccess(ResponseBody response) {
if (response != null) {
Bitmap bmp = BitmapFactory.decodeStream(response.body().byteStream());
adapter.addItem(bmp);
}
}
#Override
public void onError(Throwable e) {
// Do with your error
}
});

It's interesting that you initialize the adapter in onCreateView method and it has local visibility(only visible inside of the onCreateView method). But in the googleMapService.getImageByPhotoReference() method's callback you are referencing it adapter.addItem(bmp);. So my guess is that you are referencing the wrong adapter object in the googleMapService.getImageByPhotoReference() method's callback. The callback may reference an old instance of ImageListAdapter.
Try to initialize ImageListAdapter adapter as a property of your Fragment class and see if it works.

How do I filter Firestore data?

My app allows Users to create Charts, which are stored in the Firestore database like this:
charts
> documentKey1
> description = "Example description"
> name = "Chart name 1"
> uId = user1Id_string
> documentKey2
> description = "Another example description"
> name = "Chart name 2"
> uId = user2Id_string
> documentKey3
> description = "Example description again"
> name = "Chart name 3"
> uId = user1Id_string
Each User can have multiple Charts. Currently, my MainActivity retrieves all of the current user's charts from the database, sorts them into a given order (set by the user), and shows them in a FirebaseRecyclerView within a Fragment.
The MainActivity has 2 Fragments in a ViewPager. The relevant one is FragmentMyCharts which contains:
public class FragmentMyCharts extends FragmentChartsList {
public FragmentMyCharts() {}
public Query getQuery(FirebaseFirestore databaseReference,
String orderBy,
Query.Direction direction) {
// Specify the query which is used to retrieve this user's charts
return databaseReference.collection("charts")
.whereEqualTo("uid", getUid())
.orderBy(orderBy, direction);
}
}
This extends FragmentChartsList, which is as follows:
public abstract class FragmentChartsList extends Fragment {
private FirebaseFirestore mDatabaseRef;
private ChartListAdapter mAdapter;
private RecyclerView mRecycler;
private String mOrder = "name", mFilter;
private Query.Direction mDirection = Query.Direction.DESCENDING;
private TextView mLoadingList, mEmptyList;
public FragmentChartsList() {}
#Override
public View onCreateView(#NonNull LayoutInflater inflater,
ViewGroup container, Bundle savedInstanceState) {
super.onCreateView(inflater, container, savedInstanceState);
// Inflate layout, and find Recycler View which will hold the list
View rootView = inflater.inflate(
R.layout.fragment_charts_list, container, false);
mRecycler = rootView.findViewById(R.id.charts_list);
mRecycler.setHasFixedSize(true);
mLoadingList = rootView.findViewById(R.id.loading_list);
mEmptyList = rootView.findViewById(R.id.empty_list);
// Set up Layout Manager, and set Recycler View to use it
LinearLayoutManager mManager = new LinearLayoutManager(getActivity());
mManager.setReverseLayout(true);
mManager.setStackFromEnd(true);
mRecycler.setLayoutManager(mManager);
// Connect to the database
mDatabaseRef = FirebaseFirestore.getInstance();
setOrderAndFilter(mOrder, mDirection, mFilter);
return rootView;
}
public abstract Query getQuery(FirebaseFirestore databaseReference,
String orderBy,
Query.Direction direction);
public void setOrderAndFilter(String order, Query.Direction direction, String filterString) {
mOrder = order;
mDirection = direction;
mFilter = filterString;
Query mChartsQuery = getQuery(mDatabaseRef, mOrder, mDirection);
// Update recycler options
FirestoreRecyclerOptions<Chart> recyclerOptions = new FirestoreRecyclerOptions.Builder<Chart>()
.setQuery(mChartsQuery, Chart.class)
.build();
mAdapter = new ChartListAdapter(recyclerOptions, getActivity());
mAdapter.startListening();
mRecycler.setAdapter(mAdapter);
mChartsQuery.addSnapshotListener(new EventListener<QuerySnapshot>() {
#Override
public void onEvent(#Nullable QuerySnapshot queryDocumentSnapshots, #Nullable FirebaseFirestoreException e) {
if (queryDocumentSnapshots != null) {
// Hide "loading lists" text
mLoadingList.setVisibility(View.GONE);
if(queryDocumentSnapshots.size() > 0) {
mEmptyList.setVisibility(View.GONE);
mRecycler.setVisibility(View.VISIBLE);
}else {
// If number of Charts = 0,
// if we have filtered, show "no results"
// otherwise, show "no charts"
mEmptyList.setVisibility(View.VISIBLE);
mRecycler.setVisibility(View.GONE);
}
}
}
});
}
This references the ChartListAdapter class, which is defined like this:
public class ChartListAdapter extends FirestoreRecyclerAdapter<Chart, ChartViewHolder> {
private Activity mActivity;
public ChartListAdapter(FirestoreRecyclerOptions<Chart> recyclerOptions, Activity activity) {
super(recyclerOptions);
mActivity = activity;
}
#Override
protected void onBindViewHolder(#NonNull ChartViewHolder holder, int position, #NonNull Chart model) {
final String chartKey = this.getSnapshots().getSnapshot(position).getId();
model.setKey(chartKey);
// Set click listener for the chart
// On click, the user can view the chart
holder.itemView.setOnClickListener(new View.OnClickListener() {
#Override
public void onClick(View v) {
Intent intent = new Intent(mActivity, ActivityViewChart.class);
intent.putExtra("ChartKey", chartKey);
mActivity.startActivity(intent);
}
});
// Implement long-click menu
mActivity.registerForContextMenu(holder.itemView);
// Bind Chart to ViewHolder
holder.bindToChart(model);
}
#NonNull
#Override
public ChartViewHolder onCreateViewHolder(#NonNull ViewGroup parent, int viewType) {
View view = LayoutInflater.from(parent.getContext())
.inflate(R.layout.item_chart, parent, false);
return new ChartViewHolder(view);
}
}
So, currently this retrieves all of the current user's charts, and sorts and displays them. What I want to be able to do is filter the results, so the user can enter some search text, and only charts whose names or descriptions contain that text are shown.
My understanding is that I can't do this as part of the Firestore query, so my idea was to retrieve the full list of charts, and then loop over them all, remove any that don't meet the criteria, and then show the rest (there are unlikely to be hundreds of charts in the list; most users will have around 10).
I can't figure out how to do this, and I'm not even sure whether it's the best way. The obvious place to do it seems to be when I add the snapshotListener to the ChartsQuery in FragmentChartsList, but I can't find a way to remove an individual snapshot from the list. Alternatively, can I put all the items into the recyclerView and then remove the ones that I don't want?
Can anyone point me in the right direction? Everything I've found online seems to be about removing a recyclerView item and deleting it from the database, which I don't want to do.

You can use the following query for search filter functionality.
databaseReference.collection("charts")
.whereEqualTo("uid", getUid())
.orderBy("name")
.startAt(searchText)
.endAt(searchtText + "\uf8ff");
Pass search text to startAt() and endAt() function and name is your documentField.
And pass this query to firestoreAdapter it will provide you with the result record.

How do I update a RecyclerView on sorting the data?

My database (Firestore) stores Charts, created by Users.
On opening the app, the User is shown their own Charts, sorted by Chart Name (this is displayed in a Fragment called MyChartsFragment). They can click a button to change the sort field; this should retrieve the same list of Charts, but sorted by the selected field.
I'm able to pass the new sort field name into MyChartsFragment, but at that point the list of Charts goes blank. I assume I need to redraw it somehow.
The MyChartsFragment is as follows (I've removed most of the try-catch blocks, error checks etc, for clarity):
public class FragmentMyCharts extends FragmentChartsList {
public FragmentMyCharts() {}
public Query getQuery(FirebaseFirestore databaseReference, String orderBy) {
// Specify the query which is used to retrieve this user's charts
return databaseReference.collection("charts")
.whereEqualTo("uid", getUid())
.orderBy(orderBy);
}
}
This extends FragmentChartsList, which contains:
public abstract class FragmentChartsList extends Fragment {
private FirebaseFirestore mDatabaseRef;
private FirestoreRecyclerAdapter<Chart, ChartViewHolder> mAdapter;
private Query mChartsQuery;
private RecyclerView mRecycler;
private String mOrder = "name";
FragmentManager mFragmentManager;
ToolbarFragmentListCharts mFragmentTLC;
public FragmentChartsList() {}
#Override
public View onCreateView(#NonNull LayoutInflater inflater,
ViewGroup container, Bundle savedInstanceState) {
super.onCreateView(inflater, container, savedInstanceState);
// Inflate layout, and find Recycler View to hold the list
View rootView = inflater.inflate(
R.layout.fragment_charts_list, container, false);
mRecycler = rootView.findViewById(R.id.charts_list);
mRecycler.setHasFixedSize(true);
// Set up Layout Manager, and set Recycler View to use it
LinearLayoutManager mManager = new LinearLayoutManager(getActivity());
mManager.setReverseLayout(true);
mManager.setStackFromEnd(true);
mRecycler.setLayoutManager(mManager);
// Connect to the database, and get the appropriate query
mDatabaseRef = FirebaseFirestore.getInstance();
mChartsQuery = getQuery(mDatabaseRef, mOrder);
// Set up Recycler Adapter
FirestoreRecyclerOptions<Chart> recyclerOptions = new FirestoreRecyclerOptions.Builder<Chart>()
.setQuery(mChartsQuery, Chart.class)
.build();
mAdapter = new ChartListAdapter(recyclerOptions, this.getActivity());
// Use Recycler Adapter in RecyclerView
mRecycler.setAdapter(mAdapter);
return rootView;
}
#Override
public void onActivityCreated(Bundle savedInstanceState) {
super.onActivityCreated(savedInstanceState);
// Add listener to charts collection, and deal with any changes by re-showing the list
mChartsQuery.addSnapshotListener(new EventListener<QuerySnapshot>() {
#Override
public void onEvent(#Nullable QuerySnapshot queryDocumentSnapshots,
#Nullable FirebaseFirestoreException e) {
if (queryDocumentSnapshots != null && queryDocumentSnapshots.isEmpty()) {
((MainActivity) Objects.requireNonNull(getActivity())).setPage(1);
}
}
});
}
#Override
public void onStart() {
super.onStart();
mAdapter.startListening();
}
public void setOrderField(String order) {
mOrder = order;
mChartsQuery = getQuery(mDatabaseRef, mOrder);
// Set up Recycler Adapter
FirestoreRecyclerOptions<Chart> recyclerOptions = new FirestoreRecyclerOptions.Builder<Chart>()
.setQuery(mChartsQuery, Chart.class)
.build();
mAdapter = new ChartListAdapter(recyclerOptions, this.getActivity());
// Use Recycler Adapter in RecyclerView
mRecycler.setAdapter(mAdapter);
}
public abstract Query getQuery(FirebaseFirestore databaseReference, String orderBy);
}
So, when the main activity is notified by the toolbar that the sort field has changed, it retrieves the MyChartsFragment (as a FragmentChartsList) and calls the setOrderField function:
public void setOrder(String order) {
FragmentChartsList myCharts = (FragmentChartsList) mPagerAdapter.getItem(0);
myCharts.setOrderField(order);
}
This appears to update the value of mOrder correctly, but then it doesn't re-display the RecyclerView, so I just get a blank space.
What am I doing wrong?
EDITED TO ADD DETAIL:
My ChartListAdapter class is:
public class ChartListAdapter
extends FirestoreRecyclerAdapter<Chart, ChartViewHolder> {
private Activity mActivity;
private FirestoreRecyclerOptions<Chart> recyclerOptions;
public ChartListAdapter(FirestoreRecyclerOptions<Chart> recyclerOptions, Activity activity) {
super(recyclerOptions);
mActivity = activity;
}
#Override
protected void onBindViewHolder(#NonNull ChartViewHolder holder, int position, #NonNull Chart model) {
final String chartKey = this.getSnapshots().getSnapshot(position).getId();
model.setKey(chartKey);
// Set click listener for the chart
holder.itemView.setOnClickListener(new View.OnClickListener() {
#Override
public void onClick(View v) {
Intent intent = new Intent(mActivity, ActivityViewChart.class);
intent.putExtra("ChartKey", chartKey);
mActivity.startActivity(intent);
}
});
// Implement long-click menu
mActivity.registerForContextMenu(holder.itemView);
// Bind Chart to ViewHolder
holder.bindToChart(model);
}
#NonNull
#Override
public ChartViewHolder onCreateViewHolder(#NonNull ViewGroup parent, int viewType) {
View view = LayoutInflater.from(parent.getContext())
.inflate(R.layout.item_chart, parent, false);
return new ChartViewHolder(view);
}
public void setRecyclerOptions(FirestoreRecyclerOptions<Chart> recyclerOptions) {
this.recyclerOptions = recyclerOptions;
}
}

rather then recreating the recyclerView adapter, try updating the options in the adapter.
public void setOrderField(String order) {
mOrder = order;
mChartsQuery = getQuery(mDatabaseRef, mOrder);
// Set up Recycler Adapter
FirestoreRecyclerOptions<Chart> recyclerOptions = new FirestoreRecyclerOptions.Builder<Chart>()
.setQuery(mChartsQuery, Chart.class)
.build();
// Use Recycler Adapter in RecyclerView
mAdapter.setRecyclerOptions(recyclerOptions);
// then call the notify data set changed on the adapter to recreate the recyclerView elements
mAdapter.notifyDataSetChanged();
}
and in the recyclerView adapter class, add a setter for the recyclerOptions :
public void setRecyclerOptions(FirestoreRecyclerOptions<Chart> recyclerOptions) {
this.recyclerOptions = recyclerOptions;
}

Found one problem... I had declared mAdapter with:
private FirestoreRecyclerAdapter<Chart, ChartViewHolder> mAdapter;
when it should have been:
private ChartListAdapter mAdapter;

Solved... in setOrderField I was declaring a new mAdapter, but not listening to it. Once I added
mAdapter.startListening()
it all worked fine!

UPDATE 2021:
I don't know, for how long this new method works, but I'm so thankful for finding it out by myself, because I couldn't find any good response to that:
You don't have to create any Methods in your Adapter anymore.
Simply create the setOrder Method like this:
public FirestoreRecyclerOptions<event_log_Item> getOrder(String order){
String mOrder = order;
Query query = current_productRef.orderBy(mOrder, Query.Direction.DESCENDING);
FirestoreRecyclerOptions<event_log_Item> options = new FirestoreRecyclerOptions.Builder<event_log_Item>().setQuery(query, event_log_Item.class).build();
return options;
}
This Method will return the order-options for the field you want.
Then simply do:
mAdapter.updateOptions(setOrder("Timestamp"));
mAdapter.notifyDataSetChanged();
The Method "updateOptions" is already implemented. Just simply give it the option you want and add "notifyDataSetChanged();"

Non Recycler Fragment calling method on Recycler Adapter? Is this even possible?

Sincere apologies for no code, I'm leaving for a wedding and it was either post code or explain my situation.
I've searched Stack and see many posts for Recycler Adapter to Fragment (that created the adapter) interfaces.
A minor few for Fragment(created the adapter) to Adapter posts but they are not nearly as clear.
My situation is this:
On Main Activity, when App is running:
1) Fragment Lyrics (created the REcycler ADapter that is set into a Lyric Recycler View)
2) Fragment Microphone ( speech recognition microphone functionality and XML icon).
What I want to happen is:
user activates Microphone and speaks, that resulting data is passed to the ADAPTER java file and activates a method on the ADAPTER, causing a visual change to RecyclerView Viewholder on the screen.
Yes, I know this is probably bad architecture. It's for a school project, I'm learning, and I've run out of time.
* What I can do so far *
I have activated the pre-made OnClick listerner for the Adapter (when a user clicks on a View) and OnScroll for the RecyclerView (user scrolls, it fires a method in the Adapter that causes the current View to change).
I have made interface for Passing Speech data from Microphone Fragment, through the Main Activity, to the Lyrics Fragment.
On Main, I simply create an instance of the Lyrics Fragment, then call a custom method on Lyrics Fragment that takes the speech data. Something like this.
LyricsFragment.TakeSpeechData(speech data);
* What my plans was...*
When the speech data arrives on Lyrics Fragment, I thought I could just write something like:
MyRecyclerAdapter.SomeMethodOnAdapter (speech data);
I would be home free at this point.
It doesn't work
No go. I get a null pointer exception here. The MyRecyclerAdapter part of the method call is null. I've looked that up and not sure how to fix it.
I'm assuming I'm referencing the original Adapter that was created when the Fragment layed down the RecyclerView and set everything. It's the same global variable for the Adapter on Fragment Lyrics and I'm assuming it "lives on".
I'm sure I'm missing on fundamental Java principles but i don't know what.
I've spent hours and hours on this trying , reading, researching. I'm totally stuck. Please help.
EDIT: Here is my code for VerseFragment (I'm referring to it as "Lyrics" Fragment in my post). Note this Fragment is loaded, created, and functional with recyclerView on screen. Before the user uses the micrphone fragment, which is also on screen, this has already been created.
public class VersesList extends Fragment {
#BindView(R.id.versesRecycleView) RecyclerView versesRecycleView;
#BindView(R.id.songNameTextView) TextView songName;
#BindView(R.id.artistTextView)TextView artistName;
private SharedPreferences mSharedPreferences;
LinearLayoutManager llm;
List verseList;
List finalModVerseList;
public VerseAdapter verseAdapter;
// temporary
private SharedPreferences.Editor editor;
public VersesList() {
// Required empty public constructor
}
#Override
public View onCreateView(LayoutInflater inflater, ViewGroup container,
Bundle savedInstanceState) {
// Inflate the layout for this fragment
View view = inflater.inflate(R.layout.fragment_verses_list, container, false);
ButterKnife.bind(this, view);
mSharedPreferences = PreferenceManager.getDefaultSharedPreferences(getActivity());
editor=mSharedPreferences.edit();
displayArtistAndSongName();
lyricsToVerseList();
setVersesIntoRecyclerView();
setVersesScrollListener();
//temp
storeAllVerseLevels();
return view;
}
public static VersesList newInstance(String lyrics){
VersesList versesListFragment = new VersesList();
Bundle args = new Bundle();
args.putString("lyrics", lyrics);
versesListFragment.setArguments(args);
return versesListFragment;
}
public void lyricsToVerseList(){
String lyrics = getArguments().getString("lyrics", "");
verseList = new ArrayList<String>();
finalModVerseList = new ArrayList<String>();
verseList= Arrays.asList(lyrics.split("\n"));
int endOfFinalList=verseList.indexOf("...");
for (int i = 0; i < endOfFinalList; i++) {
if(!verseList.get(i).toString().equals("")){
String addThisVerse = verseList.get(i).toString();
//check on length of verse, if too short add next, check again
int numberOfWords = addThisVerse.split(" ").length;
while (numberOfWords < 10 && i < endOfFinalList) {
i++;
addThisVerse += " " + verseList.get(i).toString();
numberOfWords = addThisVerse.split(" ").length;
}
finalModVerseList.add(addThisVerse);
}
}
}
public void displayArtistAndSongName(){
String song = '"'+mSharedPreferences.getString(SONG_NAME, null)+'"';
String artist = "by "+mSharedPreferences.getString(ARTIST_NAME, null);
songName.setText(song);
artistName.setText(artist);
}
public void setVersesIntoRecyclerView(){
verseAdapter = new VerseAdapter(finalModVerseList, (MainActivity)getActivity(), versesRecycleView);
versesRecycleView.setAdapter(verseAdapter);
llm = new LinearLayoutManager(getActivity(),LinearLayoutManager.HORIZONTAL, false);
versesRecycleView.setLayoutManager(llm);
PagerSnapHelper helper = new PagerSnapHelper();
helper.attachToRecyclerView(versesRecycleView);
}
private void storeLevel(int indexNumber) {
editor.putInt(String.valueOf(indexNumber), 1).apply();
}
private void storeAllVerseLevels(){
for (int i=0; i< finalModVerseList.size();i++){
storeLevel(i);
}
for (int j=0; j< finalModVerseList.size();j++){
String level = String.valueOf(mSharedPreferences.getInt(String.valueOf(j), -1));
Log.d("In Shared Preferences ", "Verse "+j+" Level "+level);
}
}
public void checkSpeech(String text){
List<String> temp = new ArrayList<>();
temp.add("test");
VerseAdapter adapter = new VerseAdapter(temp, (MainActivity)getActivity(), versesRecycleView);
try {
adapter.resetVerse();
}catch (NullPointerException e){
Log.d("Null", e.toString());
}
}
public void setVersesScrollListener(){
versesRecycleView.addOnScrollListener(new RecyclerView.OnScrollListener() {
#Override
public void onScrollStateChanged(RecyclerView recyclerView, int newState) {
super.onScrollStateChanged(recyclerView, newState);
if (newState == 0) {
verseAdapter.resetVerse();
}
}
#Override
public void onScrolled(RecyclerView recyclerView, int dx, int dy) {
super.onScrolled(recyclerView, dx, dy);
}
});
}
}
When you are calling the method from your adapter, is MyRecyclerAdapter an instance or the class? To call someMethodOnAdpater(speechData), you must use an instance . Xia is using an instance.
If you need to call an adapter method from within the fragment in which it was created, you can store it in a variable like this.
MyRecyclerAdapter adapter;
#Override
public View onCreateView(...) {
...
adapter = new MyRecyclerAdapter();
myRecyclerView.setAdapter(adapter);
...
}
public void takeSpeechData(String data) {
adapter.someMethodAdapter(data);
}
Edit:
I'm not sure why the same adapter used by your recyclerview is null after being set. Calling an adapter from is definitely possible (I tested a basic example). The code in my example doesn't differ from what you said you had previously, though. I have upvoted your question for visibility.
**Edit: Add Mic Fragment, it has the interface **
package com.blueoxgym.javainthedark.Fragments;
/**
* A simple {#link Fragment} subclass.
*/
public class MicFragment extends Fragment implements View.OnClickListener {
#BindView(R.id.progressBarMic)
ProgressBar micLevels;
#BindView(R.id.btn_mic)
ImageButton btnMicrophone;
private SpeechRecognizer speech = null;
private Intent recognizerIntent;
public final static String TAG = "In speech mode";
public FragmentManager fragmentManager;
private SharedPreferences mSharedPreferences;
private SharedPreferences.Editor mEditor;
private String trackName;
private String artistName;
private CallMainLoadVerseFragment loadVerseFragment;
private CheckSpeech checkSpeechOnVerse;
public MicFragment() {
// Required empty public constructor
}
public static MicFragment newInstance (){
MicFragment micFragment = new MicFragment();
return micFragment;
}
#Override
public View onCreateView(LayoutInflater inflater, ViewGroup container,
Bundle savedInstanceState) {
// Inflate the layout for this fragment
View view = inflater.inflate(R.layout.fragment_mic, container, false);
ButterKnife.bind(this, view);
this.loadVerseFragment = (CallMainLoadVerseFragment) getActivity();
this.checkSpeechOnVerse = (CheckSpeech) getActivity();
btnMicrophone.setOnClickListener(this);
fragmentManager = getFragmentManager();
mSharedPreferences = PreferenceManager.getDefaultSharedPreferences(getActivity());
mEditor = mSharedPreferences.edit();
return view;
}
#Override
public void onClick(View v) {
if (v == btnMicrophone) {
startSpeechToText();
}
}
class listener implements RecognitionListener {
...
#Override
public void onResults(Bundle results) {
String str = new String();
Log.d(TAG, "onResults " + results);
ArrayList<String> data = results.getStringArrayList(SpeechRecognizer.RESULTS_RECOGNITION);
String text = data.get(0).toLowerCase().replace("by","");
Fragment currentFragment = fragmentManager.findFragmentById(R.id.content_frame);
if (currentFragment.toString().contains("LyricSearch")){
searchForSong(text);
} else if (currentFragment.toString().contains("VersesList")){
-----------> Here it is called checkSpeechOnVerse.checkingSpeech(text);
}
}
}
public void startSpeechToText(){
btnMicrophone.setBackgroundResource(R.drawable.circle_green);
speech=SpeechRecognizer.createSpeechRecognizer(getContext());
speech.setRecognitionListener(new listener());
recognizerIntent= new Intent(RecognizerIntent.ACTION_RECOGNIZE_SPEECH);
recognizerIntent.putExtra(RecognizerIntent.EXTRA_LANGUAGE_PREFERENCE, "en-US");
recognizerIntent.putExtra(RecognizerIntent.EXTRA_CALLING_PACKAGE, getActivity().getPackageName());
recognizerIntent.putExtra(RecognizerIntent.EXTRA_LANGUAGE_MODEL,RecognizerIntent.LANGUAGE_MODEL_FREE_FORM);
recognizerIntent.putExtra(RecognizerIntent.EXTRA_MAX_RESULTS, 5);
speech.startListening(recognizerIntent);
}
...
...
public interface CheckSpeech {
void checkingSpeech (String text);
}
}
MainActivity, implements CheckSpeech Interface
public class MainActivity extends AppCompatActivity
implements NavigationView.OnNavigationItemSelectedListener, MicFragment.CallMainLoadVerseFragment, MicFragment.CheckSpeech {
....
...
#Override
public void checkingSpeech(String text) {
VersesList versesList = new VersesList();
--------> Now, I'm pass data from Main to VersesList Fragment(it has the original Adapter)
versesList.checkSpeech(text);
}
VersesList Fragment, where I try to call Adapter
public class VersesList extends Fragment {
....
private VerseAdapter verseAdapter;
setVersesIntoRecyclerView();
....
<---ADAPTER IS MADE AND SET HERE----.
public void setVersesIntoRecyclerView(){
verseAdapter = new VerseAdapter(finalModVerseList, (MainActivity)getActivity(), versesRecycleView);
versesRecycleView.setAdapter(verseAdapter);
llm = new LinearLayoutManager(getActivity(),LinearLayoutManager.HORIZONTAL, false);
versesRecycleView.setLayoutManager(llm);
PagerSnapHelper helper = new PagerSnapHelper();
helper.attachToRecyclerView(versesRecycleView);
}
public void checkSpeech(String text){
-------> NPE NPE
versesAdapter.someMethodOnAdapter(text);
}
public void setVersesScrollListener(){
versesRecycleView.addOnScrollListener(new RecyclerView.OnScrollListener() {
#Override
public void onScrollStateChanged(RecyclerView recyclerView, int newState) {
super.onScrollStateChanged(recyclerView, newState);
if (newState == 0) {
BUT THIS WORKS!!! No NPE. --------> verseAdapter.resetVerse();
}
}
#Override
public void onScrolled(RecyclerView recyclerView, int dx, int dy) {
super.onScrolled(recyclerView, dx, dy);
// VerseAdapter.VerseViewHolder view = versesRecycleView.findViewHolderForAdapterPosition(llm.findFirstVisibleItemPosition());
}
});
}

If you need to call an adapter method from within the fragment in which it was created, you can store it in a variable within that fragment.
MyRecyclerAdapter adapter;
#Override
public View onCreateView(...) {
...
adapter = new MyRecyclerAdapter();
myRecyclerView.setAdapter(adapter);
...
}
public void takeSpeechData(String data) {
adapter.someMethodAdapter(data);
}
Then you can call that method directly from another fragment. (link to accessing fragments)
VersesList versesList = (VersesList) getActivity().getSupportFragmentManager.findFragmentById(containerId);
versesList.takeSpeechData("data");
gif of example

Nested ArrayList while creating RecyclerView

I am developing an android application where i am using a RecyclerView to display a list of items.I am getting the list from server as json.So my problem is within this list i am getting another list as item.That is if my main arraylist contain title and materials, the material is another arraylist.So can you please suggest a solution to display a list within recyclerview.
The code below is my adapter
public class CurriculumAdapter extends RecyclerView.Adapter<RecyclerView.ViewHolder> {
private Context mContext;
private ArrayList<Curriculum> mArrayListCurriculum;
public CurriculumAdapter(Context mContext, ArrayList<Curriculum> mArrayListCurriculum) {
this.mContext = mContext;
this.mArrayListCurriculum = mArrayListCurriculum;
}
#Override
public RecyclerView.ViewHolder onCreateViewHolder(ViewGroup parent, int viewType) {
View v = LayoutInflater.from(parent.getContext()).inflate(R.layout.adapter_key_features, parent,false);
return new KeyFeatureViewHolder(v);
}
#Override
public void onBindViewHolder(RecyclerView.ViewHolder holder, int position) {
if (holder instanceof KeyFeatureViewHolder) {
((KeyFeatureViewHolder) holder).mTextViewFeatureTitle.setText(mArrayListCurriculum.get(position).getTitle());
}
}
#Override
public int getItemCount() {
return mArrayListCurriculum == null ? 0 : mArrayListCurriculum.size();
}
public static class KeyFeatureViewHolder extends RecyclerView.ViewHolder {
public TextView mTextViewFeatureTitle;
public KeyFeatureViewHolder(View itemView) {
super(itemView);
mTextViewFeatureTitle = (TextView) itemView.findViewById(R.id.txtFeature);
}
}
}
The code below is my fragment with dummy arraylist data
public class CourseCurriculumFragment extends Fragment {
private FragmentInterface mFragmentInterface;
private ArrayList<Curriculum> mArrayListCurriculum;
private ArrayList<Material> mArrayListMaterial;
private RecyclerView mRecyclerViewCurriculum;
private LinearLayoutManager mLinearLayoutManager;
private CurriculumAdapter mCurriculumAdapter;
#Override
public View onCreateView(LayoutInflater inflater, #Nullable ViewGroup container, #Nullable Bundle savedInstanceState) {
View view = inflater.inflate(R.layout.fragment_course_curriculum, container, false);
return view;
}
#Override
public void onViewCreated(View view, #Nullable Bundle savedInstanceState) {
super.onViewCreated(view, savedInstanceState);
initView(view);
}
private void initView(View view) {
mArrayListMaterial = new ArrayList<>();
mArrayListCurriculum = new ArrayList<>();
populateMaterials();
populateKeyFeatures();
mRecyclerViewCurriculum = (RecyclerView) view.findViewById(R.id.recyclerViewCurriculum);
mCurriculumAdapter = new CurriculumAdapter(getActivity(), mArrayListCurriculum);
mLinearLayoutManager = new LinearLayoutManager(getActivity());
mRecyclerViewCurriculum.setLayoutManager(mLinearLayoutManager);
mRecyclerViewCurriculum.setAdapter(mCurriculumAdapter);
mRecyclerViewCurriculum.setItemAnimator(new DefaultItemAnimator());
}
private void populateMaterials() {
mArrayListMaterial.add(new Material("12:00","pdf","","Sample Text","0"));
mArrayListMaterial.add(new Material("12:00","pdf","","Sample Text","0"));
}
private void populateKeyFeatures() {
mArrayListCurriculum.add(new Curriculum("UNIT 1",mArrayListMaterial));
mArrayListCurriculum.add(new Curriculum("UNIT 2",mArrayListMaterial));
mArrayListCurriculum.add(new Curriculum("UNIT 3",mArrayListMaterial));
}
}

A bind method in a holder is a good way to pass data to it.
In your case this bind method should take in a Curriculum and a Material object as parameters.
Inside the onBindViewHolder method of the adapter, instead of reaching into the variables of the holder, you should call this bind method.
In the implementation of the method inside the you KeyFeatureViewHolder class you should use these passed parameters and display them in the appropriate UI elements.
Lastly, to get the Material object data into adapter, add ArrayList<Material> as a constructor parameter just like you did with Curriculum.

Use RecyclerView with header, title as header and materials as items of that header. Look at this example.

You need to design a custom list for yourself. For example take an object like this.
public class ListItem {
public curriculumName = null;
public materialName = null;
}
Now populate this list after you parse the JSON string. Get your first Curriculum and populate the object like this
private ArrayList<ListItem> mListItemArray = new ArrayList<ListItem> ();
for(curriculum : mArrayListCurriculum) {
ListItem mListItemHead = new ListItem();
mListItemHead.curriculumName = curriculum.getName();
// Set the header here
mListItemArray.add(mListItemHead);
for(material : curriculum.getMaterials()){
ListItem mListItem = new ListItem();
mListItem.materialName = material.getName();
// Add materials here
mListItemArray.add(mListItem);
}
}
Now, you've a list with headers and materials. When the materialName in your mListItemArray is null, it identifies that this is a header and vice versa.
Now the trick is to modify your adapter of your RecyclerView so that you can bind proper view to your items in your list.
You can find an indication from this answer on how you can achieve this desired behaviour.
Basically, the idea is to modify your getItemViewType to pass the proper view in your onBindViewHolder. Your getItemViewType might look like this.
#Override
public int getItemViewType(int position) {
if (mListItemArray.get(position).curriculumName != null) {
// This is where we'll add header.
return HEADER_VIEW;
}
return super.getItemViewType(position);
}