Develop Reference

My recyclerview doesn't show up when I change my activity

When my app start up the recyclerview loads up. But when I change my activity, like, when i go to ProfileActivity from DashboardActivity and Come back to DashboardActivity the recyclerview vanishes. I don't get the problem.
This part is in onCreate method
recyclerView = findViewById(R.id.recycler_view);
recyclerView.setAdapter(adapter);
adapter.startListening();
LinearLayoutManager layoutManager = new LinearLayoutManager(this);
recyclerView.setHasFixedSize(true);
recyclerView.setLayoutManager(layoutManager);
This is the onStart method
#Override
protected void onStart() {
super.onStart();
Query query = firebaseFirestore.collection("requests")
.orderBy("creationTime", Query.Direction.DESCENDING);
FirestoreRecyclerOptions<Request> options = new FirestoreRecyclerOptions.Builder<Request>()
.setQuery(query, Request.class)
.build();
FirestoreRecyclerAdapter<Request, RequestViewHolder> adapter =
new FirestoreRecyclerAdapter<Request, RequestViewHolder>(options) {
#Override
protected void onBindViewHolder(#NonNull RequestViewHolder holder, int i, #NonNull Request request) {
holder.requestUserNameTV.setText(request.getUser().getFullName());
holder.requestCreationTimeTV.setText(request.getCreationTime());
holder.requestedBloodGroupTV.setText(request.getBloodGroup());
holder.requestLocationTV.setText(request.getLocation());
holder.requestMessageTV.setText(request.getMessage());
}
#NonNull
#Override
public RequestViewHolder onCreateViewHolder(#NonNull ViewGroup parent, int viewType) {
View v = LayoutInflater.from(parent.getContext()).inflate(R.layout.cardview, parent, false);
return new RequestViewHolder(v);
}
};
recyclerView.setAdapter(adapter);
adapter.startListening();
}
This is the ViewHolder
public class RequestViewHolder extends RecyclerView.ViewHolder {
public TextView requestUserNameTV, requestCreationTimeTV, requestedBloodGroupTV;
public TextView requestLocationTV, requestMessageTV;
public LinearLayout ll;
public RequestViewHolder(#NonNull View itemView) {
super(itemView);
ll = itemView.findViewById(R.id.ll);
requestUserNameTV = itemView.findViewById(R.id.requestUserNameTV);
requestCreationTimeTV = itemView.findViewById(R.id.requestCreationTimeTV);
requestedBloodGroupTV = itemView.findViewById(R.id.requestedBloodGroupTV);
requestLocationTV = itemView.findViewById(R.id.requestedLocationTV);
requestMessageTV = itemView.findViewById(R.id.requestMessageTV);
}
}

Move your code from OnStart to OnCreate. it should solve your problem

Now I'm doing it this way. and it works.
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_dashboard);
setUpRecyclerView();
}
private void setUpRecyclerView() {
RecyclerView recyclerView = findViewById(R.id.recycler_view);
recyclerView.setHasFixedSize(true);
RecyclerView.LayoutManager layoutManager = new LinearLayoutManager(this);
firebaseFirestore = FirebaseFirestore.getInstance();
Query query = firebaseFirestore.collection("requests")
.orderBy("creationTime", Query.Direction.DESCENDING);
FirestoreRecyclerOptions<Request> options = new FirestoreRecyclerOptions.Builder<Request>()
.setQuery(query, Request.class)
.build();
FirestoreRecyclerAdapter<Request, RequestViewHolder> adapter =
new FirestoreRecyclerAdapter<Request, RequestViewHolder>(options) {
#Override
protected void onBindViewHolder(#NonNull RequestViewHolder holder, int i, #NonNull Request request) {
holder.requestUserNameTV.setText(request.getUser().getFullName());
holder.requestCreationTimeTV.setText(request.getCreationTime());
holder.requestedBloodGroupTV.setText(request.getBloodGroup());
holder.requestLocationTV.setText(request.getLocation());
holder.requestMessageTV.setText(request.getMessage());
}
#NonNull
#Override
public RequestViewHolder onCreateViewHolder(#NonNull ViewGroup parent, int viewType) {
View v = LayoutInflater.from(parent.getContext()).inflate(R.layout.cardview, parent, false);
RequestViewHolder requestViewHolder = new RequestViewHolder(v);
return requestViewHolder;
}
};
recyclerView.setLayoutManager(layoutManager);
recyclerView.setAdapter(adapter);
adapter.startListening();
}

Searching in Firebase Null with onClick Listener

I am trying to search for the information in my firebase db, and I am not able to do so.
This is the class in which I'm searching from:
private FirebaseRecyclerAdapter<DjProfile, ResultsViewHolder> firebaseRecyclerAdapter;
public static Query query;
public static String searchData;
DatabaseReference mProfileDatabase;
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_attendee_landing);
Toolbar toolbar = findViewById(R.id.toolbar);
setSupportActionBar(toolbar);
final RecyclerView recyclerView = findViewById(R.id.results_recycler);
recyclerView.setLayoutManager(new LinearLayoutManager(this));
final EditText t = (EditText) findViewById(R.id.DjNameET);
mProfileDatabase = FirebaseDatabase.getInstance().getReference();
t.setOnEditorActionListener(new TextView.OnEditorActionListener() {
#Override
public boolean onEditorAction(TextView textView, int i, KeyEvent keyEvent) {
if(i == EditorInfo.IME_ACTION_SEARCH)
{
searchData = t.getText().toString();
return true;
}
return false;
}
});
ImageButton imgB= (ImageButton) findViewById(R.id.searchBtn);
imgB.setOnClickListener(new View.OnClickListener(){
#Override
public void onClick(View view)
{
query = mProfileDatabase.orderByChild("djprofile")
.startAt(searchData)
.endAt(searchData + "\uf8ff");
}
});
FirebaseRecyclerOptions<DjProfile> firebaseRecyclerOptions = new FirebaseRecyclerOptions.Builder<DjProfile>()
.setQuery(query, DjProfile.class)
.build();
firebaseRecyclerAdapter = new FirebaseRecyclerAdapter<DjProfile, ResultsViewHolder>(firebaseRecyclerOptions)
{
#NonNull
#Override
public ResultsViewHolder onCreateViewHolder(#NonNull ViewGroup viewGroup, int i) {
View view = LayoutInflater.from(viewGroup.getContext()).inflate(R.layout.searchitem_list, viewGroup, false);
return new ResultsViewHolder(view);
}
#Override
protected void onBindViewHolder(#NonNull ResultsViewHolder holder, int position, #NonNull DjProfile model) {
holder.setDjProfile(model);
}
};
recyclerView.setAdapter(firebaseRecyclerAdapter);
}
#Override
protected void onStart()
{
super.onStart();
firebaseRecyclerAdapter.startListening();
}
Here is the exception I am getting: (says to be occuring in the onStart() method)
java.lang.NullPointerException: Attempt to invoke virtual method 'com.google.firebase.database.ChildEventListener com.google.firebase.database.Query.addChildEventListener(com.google.firebase.database.ChildEventListener)' on a null object reference
Any help as to why this is null would be greatly appreciated!

To be able to initialize the adapter, you need to have a valid query. And to be able to create the query, you need to have the searchData. This means that the initialization of the firebaseRecyclerAdapter should happen inside the onClick.
imgB.setOnClickListener(new View.OnClickListener(){
#Override
public void onClick(View view)
{
query = mProfileDatabase.orderByChild("djprofile")
.startAt(searchData)
.endAt(searchData + "\uf8ff");
FirebaseRecyclerOptions<DjProfile> firebaseRecyclerOptions = new FirebaseRecyclerOptions.Builder<DjProfile>()
.setQuery(query, DjProfile.class)
.build();
firebaseRecyclerAdapter = new FirebaseRecyclerAdapter<DjProfile, ResultsViewHolder>(firebaseRecyclerOptions)
{
#NonNull
#Override
public ResultsViewHolder onCreateViewHolder(#NonNull ViewGroup viewGroup, int i) {
View view = LayoutInflater.from(viewGroup.getContext()).inflate(R.layout.searchitem_list, viewGroup, false);
return new ResultsViewHolder(view);
}
#Override
protected void onBindViewHolder(#NonNull ResultsViewHolder holder, int position, #NonNull DjProfile model) {
holder.setDjProfile(model);
}
};
recyclerView.setAdapter(firebaseRecyclerAdapter);
}
});

FirebaseRecyclerAdapter not rendering anything on the recyclerview

I've checked each and every bit of code in order to successfully render the data on recyclerview from Firebase, but still cannot figure out the problem.
Nothing is show on the logcat when I use Log.d for getting the children of the snapshot(means line is not executed). Can anybody point out the error.
public class MyOrders extends AppCompatActivity {
private static final String TAG = "MyOrders";
DatabaseReference databaseReference;
FirebaseRecyclerAdapter firebaseRecyclerAdapter;
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_my_orders);
RecyclerView myOrderList = findViewById(R.id.myOrderList);
Query query = FirebaseDatabase.getInstance().getReference("Requests").orderByChild("name").equalTo(User.currentUser.getUserName());
FirebaseRecyclerOptions<Request> options = new FirebaseRecyclerOptions.Builder<Request>().setQuery(query, new SnapshotParser<Request>() {
#NonNull
#Override
public Request parseSnapshot(#NonNull DataSnapshot snapshot) {
Log.d(TAG, "onCreate: "+snapshot.getChildrenCount());
return new Request(snapshot.child("name").getValue().toString(), snapshot.child("phone").getValue().toString(), snapshot.child("address").getValue().toString(), snapshot.child("total").getValue().toString());
}
}).build();
firebaseRecyclerAdapter = new FirebaseRecyclerAdapter<Request, MyOrdersViewHolder>(options){
#NonNull
#Override
public MyOrdersViewHolder onCreateViewHolder(#NonNull ViewGroup viewGroup, int i) {
View v = LayoutInflater.from(viewGroup.getContext()).inflate(R.layout.my_order_template, viewGroup, false);
return new MyOrdersViewHolder(v);
}
#Override
protected void onBindViewHolder(#NonNull MyOrdersViewHolder holder, int position, #NonNull Request model) {
Log.d(TAG, "onCreate: "+position);
holder.setOrder_id(firebaseRecyclerAdapter.getRef(position).getKey());
holder.setOrder_status(model.getOrderStatus());
holder.setOrder_items(model.getRequestedOrderList().size()+"");
holder.setItemClickLitener(new ItemClickLitener() {
#Override
public void onClick(View v, int pos, boolean isLongClick) {
Toast.makeText(MyOrders.this, ""+"Pending Action", Toast.LENGTH_SHORT).show();
}
});
}
};
myOrderList.setAdapter(firebaseRecyclerAdapter);
}
#Override
protected void onStart() {
super.onStart();
firebaseRecyclerAdapter.startListening();
}
#Override
protected void onStop() {
super.onStop();
firebaseRecyclerAdapter.stopListening();
}
}

How to use AutocompleteTextview with Firebase recycler adapter

I've been searching about autocomplete textview but I can't seem figure out how can i implement it in firebase recycler adapter ? I saw this thread: How can I load an AutoCompleteTextView from a list of Firebase data?
But I don't know how I can implement it in my program .
Here's my portion of my code ,
private void firebaseUserSearch(String searchText) {
String spinnerSearchs=spinnerSearch.getSelectedItem().toString();
Toast.makeText(getActivity(), "Started Search", Toast.LENGTH_LONG).show();
if(spinnerSearchs.equals("Book Title")){
Query firebaseQuerySearch = mBookDatabase.orderByChild("bookTitle").startAt(searchText).endAt(searchText + "\uf8ff");
FirebaseRecyclerOptions bookOptions= new FirebaseRecyclerOptions.Builder<Book>().setQuery(firebaseQuerySearch,Book.class).build();
mBook = new FirebaseRecyclerAdapter<Book, UsersViewHolder>(bookOptions) {
#Override
protected void onBindViewHolder(final UsersViewHolder holder, final int position,final Book model) {
holder.setDetails(model.getBookId(),model.getBookTitle(),model.getAuthorName());
holder.setItemClickListener(new ItemClickListener() {
#Override
public void OnClick(View view, int position, boolean isLongClick) {
Intent intent = new Intent(getActivity().getBaseContext(),Borrow.class);
intent.putExtra(BOOK_ID,model.getBookId());
getActivity().startActivity(intent);
}
});
holder.setIsRecyclable(false);
}
#Override
public UsersViewHolder onCreateViewHolder(ViewGroup parent, int viewType) {
View view = LayoutInflater.from(parent.getContext()).inflate(R.layout.book_layout,parent,false);
return new UsersViewHolder(view,bookList);
}
};
mSearchList.setAdapter(mBook);
} else if(spinnerSearchs.equals("Author")){
Query firebaseQuerySearch = mBookDatabase.orderByChild("authorName").startAt(searchText).endAt(searchText + "\uf8ff");
FirebaseRecyclerOptions bookOptions= new FirebaseRecyclerOptions.Builder<Book>().setQuery(firebaseQuerySearch,Book.class).build();
mBook = new FirebaseRecyclerAdapter<Book, UsersViewHolder>(bookOptions) {
#Override
protected void onBindViewHolder(final UsersViewHolder holder, final int position,final Book model) {
holder.setDetails(model.getBookId(),model.getBookTitle(),model.getAuthorName());
holder.setItemClickListener(new ItemClickListener() {
#Override
public void OnClick(View view, int position, boolean isLongClick) {
Intent intent = new Intent(getActivity().getBaseContext(),Borrow.class);
intent.putExtra(BOOK_ID,model.getBookId());
getActivity().startActivity(intent);
}
});
holder.setIsRecyclable(false);
}
#Override
public UsersViewHolder onCreateViewHolder(ViewGroup parent, int viewType) {
View view = LayoutInflater.from(parent.getContext()).inflate(R.layout.book_layout,parent,false);
return new UsersViewHolder(view,bookList);
}
};
mSearchList.setAdapter(mBook);
}
mBook.startListening();
}

Getting onClickListener on RecyclerView with Firebase in Android

I have implemented RecyclerView with Firebase RecyclerAdapter in my activity and want to get onClickListener implemented to it although I have tried to achieve this but something is not right in my code I guess, please help me find what is wrong.I have searched another questions but did not got the understanding and cant find the solution to my problem.
I am using Android Studio
firebase Adapter class file:
public class HomePage extends AppCompatActivity {
#Override
public void onStart() {
super.onStart();
FirebaseUser currentUser = mAuth.getCurrentUser();
if (currentUser == null) {
sentToStart();
}
FirebaseRecyclerAdapter<post, postViewHolder> firebaseRecyclerAdapter = new FirebaseRecyclerAdapter<post, postViewHolder>(
post.class,
R.layout.post_row_recycle_home,
postViewHolder.class,
mDatabaseReference
) {
#Override
protected void populateViewHolder(postViewHolder viewHolder, post model, int position) {
viewHolder.setwebViewPost(model.getWebViewPost());
}
};
mrecyclerView.setAdapter(firebaseRecyclerAdapter);
}
public static class postViewHolder extends RecyclerViewPager.ViewHolder {
View mView;
public postViewHolder(View itemView) {
super(itemView);
mView = itemView;
mView.setOnClickListener(new View.OnClickListener() {
#Override
public void onClick(View v) {
mClickListener.onItemClick(v, getAdapterPosition());
}
});
}
private postViewHolder.ClickListener mClickListener;
public interface ClickListener {
public void onItemClick(View view, int position);
}
public void setOnClickListener(postViewHolder.ClickListener clickListener) {
mClickListener = clickListener;
}
public void setwebViewPost(String webViewPost) {
WebView webView = (WebView) mView.findViewById(R.id.webView_news);
webView.loadUrl(webViewPost);
}
}
#Override
public postViewHolder onCreateViewHolder(ViewGroup parent, int viewType) {
postViewHolder viewHolder = super.onCreateViewHolder(parent, viewType);
viewHolder.setOnClickListener(new postViewHolder().ClickListener() {
#Override
public void onItemClick (View view,int position){
Toast.makeText(this, "Item clicked at " + position, Toast.LENGTH_SHORT).show();
}
});
return viewHolder;
}

Move the onClickListener inside onBindViewHolder.
#Override
public void onBindViewHolder(RecyclerView.ViewHolder holder, int position) {
holder.itemView.setOnClickListener(new postViewHolder().ClickListener() {
#Override
public void onItemClick (View view,int position){
Toast.makeText(this, "Item clicked at " + position, Toast.LENGTH_SHORT).show();
}
});
}
EDIT:
Remove the interface because it's redundant.Your are passing the value from viewholder to onCreateViewHolder which is unnecessary. Instead handle the click inside viewholder. Check the updated class.
public class HomePage extends AppCompatActivity {
#Override
public void onStart() {
super.onStart();
FirebaseUser currentUser = mAuth.getCurrentUser();
if (currentUser == null) {
sentToStart();
}
FirebaseRecyclerAdapter<post, postViewHolder> firebaseRecyclerAdapter = new FirebaseRecyclerAdapter<post, postViewHolder>(post.class, R.layout.post_row_recycle_home, postViewHolder.class, mDatabaseReference) {
#Override
protected void populateViewHolder(postViewHolder viewHolder, post model, int position) {
viewHolder.setwebViewPost(model.getWebViewPost());
}
};
mrecyclerView.setAdapter(firebaseRecyclerAdapter);
}
public static class postViewHolder extends RecyclerViewPager.ViewHolder {
View mView;
public postViewHolder(View itemView) {
super(itemView);
itemView.setOnClickListener(new View.OnClickListener() {
#Override
public void onClick(View v) {
//Show the webViewPost Here
}
});
}
public void setwebViewPost(String webViewPost) {
WebView webView = (WebView) mView.findViewById(R.id.webView_news);
webView.loadUrl(webViewPost);
}
}
#Override
public postViewHolder onCreateViewHolder(ViewGroup parent, int viewType) {
postViewHolder viewHolder = super.onCreateViewHolder(parent, viewType);
return viewHolder;
}
}

Please see my approach which was taken from Google samples + GoogleIO youtube sessions:
Use:
onCreateViewHolder(ViewGroup parent, int viewType)
newsAdapter = new FirebaseRecyclerAdapter<ModelNews, NewsItemHolder>(
ModelNews.class,
R.layout.item_news,
NewsItemHolder.class,
FirebaseDatabase.getInstance()
.getReference(FIREBASE_NEWS)
.orderByChild(FIREBASE_ORDER_BY_FIELD)
.limitToFirst(20)) {
#Override
public NewsItemHolder onCreateViewHolder(ViewGroup parent, int viewType) {
View view = LayoutInflater.from(parent.getContext()).inflate(viewType, parent, false);
final NewsItemHolder newsItemHolder = new NewsItemHolder(view);
newsItemHolder.holder.setOnClickListener(new View.OnClickListener() {
#Override
public void onClick(View v) {
int pos = newsItemHolder.getAdapterPosition();
if (pos != RecyclerView.NO_POSITION) {
ModelNews clicked = newsAdapter.getItem(pos);
if (clicked.getIsExternal() && !hasConnection) {
showSnackbar(R.string.news_with_wifi);
return;
}
goToDetails(clicked.getID(), clicked.getIsExternal());
}
}
});
return newsItemHolder;
}
#Override
public void populateViewHolder(
final NewsItemHolder view,
ModelNews data,
final int position) {
// Set news title
view.titleView.setText(data.getTitle());
// hide OR show wifi icon
view.needWifiIcon(data.getIsExternal());
// Set news image
mImageLoader.loadImage(data.getThumbUrl(), view.thumbView, true);
// Set news description
view.descView.setText(data.getContent());
}
#Override
public void onDataChanged() {
if (newsProgessBar.getVisibility() != View.GONE) {
newsProgessBar.setVisibility(GONE);
}
}
};