I have a NavigationDrawer activity which is using fragments. In one of my fragments I want to load data from the Firebase database to a RecyclerView.
So I have an ArrayList for the objects I have stored in the database. Then I add a ValueEventListener to my database reference where I add the objects from the database to the array list. And then I give the ArrayList to the RecyclerView Adapter which should create the list with my objects.
When I use addListenerForSingleValueEvent it is never working, I always get an empty RecyclerView. When I use addValueEventListener it is working neither at the start, but when I switch the orientation of my phone to landscape the data suddenly appears. And if I go back to the normal orientation it is still there. But not at the start when I open the fragment.
Here is my code of the fragment class:
public class LogFragment extends Fragment {
private RecyclerView recyclerView;
private RecyclerView.Adapter rvAdapter;
private RecyclerView.LayoutManager rvLayoutManager;
private ArrayList<LogEntry> entries;
private DatabaseReference databaseReference;
private DatabaseReference logReference;
private FirebaseAuth firebaseAuth;
private FirebaseUser firebaseUser;
public LogFragment() {
// Required empty public constructor
}
#Override
public View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState) {
View rootView = inflater.inflate(R.layout.fragment_log, container, false);
databaseReference = FirebaseDatabase.getInstance().getReference();
firebaseAuth = FirebaseAuth.getInstance();
firebaseUser = firebaseAuth.getCurrentUser();
loadEntries();
recyclerView = (RecyclerView) rootView.findViewById(R.id.recyclerView);
rvLayoutManager = new LinearLayoutManager(getActivity());
recyclerView.setLayoutManager(rvLayoutManager);
rvAdapter = new RvAdapter(entries);
recyclerView.setAdapter(rvAdapter);
// Inflate the layout for this fragment
return rootView;
}
private void loadEntries(){
entries = new ArrayList<>();
logReference = databaseReference.child("log").child(firebaseUser.getUid());
ValueEventListener valueEventListener = new ValueEventListener() {
#Override
public void onDataChange(DataSnapshot dataSnapshot) {
for(DataSnapshot ds : dataSnapshot.getChildren()){
entries.add(ds.getValue(LogEntry.class));
}
}
#Override
public void onCancelled(DatabaseError databaseError) {
Log.w("LogFragment", "loadLog:onCancelled", databaseError.toException());
}
};
logbuchReference.addValueEventListener(valueEventListener);
}
}
And here is my RvAdapter.java:
public class RvAdapter extends RecyclerView.Adapter<RvAdapter.MyViewHolder> {
private ArrayList<LogEntry> entries;
public RvAdapter(ArrayList<LogEntry> entries){
this.entries = entries;
}
#Override
public MyViewHolder onCreateViewHolder(ViewGroup parent, int viewType) {
View itemView = LayoutInflater.from(parent.getContext()).inflate(R.layout.log_entry_item, null);
return new MyViewHolder(itemView);
}
#Override
public void onBindViewHolder(MyViewHolder holder, int position) {
SimpleDateFormat dateFormat = new SimpleDateFormat("dd.MM.yyyy");
SimpleDateFormat timeFormat = new SimpleDateFormat("HH:mm");
holder.tvAction.setText(entries.get(position).action);
holder.tvDate.setText(dateFormat.format(entries.get(position).date)+"\n"+timeFormat.format(entries.get(position).date));
holder.ivIcon.setImageResource(entries.get(position).icon);
holder.itemView.setOnClickListener(new View.OnClickListener(){
#Override
public void onClick(View v) {
// Do something
}
});
}
#Override
public int getItemCount() {
return entries.size();
}
public class MyViewHolder extends RecyclerView.ViewHolder {
TextView tvAction, tvDate;
ImageView ivIcon;
public MyViewHolder(View itemView) {
super(itemView);
tvAction = (TextView) itemView.findViewById(R.id.tvAction);
tvDate = (TextView) itemView.findViewById(R.id.tvDate);
ivIcon = (ImageView) itemView.findViewById(R.id.ivIcon);
}
}
}
And here my LogEntry.java:
public class LogEntry {
public String action;
public Date date;
public int icon;
public String message;
public LogEntry() {}
public LogEntry(String action, Date date, int icon, String message) {
this.action = action;
this.date = date;
this.icon = icon;
this.message = message;
}
}
Someone know what could be the problem?
EDIT:
When I System.out.prinln the ArrayList right after the for() I get the data. So loading the data from the database is working. But presenting the data is not working.
Firebase is asynchronous. Set or notify the adapter from within the callback.
ValueEventListener valueEventListener = new ValueEventListener() {
#Override
public void onDataChange(DataSnapshot dataSnapshot) {
for(DataSnapshot ds : dataSnapshot.getChildren()){
entries.add(ds.getValue(LogEntry.class));
}
// Declare adapter and set here
// OR... adapter.notifyDataSetChanged();
}
#Override
public void onCancelled(DatabaseError databaseError) {
Log.w("LogFragment", "loadLog:onCancelled", databaseError.toException());
}
};
In more detail,
loadEntries(); // ... Doing stuff in the background
recyclerView = (RecyclerView) rootView.findViewById(R.id.recyclerView);
rvLayoutManager = new LinearLayoutManager(getActivity());
recyclerView.setLayoutManager(rvLayoutManager);
rvAdapter = new RvAdapter(entries); // This is still empty, probably
recyclerView.setAdapter(rvAdapter);
// entries.add() called later, but adapter never notified
You can use https://github.com/firebase/FirebaseUI-Android to solve this problem.
follow a little code to help you...
ListView messagesView = (ListView) findViewById(R.id.messages_list);
DatabaseReference ref = FirebaseDatabase.getInstance().getReference();
mAdapter = new FirebaseListAdapter<Chat>(this, Chat.class, android.R.layout.two_line_list_item, ref) {
#Override
protected void populateView(View view, Chat chatMessage, int position) {
((TextView)view.findViewById(android.R.id.text1)).setText(chatMessage.getName());
((TextView)view.findViewById(android.R.id.text2)).setText(chatMessage.getText());
}
};
messagesView.setAdapter(mAdapter);
Good luck!!!
Related
My recyclerview always reset to first position after new data is inserted to firebase. In my TestAdapter class, I have an onClickListener which increments like on a post when clicked. Whenever I click on this "like" button, view is reset to first position. I believe this issue is related to setAdapter() being called on data changed. Please help!
MainActivity fetches "post" data from Firebase and populates it in TestAdapter class.
public class MainActivity extends AppCompatActivity {
private RecyclerView recyclerView;
private TestAdapter testAdapter;
private ArrayList<Post> postList;
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
recyclerView = findViewById(R.id.recyclerView);
recyclerView.setLayoutManager(new LinearLayoutManager(this));
fetchPostFromDB();
}
private void fetchPostFromDB() {
DatabaseReference databaseRef = FirebaseDatabase.getInstance().getReference("Post");
databaseRef.addValueEventListener(new ValueEventListener() {
#Override
public void onDataChange(#NonNull DataSnapshot snapshot) {
postList = new ArrayList<>();
for (DataSnapshot snap : snapshot.getChildren()) {
String post = snap.child("post").getValue().toString();
Post post = new Post(post);
postList.add(post);
}
testAdapter = new TestAdapter(getApplicationContext(), postList);
recyclerView.setAdapter(testAdapter);
}
#Override
public void onCancelled(#NonNull DatabaseError error) {
}
});
}
TestAdapter binds the data (postList) and has an onClickListener.
public class TestAdapter extends RecyclerView.Adapter<TestAdapter.TestHolder> {
private List<Post> postList;
private Context context;
private DatabaseReference databaseReference;
public TestAdapter(Context ct, ArrayList<Post> postList) {
context = ct;
this.postList = postList;
}
#NonNull
#Override
public TestHolder onCreateViewHolder(#NonNull ViewGroup parent, int viewType) {
LayoutInflater layoutInflater = LayoutInflater.from(context);
View view = layoutInflater.inflate(R.layout.post_item, parent, false);
final TestHolder holder = new TestHolder(view);
holder.ibLike.setOnClickListener(new View.OnClickListener() {
#Override
public void onClick(View view) {
String postID = postList.get(holder.getAdapterPosition()).getPostID();
databaseReference = FirebaseDatabase.getInstance().getReference("Posts").child(postID).child("likes");
int incrementLike = postList.get(holder.getAdapterPosition()).getLikes() + 1;
databaseReference.setValue(incrementLike);
}
});
return holder;
}
#Override
public void onBindViewHolder(#NonNull final TestHolder holder, final int position) {
holder.tvPost.setText(postList.get(position).getPost());
holder.tvVotes.setText(Integer.toString(postList.get(position).getLikes()));
}
#Override
public int getItemCount() {
return postList.size();
}
public static class TestHolder extends RecyclerView.ViewHolder {
TextView tvPost, tvLikes;
ImageButton ibLike;
public TestHolder(#NonNull View itemView) {
super(itemView);
tvPost = itemView.findViewById(R.id.tvPost);
tvLikes = itemView.findViewById(R.id.tvLikes);
ibLike = itemView.findViewById(R.id.ibLike);
}
}
Here need to initialize your adapter class from main activity. and then when data received just call adapter.notifiyDatasetChanged like:
onCreate():
postList = new ArrayList<>();
recyclerView = findViewById(R.id.recyclerView);
recyclerView.setLayoutManager(new LinearLayoutManager(this));
testAdapter = new TestAdapter(getApplicationContext(), postList);
recyclerView.setAdapter(testAdapter);
and from your fetchPostFromDB delete adapter initialization insted of this just put this line testAdapter.notifiyDataSetChanged()
And when click on text button you can update/handle like this:
holder.ibLike.setOnClickListener(new View.OnClickListener() {
#Override
public void onClick(View view) {
String postID = postList.get(holder.getAdapterPosition()).getPostID();
databaseReference = FirebaseDatabase.getInstance().getReference("Posts").child(postID).child("likes");
int incrementLike = postList.get(holder.getAdapterPosition()).getLikes() + 1;
postList.get(holder.getAdapterPosition()).setLikes(incrementLike);
databaseReference.setValue(incrementLike);
notifyDataSetChanged();
}
});
I try to implement a friend request feature in the fragment using custom adapter with firebase database. The problem is when a user accepts or delete someone request, it deletes from firebase but not properly update in the RecyclerView. this problems occurred in only runtime. If I refresh the page then my problem goes away.
Let I have two friend request. If I delete 2nd data then 2nd data will gone from RecyclerView but the problem is RecyclerView shows 1st data doubles. and if I delete 1st data then 1st data goes in the 2nd row and 2nd data came into the first row.
here is my database screenshot
Fragment class-
public class NotificationFragment extends Fragment {
private RecyclerView NotificationRecyclerView;
private NotificationAdapter adapter;
private List<Friend> friendList;
public NotificationFragment() {
// 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_notification, container, false);
NotificationRecyclerView = view.findViewById(R.id.NotificationRecyclerView);
NotificationRecyclerView.setHasFixedSize(true);
LinearLayoutManager LayoutManager = new LinearLayoutManager(getContext());
NotificationRecyclerView.setLayoutManager(LayoutManager);
friendList = new ArrayList<>();
adapter = new NotificationAdapter(getContext(), friendList);
NotificationRecyclerView.setAdapter(adapter);
readAllNotification();
return view;
}
private void readAllNotification() {
final FirebaseUser firebaseUser = FirebaseAuth.getInstance().getCurrentUser();
DatabaseReference reference = FirebaseDatabase.getInstance().getReference("FriendRequest");
reference.addValueEventListener(new ValueEventListener() {
#Override
public void onDataChange(#NonNull DataSnapshot dataSnapshot) {
for (DataSnapshot snapshot : dataSnapshot.getChildren()) {
Friend friend = snapshot.getValue(Friend.class);
if (firebaseUser.getUid().equals(friend.getReceiverID())) {
friendList.add(friend);
}
}
Collections.reverse(friendList);
adapter.notifyDataSetChanged();
}
#Override
public void onCancelled(#NonNull DatabaseError databaseError) {
}
});
}
}
Custom Adapter -
public class NotificationAdapter extends RecyclerView.Adapter<NotificationAdapter.NotificationViewHolder> {
private Context context;
private List<Friend> friendList;
public NotificationAdapter(Context context, List<Friend> friendList) {
this.context = context;
this.friendList = friendList;
}
#NonNull
#Override
public NotificationViewHolder onCreateViewHolder(#NonNull ViewGroup parent, int viewType) {
View view = LayoutInflater.from(context).inflate(R.layout.single_notification_item, parent, false);
return new NotificationAdapter.NotificationViewHolder(view);
}
#Override
public void onBindViewHolder(#NonNull final NotificationViewHolder holder, final int position) {
final Friend friend = friendList.get(position);
getUserInfo(holder.profileImage, holder.NotificationUserName, friend.getSenderID());
holder.cancelRequestButton.setOnClickListener(new View.OnClickListener() {
#Override
public void onClick(View v) {
FirebaseDatabase.getInstance().getReference("FriendRequest")
.child(friend.getRequestID()).removeValue().addOnCompleteListener(new OnCompleteListener<Void>() {
#Override
public void onComplete(#NonNull Task<Void> task) {
removeItem(position);
Toast.makeText(context, "removed", Toast.LENGTH_SHORT).show();
}
});
}
});
}
public void removeItem(int position) {
friendList.remove(position);
notifyDataSetChanged();
}
#Override
public int getItemCount() {
return friendList.size();
}
private void getUserInfo(final CircleImageView prfileImage, final TextView NotificationUserName, String senderID) {
DatabaseReference reference = FirebaseDatabase.getInstance().getReference("Users").child(senderID);
reference.addValueEventListener(new ValueEventListener() {
#Override
public void onDataChange(#NonNull DataSnapshot dataSnapshot) {
Users users = dataSnapshot.getValue(Users.class);
NotificationUserName.setText(users.getUserName());
Picasso.with(context).load(users.getImageUrl()).into(prfileImage);
}
#Override
public void onCancelled(#NonNull DatabaseError databaseError) {
}
});
}
public class NotificationViewHolder extends RecyclerView.ViewHolder {
private TextView NotificationUserName;
private Button cancelRequestButton;
private CircleImageView profileImage;
public NotificationViewHolder(#NonNull View itemView) {
super(itemView);
NotificationUserName = itemView.findViewById(R.id.NotificationUserName);
cancelRequestButton = itemView.findViewById(R.id.cancelRequestBtn);
profileImage = itemView.findViewById(R.id.profileImage);
}
}
}
My APP Problems screenshot -
let I have two request
1) if I delete 2nd data 1st data show doubles:
2) if I delete 1st data, 1st data goes into 2nd row and 2nd data came into 1st row:
Replace
removeItem(position);
with
removeItem(holder.getAdapterPosition());
You initialize your recyclerView and adapter in onCreateView which was not appropriate.You have to override the method onViewCreated then initialize your recyclerView and adapter.try like this
public class NotificationFragment extends Fragment {
private RecyclerView NotificationRecyclerView;
private NotificationAdapter adapter;
private List<Friend> friendList;
public NotificationFragment() {
// 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_notification, container, false);
return view;
}
#Override
public void onViewCreated(#NonNull View view, #Nullable Bundle savedInstanceState) {
super.onViewCreated(view, savedInstanceState);
NotificationRecyclerView = view.findViewById(R.id.NotificationRecyclerView);
NotificationRecyclerView.setHasFixedSize(true);
LinearLayoutManager LayoutManager = new LinearLayoutManager(getContext());
NotificationRecyclerView.setLayoutManager(LayoutManager);
friendList = new ArrayList<>();
adapter = new NotificationAdapter(getContext(), friendList);
NotificationRecyclerView.setAdapter(adapter);
readAllNotification();
}
private void readAllNotification() {
final FirebaseUser firebaseUser = FirebaseAuth.getInstance().getCurrentUser();
DatabaseReference reference = FirebaseDatabase.getInstance().getReference("FriendRequest");
reference.addValueEventListener(new ValueEventListener() {
#Override
public void onDataChange(#NonNull DataSnapshot dataSnapshot) {
for (DataSnapshot snapshot : dataSnapshot.getChildren()) {
Friend friend = snapshot.getValue(Friend.class);
if (firebaseUser.getUid().equals(friend.getReceiverID())) {
friendList.add(friend);
}
}
Collections.reverse(friendList);
adapter.notifyDataSetChanged();
}
#Override
public void onCancelled(#NonNull DatabaseError databaseError) {
}
});
}
Ok I just noticed you passed a parameter in removeItem method using holder.getAdapterPosition() which is causing your problem.Try to pass the position which is provided by public void onBindViewHolder(#NonNull final NotificationViewHolder holder, final int position).So the basic error is when you are in onBindViewHolder you don't need to use holder.getAdapterPosition() because onBindViewHolder already giving you the position
In your removeItem method use notifyDataSetChanged instead of notifyItemRemoved(position)
try like this
#Override
public void onBindViewHolder(#NonNull final NotificationViewHolder holder, final int position) {
final Friend friend = friendList.get(position);
holder.cancelRequestButton.setOnClickListener(new View.OnClickListener() {
#Override
public void onClick(View v) {
FirebaseDatabase.getInstance().getReference("FriendRequest").child(friend.getRequestID()).removeValue().addOnCompleteListener(new OnCompleteListener<Void>() {
#Override
public void onComplete(#NonNull Task<Void> task) {
removeItem(position);
Toast.makeText(context, "removed", Toast.LENGTH_SHORT).show();
}
});
}
});
}
public void removeItem(int position) {
friendList.remove(position);
notifyDataSetChanged();
}
Here is my fragment
public class TransactionsFragment extends Fragment {
private FirebaseAuth mAuth;
private DatabaseReference mDBref;
FirebaseUser Fuser;
private String UID;
private RecyclerView recyclerView;
private RecyclerView.Adapter trpAdapter;
private List<TransGetterSetter> DataList;
String trans_id;
#Override
public View onCreateView(LayoutInflater inflater, ViewGroup container,
Bundle savedInstanceState) {
// Inflate the layout for this fragment
View v = inflater.inflate(R.layout.fragment_transactions, container, false);
DataList = new ArrayList<>();
recyclerView = (RecyclerView) v.findViewById(R.id.RVList);
recyclerView.setLayoutManager(new LinearLayoutManager(getContext()));
TransactionRVAdapter trvAdapter = new TransactionRVAdapter(DataList, getContext());
recyclerView.setAdapter(trvAdapter);
mAuth = FirebaseAuth.getInstance();
mDBref = FirebaseDatabase.getInstance().getReference();
Fuser = mAuth.getInstance().getCurrentUser();
UID = Fuser.getUid();
mDBref.child("transactions").child(UID).addValueEventListener(new ValueEventListener() {
#Override
public void onDataChange(#NonNull DataSnapshot dataSnapshot) {
for (DataSnapshot chidSnap : dataSnapshot.getChildren()) {
trans_id = chidSnap.getKey();
DataList.add(new TransGetterSetter("" + trans_id));
}
}
#Override
public void onCancelled(#NonNull DatabaseError databaseError) {
}
});
trvAdapter.notifyDataSetChanged();
return v;
}
}
If i toast "trans_id" string im getting expected result.
Here is My Adapter class
public class TransactionRVAdapter extends RecyclerView.Adapter<TransactionRVAdapter.rvViewHolder> {
Context mContext;
List<TransGetterSetter> DataList = new ArrayList<>();
public class rvViewHolder extends RecyclerView.ViewHolder{
private TextView TransId;
public rvViewHolder(#NonNull View itemView) {
super(itemView);
TransId = (TextView) itemView.findViewById(R.id.TransIdTxt);
}
}
public TransactionRVAdapter( List<TransGetterSetter> DataList,Context mContext){
this.DataList = DataList;
this.mContext = mContext;
}
#NonNull
#Override
public rvViewHolder onCreateViewHolder(#NonNull ViewGroup viewGroup, int i) {
LayoutInflater inflater = LayoutInflater.from(mContext);
View view = inflater.inflate(R.layout.fragment_transactions_item, viewGroup, false);
return new rvViewHolder(view);
}
#Override
public void onBindViewHolder(#NonNull rvViewHolder rvViewHolder, int i) {
rvViewHolder.TransId.setText(DataList.get(i).getTrans_id());
}
#Override
public int getItemCount() {
return DataList.size();
}
}
Here is my GetterSetter class
public class TransGetterSetter {
private String trans_id;
public TransGetterSetter() {
}
public TransGetterSetter(String trans_id) {
this.trans_id = trans_id;
}
public String getTrans_id() {
return trans_id;
}
public void setTrans_id(String trans_id) {
this.trans_id = trans_id;
}
}
Im able to get Data from firebase, but when i try to add it to recycler view it dosen't show any data. Recycler view is showing empty. I checked my code many time but haven't found solution.
You should call :
trvAdapter.notifyDataSetChanged();
After the for loop inside the (onDataChange) event listener.
Try to called ..
DataList.add(new TransGetterSetter("" + trans_id));
after this line called ..
trvAdapter.notifyDataSetChanged();
I am trying to load firebase list of data in my custom recycler adapter but I am unable to load it.
this code is displaying data in my logcat but I am unable to load in my app.
logcat showing no errors though. If I use firebase UI and try to do this thing then it is working fine but I want to inset native ads in recycler view to I had to migrate to custom adapter and now I am stuck with this issue. :(
my custom recycler adapet.
public class AuthorNameCustomRecyclerAdapter extends RecyclerView.Adapter<RecyclerView.ViewHolder> {
ArrayList<AuthorsCLA> authorlist;
Context mcontext;
public class NamesHolder extends RecyclerView.ViewHolder {
public TextView name;
public NamesHolder(View itemView) {
super(itemView);
name = (TextView)itemView.findViewById(R.id.authorNameTextView);
}
}
public AuthorNameCustomRecyclerAdapter(ArrayList<AuthorsCLA> authorlist, Context mcontext) {
this.authorlist = authorlist;
this.mcontext = mcontext;
}
#Override
public RecyclerView.ViewHolder onCreateViewHolder(ViewGroup parent, int viewType) {
RecyclerView.ViewHolder viewHolder = null;
LayoutInflater inflater = LayoutInflater.from(parent.getContext());
switch (viewType) {
case 1: {
View view = inflater.inflate(R.layout.author_list_cv, parent, false);
viewHolder = new NamesHolder(view);
break;
}
}
return viewHolder;
}
#Override
public void onBindViewHolder(RecyclerView.ViewHolder holder, int position) {
final AuthorsCLA authorsModel = authorlist.get(holder.getAdapterPosition());
switch (holder.getItemViewType()){
case 1:{
NamesHolder nameHolder = (NamesHolder) holder;
nameHolder.name.setText(authorsModel.getAuthorname());
nameHolder.name.setOnClickListener(new View.OnClickListener() {
#Override
public void onClick(View view) {
Intent intent = new Intent(view.getContext(), AuthorQuotesDetailActvity.class);
mcontext.startActivity(intent);
}
});
}
}
}
#Override
public int getItemCount() {
return authorlist.size();
}
}
here is the class where i am calling custom recycler adapter.
public class AuthorsList extends AppCompatActivity {
private RecyclerView recyclerViewAuthor;
private StaggeredGridLayoutManager mlayoutManager;
private GridLayoutManager manager;
FirebaseDatabase database = FirebaseDatabase.getInstance();
DatabaseReference mdatabaseReference = database.getReference();
private AdView mAdView;
private RecyclerView.Adapter adapter;
private ArrayList<AuthorsCLA> authorlist;
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.authors_list);
MobileAds.initialize(this, "ca-app-pub-7854400750152181~4721849113");
mAdView = (AdView) findViewById(R.id.adView1);
AdRequest adRequest = new AdRequest.Builder().addTestDevice("2A79E20CADE70C60CF36B2E8EE9103FF").build();
mAdView.loadAd(adRequest);
recyclerViewAuthor = (RecyclerView) findViewById(R.id.authorsRecyclerView);
DatabaseReference mListItemRef = mdatabaseReference.child("en/of");
authorlist = new ArrayList<>();
manager = new GridLayoutManager(this,2);
recyclerViewAuthor.setLayoutManager(manager);
ChildEventListener childEventListener = new ChildEventListener() {
#Override
public void onChildAdded(DataSnapshot dataSnapshot, String s) {
Log.d("Added",dataSnapshot.getKey());
fetchData(dataSnapshot);
}
#Override
public void onChildChanged(DataSnapshot dataSnapshot, String s) {
}
#Override
public void onChildRemoved(DataSnapshot dataSnapshot) {
}
#Override
public void onChildMoved(DataSnapshot dataSnapshot, String s) {
}
#Override
public void onCancelled(DatabaseError databaseError) {
}
};
mListItemRef.addChildEventListener(childEventListener);
adapter = new AuthorNameCustomRecyclerAdapter(authorlist, this);
recyclerViewAuthor.setAdapter(adapter);
}
private void fetchData(DataSnapshot dataSnapshot) {
AuthorsCLA listItem=dataSnapshot.getValue(AuthorsCLA.class);
authorlist.add(listItem);
// recyclerViewAuthor.setAdapter(adapter);
}
}
onChildAdded() will be called each time when the child is fetched by firebase call. This is asynchronous process.
In your code you are adding it into ArrayList<>, but somehow you are not notifying the adapter that child is being added. It is safe to do that in your
private void fetchData(DataSnapshot dataSnapshot) {
AuthorsCLA listItem = dataSnapshot.getValue(AuthorsCLA.class);
authorlist.add(listItem);
adapter.notifyItemInserted(authorlist.size() - 1); // Notify the adapter
}
I'll appreciate if anyone can help me with this.
So what's happening is the Adapter is being declared before the SenderNames Array List is fetched from Firebase Database.So how do I wait for the SenderNames to be fetched first from database and then display them?
Tab 2 code
public class Tab2 extends Fragment {
private static RecyclerView.Adapter adapter;
private RecyclerView.LayoutManager layoutManager;
private static RecyclerView recyclerView;
private static ArrayList<String> reminderMessages;
protected static ArrayList<String> senderNames;
String receiverUID;
private DatabaseReference mDatabase;
int i =0;
private Button profile;
//Overriden method onCreateView
#Override
public View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState) {
//Returning the layout file after inflating
//Change R.layout.tab1 in you classes
View v =inflater.inflate(R.layout.tab2, container, false);
final FirebaseUser user = FirebaseAuth.getInstance().getCurrentUser();
reminderMessages = new ArrayList<>();
receiverUID = user.getUid();
mDatabase = FirebaseDatabase.getInstance().getReference();
Query query = mDatabase.child("reminders").orderByChild("receiverUID").equalTo(receiverUID);
//Setting size of recycler view as constant
recyclerView = (RecyclerView) v.findViewById(R.id.my_recycler_view2);
recyclerView.setHasFixedSize(true);
//Setting Linear Layout
layoutManager = new LinearLayoutManager(getActivity());
recyclerView.setLayoutManager(layoutManager);
recyclerView.setItemAnimator(new DefaultItemAnimator());
query.addValueEventListener(new ValueEventListener() {
#Override
public void onDataChange(DataSnapshot dataSnapshot) {
senderNames = new ArrayList<>();
for (DataSnapshot ds : dataSnapshot.getChildren()) {
//Getting corresponding username of the ReceiverUID
//Getting senderUID
String sUID = ds.child("senderUID").getValue(String.class);
//Getting senders Name
GetSenderName getName = new GetSenderName();
getName.GetSenderssName(sUID);
//Getting message from database
String message = ds.child("reminderMessage").getValue(String.class);
//Adding database to ArrayList
reminderMessages.add(message);
//Getting corresponding username of the ReceiverUID
// Log.d("String names", receiverNames.toString());
}
adapter = new DataAdapter(reminderMessages,senderNames);
recyclerView.setAdapter(adapter);
}
#Override
public void onCancelled(DatabaseError databaseError) {
//Error in Reaching Database
Toast.makeText(getContext(), "Something went Wrong!", Toast.LENGTH_SHORT).show();
}
});
return v;
}
GetSenderName Class
import static com.example.admin.import2.Tab2.senderNames;
public class GetSenderName {private FirebaseAuth auth;
ListView listView;
private DatabaseReference mDatabase;
private String senderName;
public void GetSenderssName(String UID){
mDatabase = FirebaseDatabase.getInstance().getReference().child("users");
//Running a query to find matching UID
Query query = mDatabase.orderByKey().equalTo(UID);
query.addListenerForSingleValueEvent(new ValueEventListener() {
#Override
public void onDataChange(DataSnapshot dataSnapshot2) {
// Getting user name with matching UID
for (DataSnapshot users : dataSnapshot2.getChildren()) {
senderName = users.child("username").getValue(String.class);
senderNames.add(senderName);
Log.d("sendername retrieved",senderNames.toString());
}
}
#Override
public void onCancelled(DatabaseError databaseError) {
}
});
}
}
DataAdapter Class
public class DataAdapter extends RecyclerView.Adapter<DataAdapter.ViewHolder> {
private ArrayList<String> reminderMessage;
private ArrayList<String> receiverName;
public DataAdapter(ArrayList<String> reminderMessage,ArrayList<String> receiverName) {
this.reminderMessage = reminderMessage;
this.receiverName = receiverName;
}
#Override
public DataAdapter.ViewHolder onCreateViewHolder(ViewGroup viewGroup,int i) {
View view = LayoutInflater.from(viewGroup.getContext()).inflate(R.layout.cards_layout, viewGroup, false);
return new ViewHolder(view);
}
#Override
public void onBindViewHolder(DataAdapter.ViewHolder viewHolder, int i) {
viewHolder.reminderText.setText(reminderMessage.get(i));
viewHolder.receiverName.setText(receiverName.get(i));
}
#Override
public int getItemCount() {
return reminderMessage.size();
}
public class ViewHolder extends RecyclerView.ViewHolder{
private TextView reminderText;
private TextView receiverName;
public ViewHolder(View view) {
super(view);
reminderText = (TextView)view.findViewById(R.id.remindertext);
receiverName = (TextView)view.findViewById(R.id.receiverName);
}
}
}
To avoid problems like populate a list before the databases values are fetched, you should use a FirebaseRecyclerAdapter available in firebaseUI library.
It work in asynchronously so you dont need to do nothing. Just set up the recyclerview, the adapter and the query.
Take a look at the official repository
FirebaseUI
Instead of sending the data in constructor you can create some setter method to set the data and update the list,
Remove the arguments in Adapter constructor
Initialize the ArrayList while declaring as a global variable.
Create a setter method to set the data,
If you do your Adapter will be like this,
public class DataAdapter extends RecyclerView.Adapter<DataAdapter.ViewHolder> {
private ArrayList<String> reminderMessage = new ArrayList<>();
private ArrayList<String> receiverName = new ArrayList<>();
public DataAdapter(ArrayList<String> reminderMessage, ArrayList<String> receiverName) {
this.reminderMessage = reminderMessage;
this.receiverName = receiverName;
}
public void setData(ArrayList<String> reminderMessage, ArrayList<String> receiverName) {
if(reminderMessage == null || receiverName != null) {
return;
}
this.reminderMessage.clear();
this.receiverName.clear();
this.reminderMessage.addAll(reminderMessage);
this.receiverName.addAll(receiverName);
notifyDataSetChanged();
}
#Override
public DataAdapter.ViewHolder onCreateViewHolder(ViewGroup viewGroup, int i) {
View view = LayoutInflater.from(viewGroup.getContext()).inflate(R.layout.cards_layout, viewGroup, false);
return new ViewHolder(view);
}
#Override
public void onBindViewHolder(DataAdapter.ViewHolder viewHolder, int i) {
viewHolder.reminderText.setText(reminderMessage.get(i));
viewHolder.receiverName.setText(receiverName.get(i));
}
#Override
public int getItemCount() {
return reminderMessage.size();
}
public class ViewHolder extends RecyclerView.ViewHolder {
private TextView reminderText;
private TextView receiverName;
public ViewHolder(View view) {
super(view);
reminderText = (TextView) view.findViewById(R.id.remindertext);
receiverName = (TextView) view.findViewById(R.id.receiverName);
}
}
}
so from your activity you can call like this, adapter.setData(reminderMessages,senderNames); so that you can create the adapter and set in Recycle View before get the data from server.