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Deletion of Node is not working in Firebase Realtime Database in Android Java

I am making an application in which products are inserted into the database and I am inserting the 1 product once. it is working fine. But when I delete a specific node/ product from Database. deletion code is also working fine but at the same time product is again adding into the database.
Main Fragment Code;
public class Products_fragment extends Fragment {
FloatingActionButton fab_addproduct;
RecyclerView recyclerView;
EditText searchview;
BottomSheetDialog bottomSheetDialog;
FirebaseDatabase firebaseDatabase;
ArrayList<Product_model> DatabaseProductlist;
FirebaseAuth auth;
CircularDotsLoader ProgressBar;
#Override
public View onCreateView(LayoutInflater inflater, ViewGroup container,
Bundle savedInstanceState) {
View view = inflater.inflate(R.layout.fragment_products_fragment, container, false);
setviews(view);
setInitilization();
setclicks();
setadapter();
return view;
}
private void setInitilization() {
DatabaseProductlist = new ArrayList<>();
}
private void setadapter() {
FirebaseDatabase database = FirebaseDatabase.getInstance();
FirebaseUser currentFirebaseUser = FirebaseAuth.getInstance().getCurrentUser();
assert currentFirebaseUser != null;
String UID = currentFirebaseUser.getUid();
DatabaseReference reference = database.getReference("Users").child(UID).child("Products");
reference.addListenerForSingleValueEvent(new ValueEventListener() {
#SuppressLint("NotifyDataSetChanged")
#Override
public void onDataChange(#NonNull DataSnapshot snapshot) {
ProgressBar.setVisibility(View.GONE);
DatabaseProductlist.clear();
for (DataSnapshot dataSnapshot : snapshot.getChildren()) {
Product_model model = dataSnapshot.getValue(Product_model.class);
DatabaseProductlist.add(model);
}
Product_Adapter product_adapter = new Product_Adapter(DatabaseProductlist);
recyclerView.setAdapter(product_adapter);
product_adapter.notifyDataSetChanged();
}
#Override
public void onCancelled(#NonNull DatabaseError error) {
ToastUtility.showErrorToast(getContext(), error.getMessage());
}
});
}
private void setclicks() {
fab_addproduct.setOnClickListener(new View.OnClickListener() {
#Override
public void onClick(View view) {
bottomSheetDialog = new BottomSheetDialog(getContext(), R.style.AppBottomSheetDialogTheme);
bottomSheetDialog.setContentView(R.layout.productadd_bottom_sheet);
TextInputEditText product_id = bottomSheetDialog.findViewById(R.id.product_id);
TextInputEditText product_name = bottomSheetDialog.findViewById(R.id.product_name);
TextInputEditText product_quantity = bottomSheetDialog.findViewById(R.id.product_quantity);
MaterialButton add_btn = bottomSheetDialog.findViewById(R.id.add_btn);
TextInputEditText product_price = bottomSheetDialog.findViewById(R.id.product_price);
add_btn.setOnClickListener(new View.OnClickListener() {
#Override
public void onClick(View view) {
if (Objects.requireNonNull(product_name.getText()).toString().isEmpty() || product_id.getText().toString().isEmpty() || product_price.getText().toString().isEmpty() || product_quantity.getText().toString().isEmpty()) {
ToastUtility.showErrorToast(getContext(), "Please Fill all Fields");
} else {
Product_model model = new Product_model(Integer.parseInt(product_id.getText().toString()), Integer.parseInt(product_quantity.getText().toString()), Integer.parseInt(product_price.getText().toString()), product_name.getText().toString());
firebaseDatabase = FirebaseDatabase.getInstance();
DatabaseReference reference = firebaseDatabase.getReference("Users");
FirebaseUser currentFirebaseUser = FirebaseAuth.getInstance().getCurrentUser();
assert currentFirebaseUser != null;
String UID = currentFirebaseUser.getUid();
reference.child(UID).child("Products").addListenerForSingleValueEvent(new ValueEventListener() {
#Override
public void onDataChange(#NonNull DataSnapshot snapshot) {
if (snapshot.child(product_name.getText().toString().trim()).exists()) {
ToastUtility.showErrorToast(getContext(),"Product Already Exists!");
}
else{
reference.child(UID).child("Products").child(product_name.getText().toString().trim()).setValue(model).addOnCompleteListener(new OnCompleteListener<Void>() {
#Override
public void onComplete(#NonNull Task<Void> task) {
if(task.isSuccessful()){
ToastUtility.showSuccessToast(getContext(),"Successfully Added");
setadapter();
}
else{
ToastUtility.showErrorToast(getContext(), Objects.requireNonNull(task.getException()).getMessage());
}
}
});
}
}
#Override
public void onCancelled(#NonNull DatabaseError error) {
ToastUtility.showErrorToast(getContext(),error.getMessage());
}
});
}
}
});
bottomSheetDialog.show();
}
});
}
private void setviews(View view) {
recyclerView = view.findViewById(R.id.recyclerView);
fab_addproduct = view.findViewById(R.id.fab_addproduct);
searchview = view.findViewById(R.id.searchview);
ProgressBar = view.findViewById(R.id.progressbar);
}
}
Adapter Code:
public class Product_Adapter extends RecyclerView.Adapter<Product_Adapter.myviewholder> {
ArrayList<Product_model> dataholder;
public Product_Adapter(ArrayList<Product_model> dataholder) {
this.dataholder = dataholder;
}
#NonNull
#Override
public myviewholder onCreateViewHolder(#NonNull ViewGroup parent, int viewType) {
View view = LayoutInflater.from(parent.getContext()).inflate(R.layout.singlerow_product, parent, false);
return new myviewholder(view); }
#SuppressLint("SetTextI18n")
#Override
public void onBindViewHolder(#NonNull myviewholder holder, int position) {
holder.idtv.setText("" + dataholder.get(position).getId());
holder.pnametv.setText("" + dataholder.get(position).getProduct_name());
holder.pqtytv.setText("" + dataholder.get(position).getProduct_quantity());
holder.ppritv.setText("" + dataholder.get(position).getProduct_price());
holder.delimg.setOnClickListener(new View.OnClickListener() {
#Override
public void onClick(View view) {
FirebaseDatabase db = FirebaseDatabase.getInstance();
FirebaseUser curUser = FirebaseAuth.getInstance().getCurrentUser();
assert curUser != null;
String UID = curUser.getUid();
String productname = dataholder.get(holder.getAdapterPosition()).getProduct_name();
DatabaseReference reference = db.getReference("Users").child(UID).child("Products");
reference.child(productname).setValue(null).addOnCompleteListener(new OnCompleteListener<Void>() {
#Override
public void onComplete(#NonNull Task<Void> task) {
if(task.isSuccessful())
{
ToastUtility.showSuccessToast(view.getContext(),"Suucessfully Deleted");
notifyItemRemoved(holder.getAdapterPosition());
}
else
{
ToastUtility.showErrorToast(view.getContext(),"Product is not deleting ");
}
}
});
}
});
}
#Override
public int getItemCount() {
return dataholder.size();
}
static class myviewholder extends RecyclerView.ViewHolder{
TextView idtv, pnametv, pqtytv, ppritv, delimg, edit_img;
public myviewholder(#NonNull View itemView) {
super(itemView);
idtv = itemView.findViewById(R.id.idtv);
pnametv = itemView.findViewById(R.id.pnametv);
pqtytv = itemView.findViewById(R.id.pqtytv);
ppritv = itemView.findViewById(R.id.ppritv);
delimg = itemView.findViewById(R.id.delimg);
edit_img = itemView.findViewById(R.id.edit_img);
}
}
}

When you click delete, shouldn't you remove your item from the list before notifying data changed:
//this code belongs to the part where you click the delete
.........
reference.child(productname).setValue(null).addOnCompleteListener(new OnCompleteListener<Void>() {
#Override
public void onComplete(#NonNull Task<Void> task) {
if(task.isSuccessful())
{
ToastUtility.showSuccessToast(view.getContext(),"Suucessfully Deleted");
//here remove the item from your list
dataholder.remove(holder.getAdapterPosition());
//then notify the adapter
notifyItemRemoved(holder.getAdapterPosition());
}

Populate list before calling method Java

I am creating a social app and as soon as the user opens the app, they are suppose to see random posts that I load from the database.
But I don't see that and I have to click on the Random tab to see the posts. So my guess is that the list isn't populated with data by the time the method readRandPosts(); gets called. It's not showing up as null so I have no clue what's wrong. I've checked multiple answers on here and still found nothing to solve my problem. Can someone please help me see what I'm doing wrong ?
private RecyclerView recyclerView;
private PostAdapter postAdapter;
private List<Post> postLists;
#Override
public View onCreateView(LayoutInflater inflater, ViewGroup container,
Bundle savedInstanceState) {
View view = inflater.inflate(R.layout.fragment_home, container, false);
HomeFragment homeFragment = new HomeFragment();
homeFragment.post = post;
//////////////////////////// recycler view //////////////////////////////
recyclerView = (VideoPlayerRecyclerView) view.findViewById(R.id.recyclerview);
LinearLayoutManager layoutManager = new LinearLayoutManager(getContext(), LinearLayoutManager.VERTICAL, false);
//layoutManager.setOrientation(RecyclerView.VERTICAL);
recyclerView.setLayoutManager(layoutManager);
recyclerView.setAdapter(postAdapter);
layoutManager.setReverseLayout(false);
layoutManager.setStackFromEnd(false);
VerticalSpacingItemDecorator itemDecorator = new VerticalSpacingItemDecorator(0);
recyclerView.addItemDecoration(itemDecorator);
postLists = new ArrayList<>();
//postLists.clear();
postAdapter = new PostAdapter(getContext(), postLists);
recyclerView.setAdapter(postAdapter);
progressBar = view.findViewById(R.id.progress_circular);
followingBtn = view.findViewById(R.id.followingBtn);
randomBtn = view.findViewById(R.id.randomBtn);
followingBtn.setOnClickListener(new View.OnClickListener() {
#Override
public void onClick(View view) {
checkFollowing();
Toast.makeText(getContext(), "Following", Toast.LENGTH_SHORT).show();
}
});
randomBtn.setOnClickListener(new View.OnClickListener() {
#Override
public void onClick(View view) {
readRandPosts();
//Toast.makeText(getContext(), "Random", Toast.LENGTH_SHORT).show();
}
});
readRandPosts();
if (postLists != null) {
//Toast.makeText(getContext(), "not null.", Toast.LENGTH_SHORT).show();
} else {
Toast.makeText(getContext(), "Posts are null.", Toast.LENGTH_SHORT).show();
}
return view;
}
private void readRandPosts() {
DatabaseReference reference = FirebaseDatabase.getInstance().getReference("Video_Posts");
FirebaseUser user = FirebaseAuth.getInstance().getCurrentUser();
reference.addValueEventListener(new ValueEventListener() {
#Override
public void onDataChange(#NonNull DataSnapshot dataSnapshot) {
postLists.clear();
for (DataSnapshot snapshot:dataSnapshot.getChildren()) {
Post post = snapshot.getValue(Post.class);
assert post != null;
if (user != null ) {
DatabaseReference dbref = FirebaseDatabase.getInstance().getReference("Follow")
.child(post.getPublisher())
.child("followers")
.child(FirebaseAuth.getInstance().getCurrentUser().getUid());
dbref.addValueEventListener(new ValueEventListener() {
#Override
public void onDataChange(#NonNull DataSnapshot dataSnapshot) {
if (!dataSnapshot.exists()) {
postLists.add(post);
//Collections.shuffle(postLists);
} else {
//postLists.add(post);
Toast.makeText(getContext(), "Nothing to show.", Toast.LENGTH_SHORT).show();
}
}
#Override
public void onCancelled(#NonNull DatabaseError error) {
}
});
} else {
Toast.makeText(getContext(), "User null.", Toast.LENGTH_SHORT).show();
}
}
if(postLists == null ) {
progressBar.setVisibility(View.GONE);
Toast.makeText(getContext(), "No data", Toast.LENGTH_SHORT).show();
}
//Collections.reverse(postLists);
postAdapter.notifyDataSetChanged();
progressBar.setVisibility(View.GONE);
}
#Override
public void onCancelled(#NonNull DatabaseError error) {
}
});
}

It's not showing up as null because you are assigning a new ArrayList to the variable here:
postLists = new ArrayList<>();
So instead of checking for null, you should be checking if the list is empty.

How do I get the Uid of the current user and of other users from firebase realtime database

I had user shared preferences to get the current Uid or other Uid from realtime database. But I need to do the same without the use of shared preferences. This is for my ProfileActivity and I am using viewpager with three different fragments. The shared preferences show only the current user's profile even when searched for other user in the app.
The image attached is the output of the profile activity in my smartphone. The top bar containing the username and the logout button is of the profile activity and the rest below the blue banner is of the viewpager
public class ProfileActivity extends AppCompatActivity {
private ImageView logout;
private TextView post;
private FloatingActionButton floatingActionButton;
private TabLayout tabLayout;
private ViewPager viewPager;
private TextView username;
private FirebaseUser fUser;
private DatabaseReference databaseReference;
private FirebaseDatabase firebaseDatabase;
private FirebaseAuth firebaseAuth;
String profileId;
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_profile);
fUser = FirebaseAuth.getInstance().getCurrentUser();
firebaseAuth = FirebaseAuth.getInstance();
databaseReference = FirebaseDatabase.getInstance().getReference()
.child("Users").child(Objects.requireNonNull(firebaseAuth.getUid()));
String data = getBaseContext().getSharedPreferences("PROFILE", Context.MODE_PRIVATE)
.getString("profileId", "none");
if (data.equals("none")){
profileId = fUser.getUid();
} else{
profileId = data;
}
logout = findViewById(R.id.log_out);
username = findViewById(R.id.username);
floatingActionButton = findViewById(R.id.floatingActionButton);
post = findViewById(R.id.posts_account);
tabLayout = findViewById(R.id.tab_layout);
viewPager = findViewById(R.id.view_pager);
tabLayout.setupWithViewPager(viewPager);
VPAdapter vpAdapter = new VPAdapter(getSupportFragmentManager(), FragmentPagerAdapter.BEHAVIOR_RESUME_ONLY_CURRENT_FRAGMENT);
vpAdapter.addFragment(new Profile(), "Profile");
vpAdapter.addFragment(new MyPosts(), "Posts");
if (profileId.equals(fUser.getUid())){
vpAdapter.addFragment(new SavedPosts(), "Saved");
}
viewPager.setAdapter(vpAdapter);
getPostCount();
userInfo();
getSupportActionBar().hide();
floatingActionButton.setOnClickListener(new View.OnClickListener() {
#Override
public void onClick(View v) {
startActivity(new Intent(ProfileActivity.this, PostActivity.class));
finish();
}
});
logout.setOnClickListener(new View.OnClickListener() {
#Override
public void onClick(View v) {
AlertDialog alertDialog = new AlertDialog.Builder(ProfileActivity.this).create();
alertDialog.setTitle("Are you sure to logout?");
alertDialog.setButton(AlertDialog.BUTTON_NEGATIVE, "No", new DialogInterface.OnClickListener() {
#Override
public void onClick(DialogInterface dialog, int which) {
dialog.dismiss();
}
});
alertDialog.setButton(AlertDialog.BUTTON_POSITIVE, "Yes", new DialogInterface.OnClickListener() {
#Override
public void onClick(DialogInterface dialog, int which) {
FirebaseAuth.getInstance().signOut();
startActivity(new Intent(ProfileActivity.this, StartActivity.class).setFlags(Intent.FLAG_ACTIVITY_CLEAR_TASK));
finish();
}
});
alertDialog.show();
alertDialog.getButton(AlertDialog.BUTTON_NEGATIVE)
.setTextColor(ContextCompat.getColor(ProfileActivity.this, R.color.colorRed));
alertDialog.getButton(AlertDialog.BUTTON_POSITIVE)
.setTextColor(ContextCompat.getColor(ProfileActivity.this, R.color.colorRed));
}
});
}
private void getPostCount() {
FirebaseDatabase.getInstance().getReference().child("Posts").addValueEventListener(new ValueEventListener() {
#Override
public void onDataChange(#NonNull DataSnapshot dataSnapshot) {
int counter = 0;
for (DataSnapshot snapshot : dataSnapshot.getChildren()){
Posts posts = snapshot.getValue(Posts.class);
if (posts.getPublisher().equals(profileId)) counter ++;
}
post.setText(String.valueOf(counter));
}
#Override
public void onCancelled(#NonNull DatabaseError error) {
}
});
}
private void userInfo() {
FirebaseDatabase.getInstance().getReference().child("Users").child(profileId).addValueEventListener(new ValueEventListener() {
#Override
public void onDataChange(#NonNull DataSnapshot snapshot) {
User user = snapshot.getValue(User.class);
username.setText("#" + user.getUsername());
}
#Override
public void onCancelled(#NonNull DatabaseError error) {
}
});
}
}
The above is the code of the profile activity
public class MyPosts extends Fragment {
private RecyclerView recyclerView;
private PostAdapter photoAdapter;
private List<Posts> myPhotoList;
private FirebaseUser fUser;
String profileId;
#Override
public View onCreateView(LayoutInflater inflater, ViewGroup container,
Bundle savedInstanceState) {
// Inflate the layout for this fragment
View view = inflater.inflate(R.layout.fragment_my_thoughts, container, false);
fUser = FirebaseAuth.getInstance().getCurrentUser();
String data = getContext().getSharedPreferences("PROFILE", Context.MODE_PRIVATE)
.getString("profileId", "none");
if (data.equals("none")){
profileId = fUser.getUid();
} else{
profileId = data;
}
recyclerView = view.findViewById(R.id.recycler_view_pictures);
recyclerView.setHasFixedSize(true);
recyclerView.setLayoutManager(new GridLayoutManager(getContext(), 1));
myPhotoList = new ArrayList<>();
photoAdapter = new PostAdapter(getContext(), myPhotoList);
recyclerView.setAdapter(photoAdapter);
myPhotos();
return view;
}
private void myPhotos() {
FirebaseDatabase.getInstance().getReference().child("Posts").addValueEventListener(new ValueEventListener() {
#Override
public void onDataChange(#NonNull DataSnapshot dataSnapshot) {
myPhotoList.clear();
for (DataSnapshot snapshot : dataSnapshot.getChildren()){
Posts post = snapshot.getValue(Posts.class);
if (post.getPublisher().equals(profileId)){
myPhotoList.add(post);
}
}
Collections.reverse(myPhotoList);
photoAdapter.notifyDataSetChanged();
}
#Override
public void onCancelled(#NonNull DatabaseError error) {
}
});
}
}
the above is the code for the posts fragments inside the viewpager of the profile activity
public class Profile extends Fragment {
private CircleImageView imageProfile;
private TextView followers;
private TextView following;
private TextView fullname;
private TextView bio;
private CircleImageView verification;
private TextView usernamebottom;
private Button editProfile;
private FirebaseUser fUser;
String profileId;
#Override
public View onCreateView(LayoutInflater inflater, ViewGroup container,
Bundle savedInstanceState) {
// Inflate the layout for this fragment
View view = inflater.inflate(R.layout.fragment_profile, container, false);
fUser = FirebaseAuth.getInstance().getCurrentUser();
String data = getContext().getSharedPreferences("PROFILE", Context.MODE_PRIVATE)
.getString("profileId", "none");
if (data.equals("none")){
profileId = fUser.getUid();
} else{
profileId = data;
getContext().getSharedPreferences("PROFILE", Context.MODE_PRIVATE).edit().clear().apply();
}
imageProfile = view.findViewById(R.id.image_profile);
verification = view.findViewById(R.id.verification_profile);
followers = view.findViewById(R.id.followers);
following = view.findViewById(R.id.following);
fullname = view.findViewById(R.id.full_name);
bio = view.findViewById(R.id.bio);
usernamebottom = view.findViewById(R.id.username_btm);
editProfile = view.findViewById(R.id.edit_profile);
getFollowersAndFollowingCount();
userInfo();
if (profileId.equals(fUser.getUid())){
editProfile.setText("Edit profile");
} else {
checkFollowingStatus();
}
editProfile.setOnClickListener(new View.OnClickListener() {
#Override
public void onClick(View v) {
String btnText = editProfile.getText().toString();
if (btnText.equals("Edit profile")){
//Go to edit profile
startActivity(new Intent(getContext(), EditProfileActivity.class));
} else{
if (btnText.equals("follow")){
FirebaseDatabase.getInstance().getReference().child("Follow").child(fUser.getUid())
.child("following").child(profileId).setValue(true);
FirebaseDatabase.getInstance().getReference().child("Follow")
.child(profileId).child("followers").child(fUser.getUid()).setValue(true);
} else {
FirebaseDatabase.getInstance().getReference().child("Follow").child(fUser.getUid())
.child("following").child(profileId).removeValue();
FirebaseDatabase.getInstance().getReference().child("Follow")
.child(profileId).child("followers").child(fUser.getUid()).removeValue();
}
}
}
});
return view;
}
private void checkFollowingStatus() {
FirebaseDatabase.getInstance().getReference().child("Follow").child(fUser.getUid()).child("following")
.addValueEventListener(new ValueEventListener() {
#Override
public void onDataChange(#NonNull DataSnapshot dataSnapshot) {
if (dataSnapshot.child(profileId).exists()) {
editProfile.setText("following");
} else {
editProfile.setText("follow");
}
}
#Override
public void onCancelled(#NonNull DatabaseError error) {
}
});
}
private void getFollowersAndFollowingCount() {
DatabaseReference ref = FirebaseDatabase.getInstance().getReference().child("Follow").child(profileId);
ref.child("followers").addValueEventListener(new ValueEventListener() {
#Override
public void onDataChange(#NonNull DataSnapshot dataSnapshot) {
followers.setText("" + dataSnapshot.getChildrenCount());
}
#Override
public void onCancelled(#NonNull DatabaseError error) {
}
});
ref.child("following").addValueEventListener(new ValueEventListener() {
#Override
public void onDataChange(#NonNull DataSnapshot dataSnapshot) {
following.setText("" + dataSnapshot.getChildrenCount());
}
#Override
public void onCancelled(#NonNull DatabaseError error) {
}
});
}
private void userInfo() {
FirebaseDatabase.getInstance().getReference().child("Users").child(profileId).addValueEventListener(new ValueEventListener() {
#SuppressLint("SetTextI18n")
#Override
public void onDataChange(#NonNull DataSnapshot snapshot) {
User user = snapshot.getValue(User.class);
if (user.getImageurl().equals("default")){
imageProfile.setImageResource(R.drawable.ic_empty_profile);
} else {
Picasso.get().load(user.getImageurl()).into(imageProfile);
}
usernamebottom.setText("#" + user.getUsername());
fullname.setText(user.getName());
bio.setText(user.getBio());
}
#Override
public void onCancelled(#NonNull DatabaseError error) {
}
});
}
}
The above is the code of the user detail fragment also in the view pager of my profile activity

My activity goes to previous activity when firebase database change is detected

Thats the Fragment containing the recyclerView which leads to activity with Chat
public class FragmentBusinessHome extends Fragment {
/* For to do adapter */
private List<String> namesToDo;
private List<String> uids;
private List<String> servicesNames;
private AdapterToDo adapterToDo;
private RecyclerView toDoRecyclerView;
/* For checking requests adapter */
private List<String> userUids;
private List<String> serviceNames;
private List<String> userNames;
private AdapterPendingRequests adapterPendingRequests;
private RecyclerView pendingRequestsRecyclerView;
private FirebaseAuth mAuth;
public FragmentBusinessHome(){
}
#Nullable
#Override
public View onCreateView(#NonNull LayoutInflater inflater, #Nullable ViewGroup container, #Nullable Bundle savedInstanceState) {
View view = inflater.inflate(R.layout.fragment_business_home, container, false);
mAuth = FirebaseAuth.getInstance();
namesToDo = new ArrayList<>();
uids = new ArrayList<>();
servicesNames = new ArrayList<>();
userUids = new ArrayList<>();
serviceNames = new ArrayList<>();
userNames = new ArrayList<>();
toDoRecyclerView = view.findViewById(R.id.toDoRecyclerView);
pendingRequestsRecyclerView = view.findViewById(R.id.requestsToApproveRecyclerView);
LinearLayoutManager layoutManagerActive = new LinearLayoutManager(getActivity());
layoutManagerActive.setStackFromEnd(true);
layoutManagerActive.setReverseLayout(true);
toDoRecyclerView.setLayoutManager(layoutManagerActive);
LinearLayoutManager layoutManagerPendingRequests = new LinearLayoutManager(getActivity());
layoutManagerPendingRequests.setStackFromEnd(true);
layoutManagerPendingRequests.setReverseLayout(true);
pendingRequestsRecyclerView.setLayoutManager(layoutManagerPendingRequests);
String uid = FirebaseAuth.getInstance().getCurrentUser().getUid();
DatabaseReference checkRequests = FirebaseDatabase.getInstance().getReference("Providers").child(uid).child("Gigs");
checkRequests.addListenerForSingleValueEvent(new ValueEventListener() {
#Override
public void onDataChange(#NonNull DataSnapshot dataSnapshot) {
for (DataSnapshot ds : dataSnapshot.getChildren()) {
if (ds.getValue(String.class).equals("active")) {
DatabaseReference getRequests = FirebaseDatabase.getInstance().getReference("Services").child(ds.getKey()).child(uid).child("Gigs").child("pending");
getRequests.addValueEventListener(new ValueEventListener() {
#Override
public void onDataChange(#NonNull DataSnapshot dataSnapshot) {
serviceNames.clear(); userNames.clear(); userUids.clear();
for (DataSnapshot data : dataSnapshot.getChildren()) {
String userName = data.child("names").getValue(String.class);
String serviceName = ds.getKey();
String userUid = data.getKey();
userNames.add(userName);
serviceNames.add(serviceName);
userUids.add(userUid);
adapterPendingRequests = new AdapterPendingRequests(getActivity(), userUids, userNames, serviceNames, mAuth.getCurrentUser().getUid());
adapterPendingRequests.notifyDataSetChanged();
pendingRequestsRecyclerView.setAdapter(adapterPendingRequests);
}
}
#Override
public void onCancelled(#NonNull DatabaseError databaseError) {
}
});
DatabaseReference getActive = FirebaseDatabase.getInstance().getReference("Services").child(ds.getKey()).child(uid).child("Gigs").child("active");
getActive.addValueEventListener(new ValueEventListener() {
#Override
public void onDataChange(#NonNull DataSnapshot dataSnapshot) {
userUids.clear(); namesToDo.clear(); servicesNames.clear();
for(DataSnapshot datas : dataSnapshot.getChildren()){
String userUid = datas.getKey();
String userName = datas.child("names").getValue(String.class);
String serviceName = ds.getKey();
userUids.add(userUid);
namesToDo.add(userName);
servicesNames.add(serviceName);
Log.d("TAG", userUids.toString());
adapterToDo = new AdapterToDo(getActivity(), namesToDo, userUids, servicesNames);
adapterToDo.notifyDataSetChanged();
toDoRecyclerView.setAdapter(adapterToDo);
if(!userUids.isEmpty()){
LinearLayout toDoLayout = view.findViewById(R.id.toDoLayout);
toDoLayout.setVisibility(View.VISIBLE);
}
}
}
#Override
public void onCancelled(#NonNull DatabaseError databaseError) {
}
});
}
}
}
#Override
public void onCancelled(#NonNull DatabaseError databaseError) {
}
});
return view;
}
}
Thats fragment's activity
private ImageButton moreBtn, chatsBtn;
private BottomNavigationView bottomNavigationView;
private FirebaseAuth mAuth;
private FirebaseUser mUser;
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_business_home);
getSupportFragmentManager().beginTransaction().replace(R.id.fragmentContainer, new FragmentBusinessHome()).commit();
mAuth = FirebaseAuth.getInstance();
mUser = mAuth.getCurrentUser();
bottomNavigationView = findViewById(R.id.bottomNavigationView);
bottomNavigationView.setOnNavigationItemSelectedListener(navigationListener);
moreBtn = findViewById(R.id.moreBtn);
chatsBtn = findViewById(R.id.chatsBtn);
moreBtn.setOnClickListener(new View.OnClickListener() {
#Override
public void onClick(View v) {
final PopupMenu popup = new PopupMenu(BusinessHomeActivity.this, moreBtn);
popup.getMenuInflater().inflate(R.menu.popup_toolbar_more_menu, popup.getMenu());
popup.show();
popup.setOnMenuItemClickListener(new PopupMenu.OnMenuItemClickListener() {
#Override
public boolean onMenuItemClick(MenuItem item) {
switch (item.getItemId()){
case R.id.sign_out_btn:
mAuth.signOut();
new android.os.Handler().postDelayed(
new Runnable() {
public void run() {
Intent to_login_activity = new Intent(BusinessHomeActivity.this, WelcomeActivity.class);
startActivity(to_login_activity);
finish();
}
}, 1000);
}
return true;
}
});
}
});
chatsBtn.setOnClickListener(new View.OnClickListener() {
#Override
public void onClick(View v) {
Toast.makeText(BusinessHomeActivity.this, "Will be available soon!", Toast.LENGTH_LONG).show();
}
});
}
private BottomNavigationView.OnNavigationItemSelectedListener navigationListener = new BottomNavigationView.OnNavigationItemSelectedListener() {
#Override
public boolean onNavigationItemSelected(#NonNull MenuItem menuItem) {
Fragment selectedFragment = null;
switch (menuItem.getItemId()){
case R.id.home:
selectedFragment = new FragmentBusinessHome();
break;
case R.id.inbox:
selectedFragment = new FragmentInbox();
break;
case R.id.profile:
selectedFragment = new FragmentProfile();
break;
}
getSupportFragmentManager().beginTransaction().replace(R.id.fragmentContainer, selectedFragment).commit();
return true;
}
};
That's the adapter for the fragment
public class AdapterToDo extends RecyclerView.Adapter<AdapterToDo.MyHolder> {
Context context;
List<String> namesToDo;
List<String> uids;
List<String> servicesNames;
public AdapterToDo(Context context, List<String> namesToDo, List<String> uids, List<String> servicesNames) {
this.context = context;
this.namesToDo = namesToDo;
this.uids = uids;
this.servicesNames = servicesNames;
}
#NonNull
#Override
public AdapterToDo.MyHolder onCreateViewHolder(#NonNull ViewGroup parent, int viewType) {
View view = LayoutInflater.from(context).inflate(R.layout.to_do_item, parent, false);
return new AdapterToDo.MyHolder(view);
}
#Override
public void onBindViewHolder(#NonNull final AdapterToDo.MyHolder holder, final int position) {
holder.userNames.setText(namesToDo.get(position));
String currentUid = uids.get(position);
String currentOppositeName = namesToDo.get(position);
holder.itemView.setOnClickListener(new View.OnClickListener() {
#Override
public void onClick(View v) {
Intent to_chat_activity = new Intent(context, ChatActivity.class);
to_chat_activity.putExtra("oppositeUid", currentUid);
to_chat_activity.putExtra("oppositeNames", currentOppositeName);
to_chat_activity.putExtra("class", getClass().getName());
context.startActivity(to_chat_activity);
}
});
}
#Override
public int getItemCount() {
return uids.size();
}
class MyHolder extends RecyclerView.ViewHolder {
private TextView userNames;
private MyHolder(#NonNull View itemView) {
super(itemView);
userNames = itemView.findViewById(R.id.userNames);
}
}
}
That is the Activity where the fragment's adapter leads to
private String oppositeUid, oppositeNames, className;
private TextView oppositeNamesTextView;
private Button sendBtn;
private EditText message;
private FirebaseAuth mAuth;
private RecyclerView recyclerView;
private List<ModelChat> modelChatList;
private AdapterChat chatAdapter;
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_chat);
mAuth = FirebaseAuth.getInstance();
Intent intent = getIntent();
oppositeUid = intent.getStringExtra("oppositeUid");
oppositeNames = intent.getStringExtra("oppositeNames");
className = intent.getStringExtra("class");
Log.d("CLASSNAME", className);
modelChatList = new ArrayList<>();
oppositeNamesTextView = findViewById(R.id.oppositeNames);
sendBtn = findViewById(R.id.sendBtn);
message = findViewById(R.id.message);
recyclerView = findViewById(R.id.chatRecyclerView);
LinearLayoutManager linearLayout = new LinearLayoutManager(this);
linearLayout.setStackFromEnd(true);
recyclerView.setLayoutManager(linearLayout);
oppositeNamesTextView.setText(oppositeNames);
sendBtn.setOnClickListener(new View.OnClickListener() {
#Override
public void onClick(View v) {
final String mMessage = message.getText().toString().trim();
if(!TextUtils.isEmpty(mMessage)){
HashMap<Object, String> hashMap = new HashMap<>();
hashMap.put("sender", mAuth.getCurrentUser().getUid());
hashMap.put("receiver", oppositeUid);
hashMap.put("message", mMessage);
hashMap.put("timestamp", String.valueOf(System.currentTimeMillis()));
if(className.equals("com.example.uploy.AdapterToDo$1")){
DatabaseReference databaseReference = FirebaseDatabase.getInstance().getReference("Providers").child(mAuth.getCurrentUser().getUid()).child("Chats").child(oppositeUid);
databaseReference.push().setValue(hashMap).addOnSuccessListener(new OnSuccessListener<Void>() {
#Override
public void onSuccess(Void aVoid) {
message.setText("");
}
}).addOnFailureListener(new OnFailureListener() {
#Override
public void onFailure(#NonNull Exception e) {
Toast.makeText(ChatActivity.this, "An error occurred!", Toast.LENGTH_SHORT).show();
}
});
DatabaseReference databaseReference1 = FirebaseDatabase.getInstance().getReference("Users").child(oppositeUid).child("Chats").child(mAuth.getCurrentUser().getUid());
databaseReference1.push().setValue(hashMap).addOnSuccessListener(new OnSuccessListener<Void>() {
#Override
public void onSuccess(Void aVoid) {
message.setText("");
}
}).addOnFailureListener(new OnFailureListener() {
#Override
public void onFailure(#NonNull Exception e) {
Toast.makeText(ChatActivity.this, "An error occurred!", Toast.LENGTH_SHORT).show();
}
});
}else{
DatabaseReference databaseReference = FirebaseDatabase.getInstance().getReference("Providers").child(oppositeUid).child("Chats").child(mAuth.getCurrentUser().getUid());
databaseReference.push().setValue(hashMap).addOnSuccessListener(new OnSuccessListener<Void>() {
#Override
public void onSuccess(Void aVoid) {
message.setText("");
}
}).addOnFailureListener(new OnFailureListener() {
#Override
public void onFailure(#NonNull Exception e) {
Toast.makeText(ChatActivity.this, "An error occurred!", Toast.LENGTH_SHORT).show();
}
});
DatabaseReference databaseReference1 = FirebaseDatabase.getInstance().getReference("Users").child(mAuth.getCurrentUser().getUid()).child("Chats").child(oppositeUid);
databaseReference1.push().setValue(hashMap).addOnSuccessListener(new OnSuccessListener<Void>() {
#Override
public void onSuccess(Void aVoid) {
message.setText("");
}
}).addOnFailureListener(new OnFailureListener() {
#Override
public void onFailure(#NonNull Exception e) {
Toast.makeText(ChatActivity.this, "An error occurred!", Toast.LENGTH_SHORT).show();
}
});
}
}
}
});
if(className.equals("com.example.uploy.AdapterToDo$1")){
DatabaseReference databaseReference = FirebaseDatabase.getInstance().getReference("Providers").child(mAuth.getCurrentUser().getUid()).child("Chats").child(oppositeUid);
databaseReference.addValueEventListener(new ValueEventListener() {
#Override
public void onDataChange(#NonNull DataSnapshot dataSnapshot) {
modelChatList.clear();
for(DataSnapshot snapshot : dataSnapshot.getChildren()){
if(snapshot.getKey().equals("details")){
continue;
}
ModelChat modelChat = snapshot.getValue(ModelChat.class);
modelChatList.add(modelChat);
chatAdapter = new AdapterChat(ChatActivity.this, modelChatList);
chatAdapter.notifyDataSetChanged();
recyclerView.setAdapter(chatAdapter);
}
}
#Override
public void onCancelled(#NonNull DatabaseError databaseError) {
}
});
}else{
DatabaseReference databaseReference = FirebaseDatabase.getInstance().getReference("Users").child(mAuth.getCurrentUser().getUid()).child("Chats").child(oppositeUid);
databaseReference.addValueEventListener(new ValueEventListener() {
#Override
public void onDataChange(#NonNull DataSnapshot dataSnapshot) {
modelChatList.clear();
for(DataSnapshot snapshot : dataSnapshot.getChildren()){
if(snapshot.getKey().equals("details")){
continue;
}
ModelChat modelChat = snapshot.getValue(ModelChat.class);
modelChatList.add(modelChat);
chatAdapter = new AdapterChat(ChatActivity.this, modelChatList);
chatAdapter.notifyDataSetChanged();
recyclerView.setAdapter(chatAdapter);
}
}
#Override
public void onCancelled(#NonNull DatabaseError databaseError) {
}
});
}
}
#Override
public void onBackPressed() {
super.onBackPressed();
Log.d("TAG", "PRESSED");
}
The PROBLEM is that when the fragment opens the activity (it contains messages in chat between to users, which are loaded perfectly fine) and the activity detects any change in the chats database reference it stops and loads the previous activity (where the fragment is placed). I wonder what the solution is and I would be glad if you help me.

RecyclerView shows the same item many times in my app

I've created a match system in my Android program that also includes a chat section which has 2 fragments. The first fragment shows your chats, the second one shows your matches by using RecyclerView and UsersAdapter. However, in the second (match) fragment, people who you matched with are shown many times. For example, the same person is seen many times as you can see here.
My code is below.
UserFragment:
public class UsersFragment extends Fragment {
private RecyclerView recyclerView;
private UsersAdapter usersAdapter;
private List<User> mUsers;
FirebaseFirestore usersfragmentstore;
FirebaseAuth readauth;
DocumentReference readref;
#Override
public View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState) {
// Inflate the layout for this fragment
usersfragmentstore = FirebaseFirestore.getInstance();
readauth = FirebaseAuth.getInstance();
View view = inflater.inflate(R.layout.fragment_users, container, false);
readref = usersfragmentstore.collection("users").document(readauth.getCurrentUser().getUid());
recyclerView = view.findViewById(R.id.recycler_view);
recyclerView.setHasFixedSize(true);
recyclerView.setLayoutManager(new LinearLayoutManager(getContext()));
mUsers = new ArrayList<>();
final FirebaseUser firebaseUser = FirebaseAuth.getInstance().getCurrentUser();
DatabaseReference reference = FirebaseDatabase.getInstance().getReference("users");
reference.addValueEventListener(new ValueEventListener() {
#Override
public void onDataChange(#NonNull DataSnapshot dataSnapshot) {
for (DataSnapshot snapshot : dataSnapshot.getChildren()) {
readref.get().addOnCompleteListener(new OnCompleteListener<DocumentSnapshot>() {
#Override
public void onComplete(#NonNull Task<DocumentSnapshot> task) {
DocumentSnapshot shot = task.getResult();
List<String> matchedid2 = new ArrayList<>();
matchedid2 = (List<String>) shot.get("matchlist");
if (matchedid2.contains(snapshot.getKey())) {
User user = snapshot.getValue(User.class);
mUsers.add(user);
usersAdapter = new UsersAdapter(getContext(), mUsers, false);
recyclerView.setAdapter(usersAdapter);
}
}
});
}
}
#Override
public void onCancelled(#NonNull DatabaseError databaseError) {
}
});
return view;
}
}
UserAdapter:
public class UsersAdapter extends RecyclerView.Adapter<UsersAdapter.ViewHolder> {
private Context mContext;
private List<User> mUsers;
private boolean ischat;
String theLastMessage;
public UsersAdapter(Context mContext, List<User> mUsers, boolean ischat) {
this.mUsers = mUsers;
this.mContext = mContext;
this.ischat = ischat;
}
#NonNull
#Override
public ViewHolder onCreateViewHolder(#NonNull ViewGroup parent, int viewType) {
View view = LayoutInflater.from(mContext).inflate(R.layout.user_item_chat, parent, false);
return new UsersAdapter.ViewHolder(view);
}
#Override
public void onBindViewHolder(#NonNull ViewHolder holder, int position) {
User user = mUsers.get(position);
holder.username.setText(user.getName());
if (user.getImageURL().equals("default")) {
holder.profile_image.setImageResource(R.drawable.profilepicture);
} else {
Glide.with(mContext).load(user.getImageURL()).into(holder.profile_image);
}
if (ischat) {
lastMessage(user.getId(), holder.last_msg);
} else {
holder.last_msg.setVisibility(View.GONE);
}
if (ischat) {
if (user.getStatus().equals("online")) {
holder.img_on.setVisibility(View.VISIBLE);
holder.img_off.setVisibility(View.GONE);
} else {
holder.img_on.setVisibility(View.GONE);
holder.img_off.setVisibility(View.VISIBLE);
}
} else {
holder.img_on.setVisibility(View.GONE);
holder.img_off.setVisibility(View.GONE);
}
holder.itemView.setOnClickListener(new View.OnClickListener() {
#Override
public void onClick(View v) {
Intent intent = new Intent(mContext, MessageActivity.class);
intent.putExtra("userid", user.getId());
mContext.startActivity(intent);
}
});
}
#Override
public int getItemCount() {
return mUsers.size();
}
public class ViewHolder extends RecyclerView.ViewHolder {
public TextView username;
public ImageView profile_image;
private ImageView img_on;
private ImageView img_off;
private TextView last_msg;
public ViewHolder(#NonNull View itemView) {
super(itemView);
username = itemView.findViewById(R.id.chatusername);
profile_image = itemView.findViewById(R.id.profile_image);
img_on = itemView.findViewById(R.id.img_on);
img_off = itemView.findViewById(R.id.img_off);
last_msg = itemView.findViewById(R.id.last_msg);
}
}
private void lastMessage(final String userid, final TextView last_msg) {
theLastMessage = "defalut";
final FirebaseUser firebaseUser = FirebaseAuth.getInstance().getCurrentUser();
DatabaseReference reference = FirebaseDatabase.getInstance().getReference("Chats");
reference.addValueEventListener(new ValueEventListener() {
#Override
public void onDataChange(#NonNull DataSnapshot dataSnapshot) {
for (DataSnapshot snapshot : dataSnapshot.getChildren()) {
Chat chat = snapshot.getValue(Chat.class);
if (firebaseUser != null && chat != null) {
if (chat.getReceiver().equals(firebaseUser.getUid()) && chat.getSender().equals(userid) || chat.getReceiver().equals(userid) && chat.getSender().equals(firebaseUser.getUid())) {
theLastMessage = chat.getMessage();
}
}
}
switch (theLastMessage) {
case "default":
last_msg.setText("No message");
break;
default:
last_msg.setText(theLastMessage);
break;
}
theLastMessage = "default";
}
#Override
public void onCancelled(#NonNull DatabaseError databaseError) {
}
});
}
}
What am I missing?

befor adding new data first clear list by mUsers.clear(); as below
public void onDataChange(#NonNull DataSnapshot dataSnapshot) {
for (DataSnapshot snapshot : dataSnapshot.getChildren()) {
readref.get().addOnCompleteListener(new OnCompleteListener<DocumentSnapshot>() {
#Override
public void onComplete(#NonNull Task<DocumentSnapshot> task) {
DocumentSnapshot shot = task.getResult();
List<String> matchedid2 = new ArrayList<>();
matchedid2 = (List<String>) shot.get("matchlist");
if (matchedid2.contains(snapshot.getKey())) {
mUsers.clear();
User user = snapshot.getValue(User.class);
mUsers.add(user);
usersAdapter = new UsersAdapter(getContext(), mUsers, false);
recyclerView.setAdapter(usersAdapter);
}
}
});
}