public class AddPartAdapter extends RecyclerView.Adapter<AddPartAdapter.ViewHolder> {
private  Context mContext;
private  List<User> mUsers;
EventListener listener;
public interface EventListener {
    void AddParticipant(String id);
public void addEventListener(EventListener listener){
    this.listener = listener;
public void removeEventListener(){
    listener = null;
public AddPartAdapter(Context mContext, List<User> mUsers) {
    this.mContext = mContext;
    this.mUsers = mUsers;
@NonNull
@Override
public AddPartAdapter.ViewHolder onCreateViewHolder(@NonNull ViewGroup parent, int viewType) {
    ViewGroup viewGroup = (ViewGroup) LayoutInflater.from(mContext).inflate(R.layout.add_part_item, parent, false);
    return new AddPartAdapter.ViewHolder(viewGroup);
@Override
public void onBindViewHolder(@NonNull AddPartAdapter.ViewHolder holder, int position) {
    final User user = mUsers.get(position);
    holder.username.setText(user.getUsername());
    holder.dt.setText(user.getDt());
    if (user.getImageUrl().equals("default")) {
        holder.dp.setImageResource(R.drawable.user);
    } else {
        Glide.with(mContext).load(user.getImageUrl()).into(holder.dp);
    holder.addpart_btn.setOnClickListener(new View.OnClickListener() {
        @Override
        public void onClick(View v) {
            String Variable = user.getId();//This is the variable that should pass
            //Send call that method and send the variablethat variable to Fragment
            listener.AddParticipant(Variable);
}

public class AddParticipantsFragment extends Fragment implements AddPartAdapter.EventListener {
private RecyclerView recyclerView;
private List<User> mUsers;
DatabaseReference databaseReference;
FirebaseUser firebaseUser;
private List<Chatlist>usersList;
private AddPartAdapter addPartAdapter;
public String groupId;
@Override
public View onCreateView(LayoutInflater inflater, ViewGroup container,
                         Bundle savedInstanceState) {
    // Inflate the layout for this fragment
    View view = inflater.inflate(R.layout.fragment_add_participants, container, false);
    recyclerView = view.findViewById(R.id.recycler_view);
    recyclerView.setHasFixedSize(true);
    recyclerView.setLayoutManager(new LinearLayoutManager(getContext()));
    usersList = new ArrayList<>();
    firebaseUser = FirebaseAuth.getInstance().getCurrentUser();
    databaseReference = FirebaseDatabase.getInstance().getReference("Chatlist").child(firebaseUser.getUid());
    databaseReference.addValueEventListener(new ValueEventListener() {
        @Override
        public void onDataChange(@NonNull DataSnapshot snapshot) {
            usersList.clear();
            for(DataSnapshot snapshot1 : snapshot.getChildren()){
                Chatlist chatlist = snapshot1.getValue(Chatlist.class);
                usersList.add(chatlist);
            chatList();
        @Override
        public void onCancelled(@NonNull DatabaseError error) {
    AddParticipants activity = (AddParticipants) getActivity();
    assert activity != null;
    groupId = activity.getMyData();
    return view;
private void chatList() {
    mUsers = new ArrayList<>();
    databaseReference = FirebaseDatabase.getInstance().getReference("Users");
    databaseReference.addValueEventListener(new ValueEventListener() {
        @Override
        public void onDataChange(@NonNull DataSnapshot snapshot) {
            mUsers.clear();
            for (DataSnapshot snapshot1 : snapshot.getChildren()){
                User user = snapshot1.getValue(User.class);
                for (Chatlist chatlist : usersList){
                    assert user != null;
                    if(user.getId().equals(chatlist.getId())){
                        if(chatlist.getFriends().equals("Messaged")){
                            mUsers.add(user);
                        }if (chatlist.getFriends().equals("Requested")){
                            //DoNothing
                        if(chatlist.getFriends().equals("Blocked")){
                            //Dont do anything
            AddPartAdapter addPartAdapter = new AddPartAdapter(getContext(), mUsers);
            addPartAdapter.addEventListener();//Here inside the bracket what to add.
            recyclerView.setAdapter(addPartAdapter);
        @Override
        public void onCancelled(@NonNull DatabaseError error) {
public void AddParticipant(String id) {
    //And it should initialize this method
    DatabaseReference databaseReference = FirebaseDatabase.getInstance().getReference("Grouplist").child(groupId);
    HashMap<String, String> hashMap1 = new HashMap<>();
    hashMap1.put("id", id);
    hashMap1.put("admin","false");
    databaseReference.setValue(hashMap1);
public void onDestroy() {
    super.onDestroy();
    addPartAdapter.removeEventListener();
}