public class MainActivity extends AppCompatActivity {

    private EditText user;
    private Button login;
    private TextView txt_title;
    private EditText pass;
    FirebaseDatabase firebaseDatabase
    RecyclerView recyclerView;
    DatabaseReference databaseReference;
    FirebaseRecyclerOptions<post> options;
    FirebaseRecyclerAdapter<post,MyRecyclerViewHolder> adapter;
    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        login = (Button) findViewById(R.id.button);
        user= (EditText) findViewById(R.id.editText);
        pass= (EditText) findViewById(R.id.editText2);
        txt_title = (TextView) findViewById(R.id.textView);

        firebaseDatabase = FirebaseDatabase.getInstance();
        databaseReference = firebaseDatabase.getReference("EDMT_FIREBASE");
        login.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                postComment();
            }
        });


        private void postComment() {   // <--- Errore Variable postComment is never used

            String title = login.getText().toString();
            String content = pass.getText().toString();
            post post = new post(title,content)

            databaseReference.push()
                    .setValue(post);
            adapter.notifyDataSetChanged();

            displayComment();
        }

     private void displayComment() {     //<--- Errore Variable displayComment is never used
        options=
                new FirebaseRecyclerOptions.Builder<post>()
                .setQuery(databaseReference,post.class)
                .build()

         FirebaseRecyclerAdapter<post,MyRecyclerViewHolder> adapter=
                 new FirebaseRecyclerAdapter<post, MyRecyclerViewHolder>(options) {
                     @Override
                     protected void onBindViewHolder(@NonNull MyRecyclerViewHolder holder, int position, @NonNull post model) {
                        holder.textView.setText(model.getTitle());
                        //holder.comment.setText(model.getContent());

                     }

                     @NonNull
                     @Override
                     public MyRecyclerViewHolder onCreateViewHolder(@NonNull ViewGroup parent, int viewType) {
                         View itemView = LayoutInflater.from(getBaseContext()).inflate(R.layout.activity_main,false);
                         return new MyRecyclerViewHolder(itemView);
                     }
                 };
        adapter.startListening();
        recyclerView.setAdapter(adapter);
        }
    }
}