How can I autofill edit text from it in the middle?

Question

I am working on a contact manager project for android. In which I want to automatically fill in the final part of the email address in the field during user registration. For example, when a user enters his username, he should automatically give an offer to @ gmail.com or @ outlook.com, etc.

Well, this is a small part of my code.

String[] maindb = {"@gmail.com", "@rediffmail.com", "@hotmail.com", "@outlook.com"};

mail = (AutoCompleteTextView) findViewById(R.id.A1_edt_mail);

ArrayAdapter<String> adpt = new ArrayAdapter<String>(this, R.layout.support_simple_spinner_dropdown_item, maindb);
mail.setAdapter(adpt);

Well, I got this conclusion

But I want that when the user enters his username, this sentence should appear, but it is not.

Well, my question does not duplicate android, how EditText works as autocomplete this question. My problem is different from this.

Thanks in advance.

Answer 1

maindb → TextWatcher .

Edit

,

final ArrayList<String> maindb = new ArrayList<>();
    maindb.add("@gmail.com");
    maindb.add("@rediffmail.com");
    maindb.add("@hotmail.com");
    maindb.add("@outlook.com");
    final ArrayList<String> compare = new ArrayList<>();
    final ArrayAdapter<String> adpt = new ArrayAdapter<String>(MainActivity.this, R.layout.support_simple_spinner_dropdown_item, compare);
    Word.setAdapter(adpt);
    Word.addTextChangedListener(new TextWatcher() {
        @Override
        public void beforeTextChanged(CharSequence s, int start, int count, int after) {
        }

        @Override
        public void onTextChanged(CharSequence s, int start, int before, int count) {
        }

        @Override
        public void afterTextChanged(Editable s) {
            if (s.length() >= 0)
                if (!s.toString().contains("@")) {
                    compare.clear();
                    for (String aMaindb : maindb) {
                        aMaindb = s + aMaindb;
                        compare.add(aMaindb);
                    }
                    adpt.clear();
                    adpt.addAll(compare);
                }
        }
    });

,