TextInputEditText birthdateInput;
DatePickerFragment datePickerFragment;
datePickerFragment = new DatePickerFragment();
birthdateInput = findViewById(R.id.signup_birthdate);
birthdateInput.setOnClickListener(v -> datePickerFragment.show(getSupportFragmentManager(), "date picker"));

        birthdateInput.setOnFocusChangeListener((v, hasFocus) -> { // cambia la view
            if (hasFocus) {
                datePickerFragment.show(getSupportFragmentManager(), "datePicker");
            }
        });

        datePickerFragment.setOnDatePickerFragmentChanged(new DatePickerFragment.DatePickerFragmentListener() {
            @Override
            public void onDatePickerFragmentOkButton(DialogFragment dialog, Calendar date) {
                @SuppressLint("SimpleDateFormat") SimpleDateFormat format = new SimpleDateFormat("dd/MM/yyyy");
                birthdateInput.setText(format.format(date.getTime()));
            }

            @Override
            public void onDatePickerFragmentCancelButton(DialogFragment dialog) {

            }
        });