Alertdialog textcolor change

  AlertDialog.Builder builder = new AlertDialog.Builder(this);
        builder.setTitle(getString(R.string.new_group));
        final FrameLayout input = (FrameLayout) View.inflate(this, R.layout.dialog_profile_name_update, null);
        final EditText editText = (EditText) input.findViewById(R.id.et_rename_profile_name);
        editText.setHint(getString(R.string.hint_name_this_group_chat));
        editText.setText(getString(R.string.label_group));
        editText.setSelection(getString(R.string.label_group).length());
        builder.setView(input);

        builder.setPositiveButton(getString(R.string.dialog_positive_btn_ok), new DialogInterface.OnClickListener() {
            @Override
            public void onClick(DialogInterface dialog, int which) {
                String groupName = editText.getText().toString().trim();
                    ArrayList<MemberModel> memberList = getGroupMemberList();
                    if (!TextUtils.isEmpty(groupName)) {
                        if (groupName.matches(Utils.GROUP_NAME_REGEX)) {
                            createGroup(groupName, memberList);
                        } else {
                            editText.setError(getString(R.string.text_invalid_group_name));
                        }
                    } else {
                        Toast.makeText(context, getString(R.string.toast_group_name_empty), Toast.LENGTH_SHORT).show();
                    }
            }
        });
        builder.setNegativeButton(getString(R.string.dialog_negative_btn_cancel), new DialogInterface.OnClickListener() {
            @Override
            public void onClick(DialogInterface dialog, int which) {}});
        AlertDialog alert = builder.create();
        alert.show();
        Button negativeButton = alert.getButton(DialogInterface.BUTTON_NEGATIVE);
        negativeButton.setTextColor(ContextCompat.getColor(this, R.color.dialog_new_group_positive_button));
        Button positiveButton = alert.getButton(DialogInterface.BUTTON_POSITIVE);
        positiveButton.setTextColor(ContextCompat.getColor(this, R.color.dialog_new_group_positive_button));