Android align message to center in alertDialog

AlertDialog.Builder alert = new AlertDialog.Builder(this);
alert.setTitle("It is title");
alert.setMessage("hey");
alert.setPositiveButton("Ok", null);
     
AlertDialog dialog = alert.show();
TextView tv_message = (TextView)dialog.findViewById(android.R.id.message);
tv_message.setGravity(Gravity.CENTER);
dialog.show();