How to add a character in EditText after user starts typing

Question

I have an editText where a user inputs a phone number, but right when they click their first number, I want a \'+\' to appear in the beginning of the text. I have this code but

Answer 1

    if (s.length == 1){ 
          if (s.toString().equals("+"))  editText.setText""
          else editText.setText("+"+s.toString)
          }