How to translate String in ordinary class without return Scaffold?

[rrifafauzikomara]

I have the class for validation like here:

class Validator {

  String validateEmail(String value) {
    Pattern pattern =
        r'^(([^<>()[\]\\.,;:\s@\"]+(\.[^<>()[\]\\.,;:\s@\"]+)*)|(\".+\"))@((\[[0-9]{1,3}\.[0-9]{1,3}\.[0-9]{1,3}\.[0-9]{1,3}\])|(([a-zA-Z\-0-9]+\.)+[a-zA-Z]{2,}))$';
    RegExp regex = new RegExp(pattern);
    if (value.length == 0 ) {
      return "Email tidak boleh kosong";
    } else if (!regex.hasMatch(value)) {
      return 'Email tidak valid';
    }
    return null;
  }

  String validatePassword(String value) {
    String pattern = r'(^[a-zA-Z0-9]*$)';
    RegExp regExp = new RegExp(pattern);
    if (value.length == 0) {
      return "Password tidak boleh kosong";
    } else if(value.length < 8){
      return "Password tidak boleh kurang dari 8";
    } else if(value.length > 15) {
      return "Password tidak boleh lebih dari 15";
    } else if (!regExp.hasMatch(value)) {
      return "Password harus menggunakan alfanumerik";
    }
    return null;
  }
}

How to translate the value of return String?

[rrifafauzikomara]

I already ask StackOverflow too

[fajarainul]

@rrifafauzikomara how you solve this issue??