How to convert String List to String in flutter?

 print(list.toString().replaceAll('[', '').replaceAll(']',''))

if you know you have List<String> then you can use join() function provided by a flutter.

    var list = ['one', 'two', 'three'];
    var stringList = list.join("");
    print(stringList); //Prints "onetwothree"

Simple and short. ;)

And you can use it like this:

 List<String> servicesList = ["one", "Two", "Thee"]; 
 print(servicesList.join(""));

You can iterate list and concatenate values with StringBuffer

  var list = ['one', 'two', 'three'];
  var concatenate = StringBuffer();

  list.forEach((item){
    concatenate.write(item);
  });

  print(concatenate); // displays 'onetwothree'

  }

You can use reduce method on a list like that:

List<String> list = ['one', 'two', 'three'];
final string = list.reduce((value, element) => value + ',' + element);

// For your example:
List<String> servicesList = await SharedPrefSignUp.getSelectedServices();
selectServicesText = servicesList.reduce((value, element) => value + ',' + element);