join method Null safety

String join(
  1. [String separator = ""]
)
override

Converts each element to a String and concatenates the strings.

Iterates through elements of this iterable, converts each one to a String by calling Object.toString, and then concatenates the strings, with the separator string interleaved between the elements.

Example:

final planetsByMass = <double, String>{0.06: 'Mercury', 0.81: 'Venus',
  0.11: 'Mars'};
final joinedNames = planetsByMass.values.join('-'); // Mercury-Venus-Mars

Implementation

String join([String separator = ""]) {
  Iterator<E> iterator = this.iterator;
  if (!iterator.moveNext()) return "";
  StringBuffer buffer = StringBuffer();
  if (separator == null || separator == "") {
    do {
      buffer.write("${iterator.current}");
    } while (iterator.moveNext());
  } else {
    buffer.write("${iterator.current}");
    while (iterator.moveNext()) {
      buffer.write(separator);
      buffer.write("${iterator.current}");
    }
  }
  return buffer.toString();
}