Check out example codes for "pass by reference in dart". It will help you in understanding the concepts better.

Code Example 1

//Dart doesn't support pass by reference. You could try wrapping it in a class

class PrimitiveWrapper {
  var value;
  PrimitiveWrapper(this.value);
}

void alter(PrimitiveWrapper data) {
  data.value++;
}

main() {
  var data = new PrimitiveWrapper(5);
  print(data.value); // 5
  alter(data);
  print(data.value); // 6
}

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