mapswap.dart

void main() {

Map<dynamic, dynamic> moneyOut = {
  'App' : 70,
  'Flutter' : 400,
  'Issam Alameh': 260,
  'Life Arms': 1100,
  'Success': 30,
  'Legend': 80,
  'Smart Work': 850,
  'this app is powerful': 2800,
  };
  
    
  var list = moneyOut.keys.toList();
  list.swap(3,2);
  print(moneyOut);
  


  moneyOut = moneyOut.swap(3,2);
  print(moneyOut);
  
   moneyOut = moneyOut.swap(7,-4);
  print(moneyOut);
  }
extension ListUtils<T> on List<T> {
  num sumBy(num f(T element)) {
    num sum = 0;
    for (var item in this) {
      sum += f(item);
    }
    return sum;
  }

  swap(int oldIndex, int newIndex) {
    if (newIndex >= this.length) newIndex = this.length - 1;
    if (newIndex < 0) newIndex = 0;
    var tmp = this[oldIndex];
    this[oldIndex] = this[newIndex];
    this[newIndex] = tmp;
  }
}

extension MapUtils on Map {
  swap(oldIndex, newIndex) {
    print('$oldIndex, $newIndex');
    var tmpKeys = List.of(this.keys.toList());
    var tmpValues = List.of(this.values.toList());
    tmpKeys.swap(oldIndex, newIndex);
    tmpValues.swap(oldIndex, newIndex);

    return {
      for (int index = 0; index < tmpKeys.length; index++)
        tmpKeys[index]: tmpValues[index]
    };
  }
}