dart_list_set_map.dart

dart_list_set_map.dart

void main() {
  
  
  // List
  List<int> list1 = [1, 2, 3]; // List<int>
  List<int> list3 = []; // Empty list
  List<String> list2 = ['', 'sdf', ''];
  int item0List1 = list1[0]; // read value
  list1[0] = 5; // set value for index = 0
  list3 = [
    // copy list with (...)
    ...list1,
    4
  ];
  List<int> list4 = list1.map((int e) => e + 1).toList();
  List<String> list1CastToStr =
      list1.map((int e) => e.toString()).toList().cast<String>();
  print(list1CastToStr);

  
  // Sets
  Set<String> halogens = {'add', 'chlorine', 'brom'};
  print('set length ${halogens.length}');
  halogens.add('add'); // add value
  print('set length ${halogens.length}');
  bool isContainAdd = halogens.contains('add');

  
  // Map
  var gifts = {
    // Key:    Value
    'first': 'partridge',
    'second': 'turtledoves',
    'fifth': 'golden rings'
  }; // Map<String, String>
  var firstGifts = gifts['first']; // read value by key
  gifts['second'] = 'robot'; // set value by key

  
  // List, Sets and Map have simular functionality: length, forEach, map, for ... in

  // Use is and collection if.
  final listValue = 2;
  final aList = [
    1,
    2,
    3,
    4,
    if (listValue > 0) listValue
  ]; // Use is and collection if.
  final bList = [
    10,
    30,
    ...aList,
  ]; // spread.
}