Maps in Dart

main.dart

void main() {
  var nMap = <String, String>{
//key  //value
    '🎯': '#dart',
    '🏹': 'bow',
    '🧵': 'thread'
  };
  nMap['♥️'] = "#flutter";
  print(nMap['♥️']);

  // List of keys
  var keys = nMap.keys.toList();
  print(keys); // [🎯, 🏹, 🧵, ♥️]

// List of values
  print(nMap.values.toList()); //[#dart, bow, thread, #flutter]

  nMap.remove('🧵'); // put the key
  print(nMap); //{🎯: #dart, 🏹: bow, ♥️: #flutter}

  //Remove all values that do not divide by 2 without a remainder
  var newMap = <String, int>{'one': 1, 'two': 2, 'four': 4, 'seven': 7};
  newMap.removeWhere((key, value) => (value % 2 != 0));
  print(newMap); // {two: 2, four: 4}

  print(newMap.isEmpty); // false
  print(newMap.isNotEmpty); // true

  // first Map entry
  print(newMap.entries.first); //MapEntry(two: 2)
  print(newMap.entries.last); //MapEntry(four: 4)

  var containsKey = nMap.containsKey('🎯');
  print(containsKey); //true
  print(nMap.containsValue('#flutter')); //true

  // Looping over elements of a map
  //For
  for (var item in nMap.entries) {
    //You can use nMap.keys or nMap.values
    print('Key: ${item.key} and Value: ${item.value}');
  }
//forEach
  nMap.forEach((key, value) => print('$key : $value'));
}